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Lbrasci
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Reged: 12/20/12

Loc: South Florida
Nexstar 8 Original Silver Align/ GPS Problem
      #5654695 - 01/31/13 05:03 PM

My first post and first goto telescope.

I recently bought a used celestron nexstar 8 original silver and I am having hard time aligning by auto-align and 2 star align. On the the auto-align option I have North/level and entered the correct time, date, lattitude, longitude, etc so then the telescope automatically slews to sirius but it slews to another location not sirius, I have tried different stars but same result. Also with the 2 star alignment I make sure I am using the correct starts (I double checked with google night sky app)I picked sirius and capella but the telescope says "bad alignment" I have tried different stars but same result. Please help as I have watched and read about 5-6 hours worth of online literature with no success. One last thing when I go to menu and go to the azm /alt option and I am pointing telescope North and parrallel to ground it reads azm 193 degrees and alt -59 degrees. Shouldnt it be approximatelly 0 degrees and 0 degrees? I tried to trick the computer and used the 193/-59 degree location as my North and level but it did not work either. Thank you in advance as this has been driving me crazy,


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Arthur Dent
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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5654705 - 01/31/13 05:08 PM

Whoa!

3 duplicate posts.

Need to delete 2 of 'em!

Can't help with original NexStar8i though.

Art


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BigC
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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5655159 - 01/31/13 09:59 PM

Check the handset for stored location.It might be defaulting to a previous owner's locatiion and thus skewing the results by a timezone. Is the result consistent and about how far off from the desired star?
I bought a used 8Se from a person who wasn't happy with it-said it never quite put the target into the eyepiece.Turned out he had never known changed the observing location stored in the handset,and the previous owner was several hundred miles and a timezone away.

If you don't have the manual try to download it from Celestron .


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WaterMasterAdministrator
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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: BigC]
      #5655388 - 02/01/13 12:24 AM

I had another thought - I once spent an agonizing night of alignment failures before I realized I had not changed the Daylight Savings Time setting.

Also, I would think your encoders should read 0 and 90 when pointed due north and level, but I've never used that function. At first I thought maybe the OTA had been mounted backwards, which would give you 180 and -90 (or maybe 270), which isn't that far off what you're seeing, but I would think if the OTA were mounted 'backwards' it would be obvious.

Finally, check to make sure you have the correct hemisphere (your latitude entry needs to be North).


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Lbrasci
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Reged: 12/20/12

Loc: South Florida
Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: BigC]
      #5655532 - 02/01/13 03:25 AM

Quote:

Check the handset for stored location.It might be defaulting to a previous owner's locatiion and thus skewing the results by a timezone. Is the result consistent and about how far off from the desired star?
I bought a used 8Se from a person who wasn't happy with it-said it never quite put the target into the eyepiece.Turned out he had never known changed the observing location stored in the handset,and the previous owner was several hundred miles and a timezone away.

If you don't have the manual try to download it from Celestron .




No information is saved once turned off. I downloaded the manual and it was no help. I would say final result is pretty consistence. Thanks for your input.


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Lbrasci
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Reged: 12/20/12

Loc: South Florida
Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: WaterMaster]
      #5655539 - 02/01/13 03:38 AM

Quote:

I had another thought - I once spent an agonizing night of alignment failures before I realized I had not changed the Daylight Savings Time setting.

Also, I would think your encoders should read 0 and 90 when pointed due north and level, but I've never used that function. At first I thought maybe the OTA had been mounted backwards, which would give you 180 and -90 (or maybe 270), which isn't that far off what you're seeing, but I would think if the OTA were mounted 'backwards' it would be obvious.

Finally, check to make sure you have the correct hemisphere (your latitude entry needs to be North).




I tried both daylight savings and standard time. My latitude is +26 degrees and longitude is W 80 degrees so what would be my encoders read if my telescope is pointed North and level? Is it azm 0 degrees and alt 90 degrees or azm 0 degrees and alt 64 degrees (90-26 my latitude)? Thanks.

Edited by Lbrasci (02/01/13 03:48 AM)


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Lbrasci
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Reged: 12/20/12

Loc: South Florida
Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5655548 - 02/01/13 03:47 AM

One more issue, its about 3:44am in Florida and I was trying to align and it freezes everytime I select AM for the time.

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Tel
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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5655608 - 02/01/13 05:37 AM

Hi Lbrasci,

Welcome to CN and to this forum !

There seems to be a number of factors coming together here to complicate the single objective of getting your Nexstar 8 (Original) to align and work, so let's try to dispense with some I would class as irrelevant at this stage.

In the first instance, forget about the "Get Alt/Az. Axis".

I have a Nexstar 8i mount which is very similar to yours and, in aligning my index marks on the 'scope and mount arm respectively to place the tube horizontally, my Alt. reading is ca. minus 53 degrees (cf. your minus 59 degrees) and the Az. figure can be anything subject to revoving the mount in azimuth ! I hasten to add I don't know why but nether do I care. I have never had cause to use this function.

So to the more relevant:

Assuming that you are indeed entering your correct (standard) time and date and have installed the appropriate, Time Zone (EST) plus you Latitude and Longitude and that you choose, (say), "Auto Align", you appear to refer to the fact that having chosen Sirius followed by Capella, the scope slews, (to one after the other), in their respective directions but misses both. (?)

If this is true; now comes the dumb question: if in slewing the 'scope misses, (by say, not more than a degree or two), the first alignment star, (Sirius), are you actually manipulating the hand control direction buttons to bring it into view in your eyepiece ?

If not and you are merely entering it as an "Align" then you will never get a successful alignment. (Similarly with the second alignment star, Capella).

I repeat, I know the question is a dumb one and if you are centralising your alignment stars in your eyepiece then please forgive me for asking, but with problems like this every piece of information gained helps to solve the puzzle.

However, in referring to the above, what complicates this issue (for me), is that you mentioned you had also used the "manually" applied "Two Star Align", in which case you would have had to manually slewed the 'scope in turn to both alignment stars and centralised both in your eyepiece. Is this not true and this is in fact what you did when applying this alternative alignment method ?

Stick with it: I'm sure we can come up with an answer !

Best regards,
Tel
Edit: BTW. I don't have any answers at the moment regarding the "AM" time issue, but this can be easily check tested as to whether the problem DOES indeed exist by merely entering any time value between say, 12:01 and 11:59 and applying an AM value to it.

If the hand controller just won't accept an AM value, then obviously therein lies "the" or an additional problem to consider.

Edited by Tel (02/01/13 05:47 AM)


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Bob Griffiths
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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5656347 - 02/01/13 01:17 PM

...DO YOU IN FACT have a GPS unit hooked up to the scope...???

1 If so what does it indicate you position as..and what time is it showing..???

Now have you calibrated the GPS unit? (I'm assuming its a Celestron CN-16) for both NORTH and for LEVEL... I'm guessing not because you have to actually get it aligned before you can do that.. and you have not...

BUT the previous owner may have calibrated it and now the scope may actually be altering or over or under compensating trying to actually find North and level.. Just food for though... and I'd like to know if you hear a rattle in the GPS unit if you tilt it back and forth ..you should as a simple ball bearing rolls around and that ball bearing has been know to get stuck...

I always run my scope on Standard time year round
and in the summer I just make sure the scope (the time the GPS displays) is 10 PM instead of 9 PM like my watch tells me ...

I sure would not expect the scope to slew directly to either of your first 2 alignment stars.. It usually is way off on the first and completely out in left field on the second...Because its still guessing where the heck it is

One more question...are you sure its a plain 8 with one port in the base or is it an 8i with 2 ports ts in the base... Several of us still run 8i's but I do not know of anyone still running a original 8

Bob G.


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Lbrasci
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Reged: 12/20/12

Loc: South Florida
Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5656479 - 02/01/13 02:32 PM

Quote:

Hi Lbrasci,

Welcome to CN and to this forum !

There seems to be a number of factors coming together here to complicate the single objective of getting your Nexstar 8 (Original) to align and work, so let's try to dispense with some I would class as irrelevant at this stage.

In the first instance, forget about the "Get Alt/Az. Axis".

I have a Nexstar 8i mount which is very similar to yours and, in aligning my index marks on the 'scope and mount arm respectively to place the tube horizontally, my Alt. reading is ca. minus 53 degrees (cf. your minus 59 degrees) and the Az. figure can be anything subject to revoving the mount in azimuth ! I hasten to add I don't know why but nether do I care. I have never had cause to use this function.

So to the more relevant:

Assuming that you are indeed entering your correct (standard) time and date and have installed the appropriate, Time Zone (EST) plus you Latitude and Longitude and that you choose, (say), "Auto Align", you appear to refer to the fact that having chosen Sirius followed by Capella, the scope slews, (to one after the other), in their respective directions but misses both. (?)

If this is true; now comes the dumb question: if in slewing the 'scope misses, (by say, not more than a degree or two), the first alignment star, (Sirius), are you actually manipulating the hand control direction buttons to bring it into view in your eyepiece ?

If not and you are merely entering it as an "Align" then you will never get a successful alignment. (Similarly with the second alignment star, Capella).

I repeat, I know the question is a dumb one and if you are centralising your alignment stars in your eyepiece then please forgive me for asking, but with problems like this every piece of information gained helps to solve the puzzle.

However, in referring to the above, what complicates this issue (for me), is that you mentioned you had also used the "manually" applied "Two Star Align", in which case you would have had to manually slewed the 'scope in turn to both alignment stars and centralised both in your eyepiece. Is this not true and this is in fact what you did when applying this alternative alignment method ?

Stick with it: I'm sure we can come up with an answer !

Best regards,
Tel
Edit: BTW. I don't have any answers at the moment regarding the "AM" time issue, but this can be easily check tested as to whether the problem DOES indeed exist by merely entering any time value between say, 12:01 and 11:59 and applying an AM value to it.

If the hand controller just won't accept an AM value, then obviously therein lies "the" or an additional problem to consider.




Hi Tel,

When the telescope slews over to any of the stars (Sirius, capella, vega, etc) it misses by more than 90 degrees. After it misses by more than 90 degrees I have manually centralizing the stars within the eyepiece and then pressed align and repeated process for second star but it says bad alignment.

"However, in referring to the above, what complicates this issue (for me), is that you mentioned you had also used the "manually" applied "Two Star Align", in which case you would have had to manually slewed the 'scope in turn to both alignment stars and centralised both in your eyepiece. Is this not true and this is in fact what you did when applying this alternative alignment method ? "

Im not sure what you are trying to say here. But when i did the the 2 star align i would pick Sirius and then manually slew to sirius centralizing it on my eyepiece and then repeat process for second star but hand controller says bad alignment.

Thanks for your input and encouragement.


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Lbrasci
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Reged: 12/20/12

Loc: South Florida
Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Bob Griffiths]
      #5656506 - 02/01/13 02:49 PM Attachment (10 downloads)

Quote:

...DO YOU IN FACT have a GPS unit hooked up to the scope...???

1 If so what does it indicate you position as..and what time is it showing..???

Now have you calibrated the GPS unit? (I'm assuming its a Celestron CN-16) for both NORTH and for LEVEL... I'm guessing not because you have to actually get it aligned before you can do that.. and you have not...

BUT the previous owner may have calibrated it and now the scope may actually be altering or over or under compensating trying to actually find North and level.. Just food for though... and I'd like to know if you hear a rattle in the GPS unit if you tilt it back and forth ..you should as a simple ball bearing rolls around and that ball bearing has been know to get stuck...

I always run my scope on Standard time year round
and in the summer I just make sure the scope (the time the GPS displays) is 10 PM instead of 9 PM like my watch tells me ...

I sure would not expect the scope to slew directly to either of your first 2 alignment stars.. It usually is way off on the first and completely out in left field on the second...Because its still guessing where the heck it is

One more question...are you sure its a plain 8 with one port in the base or is it an 8i with 2 ports ts in the base... Several of us still run 8i's but I do not know of anyone still running a original 8

Bob G.




Hi Bob,

How do I verify if the GPS is hooked up? Maybe GPS needs calibration. It doesnt indicate position or time no information is saved once unit is turned off, I have to manually enter all info. The telescope does not automatically go to North and level I have to manually slew it over as per instruction on hand controller. I see one port (looks like telephone jack) on the backside of the hand controller. I am not sure if its the 8i or 8 I took a picture of it. Thanks.


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Tel
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Reged: 03/31/06

Loc: Wallingford England
Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5656667 - 02/01/13 04:15 PM

Hi Lbrasci,

No answers yet as such, but to clarify:

1) If your mount has no plug-in ports on the top of its battery box, then it will be a Celestron 8. If there are two ports on the battery box, (one labellled "Aux" the other, "Auto Guide"), then it will be a Celestron 8i.

2) "Two star Align", as opposed to "Auto Align".

Yes, what I meant was that with an N8/N8i "Auto Align", the 'scope makes both slews to the chosen alignment stars so obviously there is room for error as Bob indicated. In other words, it would be a sound bet that the slews might well miss their target star, (but not by much), demanding further manual slewing action on your part to bring said star into the centre of the eyepiece.

However noting that you have also carried out a "Two Star Align", you would have had to have moved the 'scope yourself, (via the hand controller's direction buttons), to each alignment star in turn. All this therefore and the fact that your 'scope under an "Auto Align" is ending its slews adrift by ca. 90 degrees, tells me that something is more seriously amiss here than mere pointing and eyepiece centralisation errors.

So where next:

Well, at this stage I would recommend that you abort any attempts to incorporate the use of the GPS if you have not already done so, as this only introduces another unwanted variable to complicate the problem.

Secondly, and a question I should have perhaps asked at the onset: what sort of power source are you using ?

Best regards,
Tel

Edited by Tel (02/01/13 04:20 PM)


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Lbrasci
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Reged: 12/20/12

Loc: South Florida
Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5656720 - 02/01/13 04:41 PM Attachment (11 downloads)

Quote:

Hi Lbrasci,

No answers yet as such, but to clarify:

1) If your mount has no plug-in ports on the top of its battery box, then it will be a Celestron 8. If there are two ports on the battery box, (one labellled "Aux" the other, "Auto Guide"), then it will be a Celestron 8i.

2) "Two star Align", as opposed to "Auto Align".

Yes, what I meant was that with an N8/N8i "Auto Align", the 'scope makes both slews to the chosen alignment stars so obviously there is room for error as Bob indicated. In other words, it would be a sound bet that the slews might well miss their target star, (but not by much), demanding further manual slewing action on your part to bring said star into the centre of the eyepiece.

However noting that you have also carried out a "Two Star Align", you would have had to have moved the 'scope yourself, (via the hand controller's direction buttons), to each alignment star in turn. All this therefore and the fact that your 'scope under an "Auto Align" is ending its slews adrift by ca. 90 degrees, tells me that something is more seriously amiss here than mere pointing and eyepiece centralisation errors.

So where next:

Well, at this stage I would recommend that you abort any attempts to incorporate the use of the GPS if you have not already done so, as this only introduces another unwanted variable to complicate the problem.

Secondly, and a question I should have perhaps asked at the onset: what sort of power source are you using ?

Best regards,
Tel




Hi Tel,

Below the mount arm and on the side of the battery box there is a port for a in wall electrical plug (please see attached picture), there are no plug ports on top of the battery box.

I am connecting it to my electrical wall outlet using 120w. Should I try using batteries?

Thanks.


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Tel
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Reged: 03/31/06

Loc: Wallingford England
Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5656830 - 02/01/13 05:36 PM

Hi Lbrasci,

Yes, that's the external power supply's receiving socket and I now see, from your earlier image, the cord feeding it from your mains wall socket; presumably via a suitable transformer.

Now, with the use of a transformer supply, there are a number of aspects to consider.


1) What is its rating ? (Input voltage/output voltage and max. current rating).

I also have to say that I wasn't sure what you meant by 120w ? Did you mean Watts or Volts or ...... ?

2) The cord connection, (jack plug), at the mount, should be of 5.5 mm outer diameter/2.1mm inner diameter. What you might find however, is that the jack plug's inner diameter is the more standard 2.5mm variety, which can lead, in this application, to possible intermittent electrical supply to the mount.

Does the connection feel at all loose particularly at the mount ?

3) You say you use mains supply from your wall socket as demonstrated by your first posted photo. However, is there enough wire there for when you take your 'scope outdoors ? In other words, how you are operating this 'scope outdoors in terms of power supply, is not clear.

Can you help us out on a fuller explanation ? An extension cord perhaps ?

4) Finally, yes, try some FRESH AA batteries in the mount rather than the power source you are using and check the effect. They will only give you something like a couple of hours' use but that will suffice to determine and compare the mount's electrical supply acceptance.

Do NOT though, connect both external supply in the presence of the batteries at this stage because as soon as the external supply is connected, the batteries go into a dormant state. Primarily, we need to isolate the internal battery power source from the external for the purpose of power source comparison.

Hoping this may reveal a little more as to the reasons for this odd behaviour.

Best regards,
Tel

BTW. That IS a Nexstar 8 you have there !

Edited by Tel (02/01/13 06:13 PM)


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Lbrasci
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Reged: 12/20/12

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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5657557 - 02/02/13 03:41 AM

Quote:

Hi Lbrasci,


Yes, that's the external power supply's receiving socket and I now see, from your earlier image, the cord feeding it from your mains wall socket; presumably via a suitable transformer.

Now, with the use of a transformer supply, there are a number of aspects to consider.


1) What is its rating ? (Input voltage/output voltage and max. current rating).

I also have to say that I wasn't sure what you meant by 120w ? Did you mean Watts or Volts or ...... ?

2) The cord connection, (jack plug), at the mount, should be of 5.5 mm outer diameter/2.1mm inner diameter. What you might find however, is that the jack plug's inner diameter is the more standard 2.5mm variety, which can lead, in this application, to possible intermittent electrical supply to the mount.

Does the connection feel at all loose particularly at the mount ?

3) You say you use mains supply from your wall socket as demonstrated by your first posted photo. However, is there enough wire there for when you take your 'scope outdoors ? In other words, how you are operating this 'scope outdoors in terms of power supply, is not clear.

Can you help us out on a fuller explanation ? An extension cord perhaps ?

4) Finally, yes, try some FRESH AA batteries in the mount rather than the power source you are using and check the effect. They will only give you something like a couple of hours' use but that will suffice to determine and compare the mount's electrical supply acceptance.

Do NOT though, connect both external supply in the presence of the batteries at this stage because as soon as the external supply is connected, the batteries go into a dormant state. Primarily, we need to isolate the internal battery power source from the external for the purpose of power source comparison.

Hoping this may reveal a little more as to the reasons for this odd behaviour.

Best regards,
Tel

BTW. That IS a Nexstar 8 you have there !




Hi Tel,

1. Transformer supply input 100-240v 50/60hz 0.8A and output 12v 2.0A. Yea electricity supplied fom outlets is 120 volts.

2. Yes the connection does feel a little loose at the mount. I wonder if I am using the wrong transformer supply which is causing the problems.

3. I connect to outside/exterior outlets so there is always enough wire. No extension cord used.

4. Ill buy some batteries and test.

Thanks for your help and patience.


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Tel
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Reged: 03/31/06

Loc: Wallingford England
Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5657591 - 02/02/13 05:10 AM

Hi Lbrasci,

No trouble at all ! I just hope we can crack this one !

One or two thoughts overnight:

If you basically "kid" your 'scope into thinking you're setting it up for an observing session, i.e. by entering, say, 10:00pm (or 22:00h), and today's date, you can of course experiment with the problem at any time today and thus not have to wait until any "real" stars appear !

All you have to know is the rough positions of your chosen alignment stars, (in your choice Sirius and Capella), and make a mock alignment in the comfort of your living room as they say !

According to my estimation, Sirius will be almost due South from Florida at ca. 10:00pm (22:00h) while Capella will be due North so that in making your mock, (daytime), alignment, with its entered, false time, your 'scope should slew in turn, to these directions.

If however, the 'scope slews as you stated, some 90 degrees away from either of these positions using either mains or AA battery power, then this two stage experiment shows that it's unlikely that the problem is power supply related.

In carrying out this experiment, make sure your transformer cord is a tight fit at both ends. This you can effect at the mount, by CAREFULLY spreading the two halves of the receiving pin to gain a tighter cord fit.

Your transformer's specification is OK. Just make sure the cord connections are sound at both ends as described and, if you can, check the continuity of the cord wire itself.

Once we've established that the 'scope is slewing roughly to where it should and not some 90 degrees "off" each time then we can begin to accurise its performance.

One question though: the "90 degrees off" you recorded; is this consistent or can this "angle of miss" be random ?

Interested to learn how you get on,

Best regards,
Tel


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Tel
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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5657618 - 02/02/13 06:21 AM

A couple of afterthoughts :

1) Don't buy re-chargeable AA batteries.

Most only give a nominal 1.2 Volts leading to only a total of 8X1.5 = 9.6 Volts instead of 12 Volts to power the 'scope. This is insufficient, at least for the purpose of this expeiment, when a full 12V is required.

2) The Nexstar 8 is particularly sensitive to pre-alignment. Level the tripod with a bubble level and, after attaching the mount and tube, also level the tube in its pre-alignment horizontal position on the mount.

3) Point as near to due North as you are able. (Compass)?

This should help a little further to iron out some more of the variables.

Best regards,
Tel


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Midnight Dan
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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5657829 - 02/02/13 10:05 AM

Hi Lbrasci:

I'm coming in a little late to this party, but it looks like you're getting the usual excellent help from Tel and others. Just wanted to add a couple of thoughts.

When you set the scope to north and level, do you do so BEFORE turning the power on? When powered on, the scope assumes that the current position is north and level so you have to do that first. If you use the handset to slew it to a north/level position before alignment, then be sure to power it off then on again so it resets the software to the new position as north/level.

Also, I believe Tel suggested you abandon the use of the GPS at this point. Have you tried it again with the GPS disconnected?

-Dan


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Tel
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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Midnight Dan]
      #5657926 - 02/02/13 11:11 AM

Hi Dan,

It is possible that this power "switch off" is a necessity when North aligning the Nexstar 8 and certainly can do no harm to perform, but having bought its successor, the Nexstar 8i, back in '06, this step was not required.

Indeed, such was the case with the N8i, that the "Auto Align" procedure required one to switch on, enter time, date and confirm HC retained data, and then, to a further HC prompt, "Move the optical tube to its North and Index position".

Once this "Move" was established and "Entered", the HC would merely proceed to the next stage of the alignment operation. (Note however that there are no index marks on the original N8, so accurate bubble levelling is advisable. Index marking can of course be made/added on a DIY basis at any time).

Incidentally, the method I used to use to ensure I had a good "North Alignment", was to place Polaris in my EP before starting any alignment procedure and then, by means of the "down" button on the HC, bring the OTA back down to align the index marks without moving the mount at all in azimuth.

In Lb's case here, however, this may not be so easy or even an option at Polaris' altitude of ca. 26 degrees in Southern Florida, compared to my UK ca. 52 degrees !

On the other hand, if he does have free access to Polaris with his 'scope, I believe it's a good method for achieving an accurate, initially required "North" alignment.

Best regards,
Tel

Edited by Tel (02/02/13 11:17 AM)


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Midnight Dan
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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5657958 - 02/02/13 11:29 AM

Hi Tel:

Quote:

Indeed, such was the case with the N8i, that the "Auto Align" procedure required one to switch on, enter time, date and confirm HC retained data, and then, to a further HC prompt, "Move the optical tube to its North and Index position".




Interesting! I owned an original 8 a few years ago when I first got into the hobby. I don't remember that step in the alignment procedure. Perhaps the 8 procedure is different because it doesn't have the index marks?

Of course, my memory isn't that great and it was a few years ago, so I certainly could be mis-remembering!



-Dan


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Midnight Dan]
      #5658007 - 02/02/13 12:01 PM

H Dan,

Please accept that I may well also be wrong when it comes to aligning an N8 as opposed to an N8i and "switching off" was/is indeed necessary. It's as I said: I just don't know with any certainty.

Best regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5658295 - 02/02/13 02:54 PM

Quote:

H Dan,

Please accept that I may well also be wrong when it comes to aligning an N8 as opposed to an N8i and "switching off" was/is indeed necessary. It's as I said: I just don't know with any certainty.

Best regards,
Tel




Tel:

I recently acquired an original Nexstar 5 which I believe uses the exact same mount as the Nexstar 8. I am not quite sure how the GPS is hooked up? I did not think there was an option for that.

In any event, this is what I have done:

I use a digital level to level the base and then point the scope north and level the scope itself. I have not switched off the scope after pointing it north. After that I enter the longitude and latitude, the time zone, the time. I select auto align and it points reasonably close to Sirius, I align it, it points reasonably close to Capella, I align it and it's done. After that it puts objects within the field of view of a 32mm Plossl.

According to what I am reading, this Nexstar 8 is off by 90 degrees or more. To miss that badly, I can only think that somehow the latitude or longitude have the wrong sign or that the time is being entered as a 12 hour number (7:00) rather than a 24 hour number (19:00).

Jon


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5658343 - 02/02/13 03:20 PM

Quote:

Hi Lbrasci,

No trouble at all ! I just hope we can crack this one !

One or two thoughts overnight:

If you basically "kid" your 'scope into thinking you're setting it up for an observing session, i.e. by entering, say, 10:00pm (or 22:00h), and today's date, you can of course experiment with the problem at any time today and thus not have to wait until any "real" stars appear !

All you have to know is the rough positions of your chosen alignment stars, (in your choice Sirius and Capella), and make a mock alignment in the comfort of your living room as they say !

According to my estimation, Sirius will be almost due South from Florida at ca. 10:00pm (22:00h) while Capella will be due North so that in making your mock, (daytime), alignment, with its entered, false time, your 'scope should slew in turn, to these directions.

If however, the 'scope slews as you stated, some 90 degrees away from either of these positions using either mains or AA battery power, then this two stage experiment shows that it's unlikely that the problem is power supply related.

In carrying out this experiment, make sure your transformer cord is a tight fit at both ends. This you can effect at the mount, by CAREFULLY spreading the two halves of the receiving pin to gain a tighter cord fit.

Your transformer's specification is OK. Just make sure the cord connections are sound at both ends as described and, if you can, check the continuity of the cord wire itself.

Once we've established that the 'scope is slewing roughly to where it should and not some 90 degrees "off" each time then we can begin to accurise its performance.

One question though: the "90 degrees off" you recorded; is this consistent or can this "angle of miss" be random ?

Interested to learn how you get on,

Best regards,
Tel




Hi Tel,

I have tried experimenting during the daytime for different stars as I know the location of a star by using google sky app. The 90 degree off is pretty consistent even with other stars i.e. sirius, capella, vega, etc. Thanks.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Midnight Dan]
      #5658363 - 02/02/13 03:31 PM

Hi Dan,

I have previously tried both:

I have power on and then slewed over to north and level. I also have tried north/level and then turned power off so when i turn on its already north/level. Both methods did not work.

How is GPS turned off/ disconnected? Thanks.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5658370 - 02/02/13 03:36 PM

Quote:

A couple of afterthoughts :

1) Don't buy re-chargeable AA batteries.

Most only give a nominal 1.2 Volts leading to only a total of 8X1.5 = 9.6 Volts instead of 12 Volts to power the 'scope. This is insufficient, at least for the purpose of this expeiment, when a full 12V is required.

2) The Nexstar 8 is particularly sensitive to pre-alignment. Level the tripod with a bubble level and, after attaching the mount and tube, also level the tube in its pre-alignment horizontal position on the mount.

3) Point as near to due North as you are able. (Compass)?

This should help a little further to iron out some more of the variables.

Best regards,
Tel




Hi Tel,

I'll try item #2 (taking it apart/ leveling )and I use an phone app as a compass. Thanks.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5658383 - 02/02/13 03:43 PM

Hi Lbrasci,

With that 90 degree consistency and presumably a now confirmed reliable power source, I would certainly go along with Jon's suggestions in as much as something in your basic entered data is screwing up the ability of this 'scope to align accurately.

Can you therefore make a double check along the lines he's mentioned: i.e. ensure that your time is either in military format or according to an appropriate am/pm : that the date is in accordance with American format: (mm/dd/yyyy) your Time Zone is set to EST : and that your lat./long. are correct and not transposed.

Can you please confirm ?

Best regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Jon Isaacs]
      #5658407 - 02/02/13 03:55 PM

Quote:

Quote:

H Dan,

Please accept that I may well also be wrong when it comes to aligning an N8 as opposed to an N8i and "switching off" was/is indeed necessary. It's as I said: I just don't know with any certainty.

Best regards,
Tel




Tel:

I recently acquired an original Nexstar 5 which I believe uses the exact same mount as the Nexstar 8. I am not quite sure how the GPS is hooked up? I did not think there was an option for that.

In any event, this is what I have done:

I use a digital level to level the base and then point the scope north and level the scope itself. I have not switched off the scope after pointing it north. After that I enter the longitude and latitude, the time zone, the time. I select auto align and it points reasonably close to Sirius, I align it, it points reasonably close to Capella, I align it and it's done. After that it puts objects within the field of view of a 32mm Plossl.

According to what I am reading, this Nexstar 8 is off by 90 degrees or more. To miss that badly, I can only think that somehow the latitude or longitude have the wrong sign or that the time is being entered as a 12 hour number (7:00) rather than a 24 hour number (19:00).


Jon




Hi Jon,

I have checked my latitude and longitude here in Lighthouse Point, Florida (Latitude: 26-16 N
Longitude: 080-05 W) about 20 times and I am not exagerating and I have tried both 12hour and 24 hour formats. Maybe I need to try a digital level.

Thanks.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5658534 - 02/02/13 05:13 PM

Ok here is the latest.

I have made the following changes and have gotten same results:

1. Brand new batteries out of the box.
2. Tripod digitally leveled.
3. OTA digitally leveled.
4. Pointing true North used 2 different digital compass to verify.

Same results about 90 degrees off. The batteries and 120v electrical power took me to same location for sirius when I ran test. I guess brightside to all this is that its consistent with sirius location.

This is driving me nuts.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5658575 - 02/02/13 05:37 PM

Sorry, Lb, but the last comment is unclear to me.

Are you saying that when you carry out an "Auto Align" and choose Sirius as your first alignment star the 'scope does in fact reach Sirius' basic location but that the second alignment star is 90 degs. off as usual, OR, that even in making its slew to Sirius, this slew still ends up 90 degs. off ?

Best regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5658604 - 02/02/13 05:50 PM

Quote:

Sorry, Lb, but the last comment is unclear to me.

Are you saying that when you carry out an "Auto Align" and choose Sirius as your first alignment star the 'scope does in fact reach Sirius' basic location but that the second alignment star is 90 degs. off as usual, OR, that even in making its slew to Sirius, this slew still ends up 90 degs. off ?

Best regards,
Tel




Hi Tel,

When I ran alignment Sirius was 90 degrees off when i used either batteries or electrical power. Sorry for the confusion. Thanks.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5658634 - 02/02/13 06:04 PM

Additionally, does your hand controller version ask for a latitude co-ordinate followed by a choice between North or South and a longitude co-ordinate followed by a choice between East or West or, does it require you use a "plus/minus system.

Here I quote what Mike Swanson has to say on this subject from his book, "The Nexstar User's Guide".

Quote:

If your version of Nexstar asks for a + or - for latitude, + is north latitude.

Note that on the original Nexstar 5 and 8, storing your longitude and latitude in adjacent "stored locations" will corrupt the entries. This results in the Auto Alignment procedure missing the two alignment stars.

To prevent this problem, only store and use longitude and latitude in locations 0,4,8 or 1, 5, 9.

Does this information perhaps help ?

Incidentally, what HC version are you in fact using ?

Best regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5658801 - 02/02/13 07:47 PM

Quote:

Additionally, does your hand controller version ask for a latitude co-ordinate followed by a choice between North or South and a longitude co-ordinate followed by a choice between East or West or, does it require you use a "plus/minus system.

Here I quote what Mike Swanson has to say on this subject from his book, "The Nexstar User's Guide".

Quote:

If your version of Nexstar asks for a + or - for latitude, + is north latitude.

Note that on the original Nexstar 5 and 8, storing your longitude and latitude in adjacent "stored locations" will corrupt the entries. This results in the Auto Alignment procedure missing the two alignment stars.

To prevent this problem, only store and use longitude and latitude in locations 0,4,8 or 1, 5, 9.

Does this information perhaps help ?

Incidentally, what HC version are you in fact using ?

Best regards,
Tel




Hi Tel,

My controller gives me choice of W and E and + or - system. Yes I use + for my latitude. I have not stored any locations, I looked for stored location on the main menu but I couldnt find it. The only place it mentions stored location is when it asks if you want longitute and latitude saved. I guess what I can do is put my longitude and latitude on all 10 locations. Or maybe there is another way to reset to default settings or erase all? What is HC = hand controller? Incase hc is hand controller I checked it and there are no markings or wording to indicate model or version. I am assuming its the original the one with only 18000 objects. Thanks.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5658809 - 02/02/13 07:52 PM

Update:

I again tried the 2 star alignment but it didnt work still says "bad alignment" eventhough I used 5 different stars.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5658879 - 02/02/13 08:33 PM

Hi Lb,

Yes HC means hand controller.

Your HC version should be accessible via this part of Mike Swanson's Nexstar website.

http://www.nexstarsite.com/Firmware/N58Firmware.htm

As to permanent entry of your lat./long. co-ordinates, you will find how to do this on page 15 of your manual.

I understood that you had downloaded the manual but just in case, it may again be accessed via Mike's site according to:

http://www.nexstarsite.com/Manuals.htm

Just look down the page until you see the listing for the N8 manual and if necessary download it.

I hope this helps.

I must now away to my bed as it's 01:30 hours here in the UK !

Best of luck and regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5659336 - 02/03/13 03:44 AM

Hi Tel,

The HC version does not appear when I power on or when I press all 4 arrows when I power on as per recommended website.

Also, yeah I had previously read page 15 of the manual and it doesnt tell you how to delete.

Thanks and goodnight.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5659339 - 02/03/13 03:55 AM

Who can I take the scope to so that they can diagnose issue? I wonder if its a matter of GPS calibration, giving it some maintenance, or does the computer need to be completely replaced. I wonder how much it would cost to fix and is it worth fixing in lieu of buying a new one. I actually called the dude that advertises on this site that offers repair services but he has yet to call me back this was 3 days ago.

If I were to sell it in its present condition how much would it be worth? Optically and mechanically its perfect just the GPS and/ or computer issues. I guess if someone is looking for an 8" celestron nexstar and they dont need the computerized part it would be perfect for them.

Edited by Lbrasci (02/03/13 03:59 AM)


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5659353 - 02/03/13 04:26 AM

Hi Lb and good morning !

Some overnight thoughts.

1) Without attempting to make any alignment at all, have you checked that both axes rotate freely in as much as the altitude axis can be powered via the HC, from a point where the 'scope tube, (OTA), is almost resting on the base of the mount to the vertical and back again without any signs of slippage, or other recognisable drive anomalies ?

(Note that with certain accessories added to the back end of the 'scope, it may not be possible for the OTA to reach the vertical before they make contact with the mount's base so remove all for the purpose of this test).

Assuming that the Alt. axis moves freely in both directions and you assess its clutch to be adjusted to the correct amount of tension so as to prevent the OTA from dropping under its own weight while at the same time not to be so tight as allow the drive motor to struggle, move on to checking the azimuth axis.

Rocking the mount base gently by hand from side to side, is there any excessive movement present ? A couple of millimetres either side is permissible but much more and this might be indicative of a problem.

Having checked for this freeplay, does the azimuth axis rotate a full 360 degrees in both directions under power with no sound anomalies which might suggest wear, missing gear teeth or slippage/looseness of the drive motor and thus overall only partial engagement of the drive mechanism ?

2) When you perform an "Auto Align", do you access the 90 degrees slew error to be in the altitude axis, the azimuth axis or both?

For example, when slewing to Sirius, the altitude axis will be raised from its original horizontal position by a certain amount but thereafter when the 'scope makes its second slew to Capella, it should be raised even more: Capella being at a higher altitude in the sky than Sirius.

Does this seem to be the case ? If so, then the Alt. axis is probably OK. This would therefore equally suggest that the problem is confined to the azimuth axis.

Overall therefore, if we can pinpoint whether the problem lies in any particular axis, I'm sure this would help in establishing the cause.

Hoping these thoughts help,
Best regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5659356 - 02/03/13 04:37 AM

Hi Lb,

Our posts seem to have crossed ! My, you get up early in the morning ! It's only ca. 9:30am over here in the UK !

Over and above what I've just suggested and in respect of your latest posts, I would first and foremost leave the GPS out of the equation. At this stage we are trying to determine where the fault is within your 'scope and the GPS is only an accessory. The 'scope, in full running order, will function with or without it. Therefore it is superfluous and indeed only a complication to the solution of this problem.

As to repair or selling, I can't advise. Being an Englander, I have no idea of your marketing structures.

Best regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5659729 - 02/03/13 11:00 AM

Hi Lb:

I think we need to clear up some possible confusion regarding the GPS you mention in the title of this post.

Do you indeed have a GPS unit on your scope? Note that the Nexstar 8 does NOT come with a GPS as a standard feature. A GPS would be an add-on for that scope, and I'm not even sure if one was sold which was compatible with that scope.

But if you did have one, it would be a separate box of some sort attached to the outside of the OTA or the mount, and it would have some cabling that connected it to the mount. Since the only connectors on that scope are the one in the handset cavity and the one on the bottom of the handset, I assume it would have to connect to one of those.

(Note that Celestron DID sell a model called the "Nexstar 8 GPS" which had GPS built-in, but it is a different mount than the one you have. It is a dual fork mount that is similar to the current CPC line of mounts.)

-Dan


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Midnight Dan]
      #5659909 - 02/03/13 12:37 PM

I believe the Celestron CN-16 GPS unmit was imtroduced for the Nexstar "i" series as an option.I have a Nexstar 5i with CN-16 unit on top of the OTA.Theree is no socket to plug the CN-16 cord into on the original Nexstar 8.

I seem to recall the HC asking for an "offset" during the intial alignment.That is a number relating to how many timezones away from UTC(Greenwich)'if that is set incorrectly the positions will be off .
The fact the error in pointing is consist makes me think something is incorrect in the numbers being put into the HC.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5660182 - 02/03/13 03:19 PM

Quote:

Hi Lb and good morning !

Some overnight thoughts.

1) Without attempting to make any alignment at all, have you checked that both axes rotate freely in as much as the altitude axis can be powered via the HC, from a point where the 'scope tube, (OTA), is almost resting on the base of the mount to the vertical and back again without any signs of slippage, or other recognisable drive anomalies ?

(Note that with certain accessories added to the back end of the 'scope, it may not be possible for the OTA to reach the vertical before they make contact with the mount's base so remove all for the purpose of this test).

Assuming that the Alt. axis moves freely in both directions and you assess its clutch to be adjusted to the correct amount of tension so as to prevent the OTA from dropping under its own weight while at the same time not to be so tight as allow the drive motor to struggle, move on to checking the azimuth axis.

Rocking the mount base gently by hand from side to side, is there any excessive movement present ? A couple of millimetres either side is permissible but much more and this might be indicative of a problem.

Having checked for this freeplay, does the azimuth axis rotate a full 360 degrees in both directions under power with no sound anomalies which might suggest wear, missing gear teeth or slippage/looseness of the drive motor and thus overall only partial engagement of the drive mechanism ?

2) When you perform an "Auto Align", do you access the 90 degrees slew error to be in the altitude axis, the azimuth axis or both?

For example, when slewing to Sirius, the altitude axis will be raised from its original horizontal position by a certain amount but thereafter when the 'scope makes its second slew to Capella, it should be raised even more: Capella being at a higher altitude in the sky than Sirius.

Does this seem to be the case ? If so, then the Alt. axis is probably OK. This would therefore equally suggest that the problem is confined to the azimuth axis.

Overall therefore, if we can pinpoint whether the problem lies in any particular axis, I'm sure this would help in establishing the cause.

Hoping these thoughts help,
Best regards,
Tel




Hi Tel,

1. Scope moves freely 360 degrees and holds its own weight with no problem.

2. Based from your Sirius and Capella example it appears the altitude axis is ok and the problem is with the azimuth axis.

I hope we can figure this out.

Thanks.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5660185 - 02/03/13 03:22 PM

Quote:

Hi Lb,

Our posts seem to have crossed ! My, you get up early in the morning ! It's only ca. 9:30am over here in the UK !

Over and above what I've just suggested and in respect of your latest posts, I would first and foremost leave the GPS out of the equation. At this stage we are trying to determine where the fault is within your 'scope and the GPS is only an accessory. The 'scope, in full running order, will function with or without it. Therefore it is superfluous and indeed only a complication to the solution of this problem.

As to repair or selling, I can't advise. Being an Englander, I have no idea of your marketing structures.

Best regards,
Tel




Hi Tel,

I am just a night owl I go to sleep late. I sometimes stay up just to watch Saturn.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Midnight Dan]
      #5660188 - 02/03/13 03:23 PM

Quote:

Hi Lb:

I think we need to clear up some possible confusion regarding the GPS you mention in the title of this post.

Do you indeed have a GPS unit on your scope? Note that the Nexstar 8 does NOT come with a GPS as a standard feature. A GPS would be an add-on for that scope, and I'm not even sure if one was sold which was compatible with that scope.

But if you did have one, it would be a separate box of some sort attached to the outside of the OTA or the mount, and it would have some cabling that connected it to the mount. Since the only connectors on that scope are the one in the handset cavity and the one on the bottom of the handset, I assume it would have to connect to one of those.

(Note that Celestron DID sell a model called the "Nexstar 8 GPS" which had GPS built-in, but it is a different mount than the one you have. It is a dual fork mount that is similar to the current CPC line of mounts.)

-Dan




Hi Dan,

My mistake I do not have a GPS. Thanks.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: BigC]
      #5660200 - 02/03/13 03:28 PM

Quote:

I believe the Celestron CN-16 GPS unmit was imtroduced for the Nexstar "i" series as an option.I have a Nexstar 5i with CN-16 unit on top of the OTA.Theree is no socket to plug the CN-16 cord into on the original Nexstar 8.

I seem to recall the HC asking for an "offset" during the intial alignment.That is a number relating to how many timezones away from UTC(Greenwich)'if that is set incorrectly the positions will be off .
The fact the error in pointing is consist makes me think something is incorrect in the numbers being put into the HC.




Hi BigC,

I wish I was entering the wrong numbers so that this headache would go away.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5660569 - 02/03/13 06:52 PM

Hi Lb,

I wasn't quite clear from your above comment, whether you detected any freeplay in the azimuth axis if you tried to rotate it from side to side by hand.

I assume there is none or very little and thus the azimuth axis cannot otherwise be rotated by hand. (?) Could you confirm this to be the case ?

Assuming then that the altitude axis is OK, as you've indicated by the relative elevations it made in respect of slewing to Sirius followed by Capella, and that you are absolutely convinced all your HC data entries, (Time, Date, Time Zone, Standard Time Confirmation, Lat./Long Co-ordinates) are sound and correct; then I think the time is approaching to open up the base of the mount for inspection. Are you happy to do this if necessary ?

Best regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5660592 - 02/03/13 07:11 PM

Quote:


Hi BigC,

I wish I was entering the wrong numbers so that this headache would go away.




Here's a crazy suggestion:

So, the darn thing is pointing about 90 degrees off. Do an experiment, use the wrong time, starting with maybe 6 hours earlier and see how close it gets...

Is there a local astronomy club nearby where you might be able to find someone to come and look at the scope? How far are you from Mobile Alabama?

Last ditch effort: Send me the controller and I will test it on my Nextstar 5.

Jon


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5660612 - 02/03/13 07:32 PM

Quote:

Hi Lb,

I wasn't quite clear from your above comment, whether you detected any freeplay in the azimuth axis if you tried to rotate it from side to side by hand.

I assume there is none or very little and thus the azimuth axis cannot otherwise be rotated by hand. (?) Could you confirm this to be the case ?

Assuming then that the altitude axis is OK, as you've indicated by the relative elevations it made in respect of slewing to Sirius followed by Capella, and that you are absolutely convinced all your HC data entries, (Time, Date, Time Zone, Standard Time Confirmation, Lat./Long Co-ordinates) are sound and correct; then I think the time is approaching to open up the base of the mount for inspection. Are you happy to do this if necessary ?

Best regards,
Tel




Hi Tel.

Yeah no freeplay when I tried to rotate from side to side. Yeah i am willing to do what it takes to get this resolved. I just dont want to damage any of the components, as I am not to handy.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Jon Isaacs]
      #5660620 - 02/03/13 07:38 PM

Quote:

Quote:


Hi BigC,

I wish I was entering the wrong numbers so that this headache would go away.




Here's a crazy suggestion:

So, the darn thing is pointing about 90 degrees off. Do an experiment, use the wrong time, starting with maybe 6 hours earlier and see how close it gets...

Is there a local astronomy club nearby where you might be able to find someone to come and look at the scope? How far are you from Mobile Alabama?

Last ditch effort: Send me the controller and I will test it on my Nextstar 5.

Jon




Hi Jon,

Thats an interesting idea by tricking the scope its a different time in the day and see how close it gets.

Ill research to see whats the closest astronomy club in my area.

I am basically 35 miles North of Miami, Florida. So i am probably atleast 500-600 miles from Mobile Alabama.

Thanks.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5660632 - 02/03/13 07:49 PM

This one looks good to me:

Southern Cross Astronomical Society

Jon


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Jon Isaacs]
      #5660771 - 02/03/13 09:32 PM

Update.

As suggested I did some experimenting with changing the time. I did an experiment for 8,7,6,5 and 6-1/2 hours before my actual time. At 6.5 hours before my actual time the scope is basically above Sirius but the altitude is off by approximatelly maybe 20 degrees higher ( I am guessing).

Maybe I need to experiment with my altitude?

Edited by Lbrasci (02/03/13 09:33 PM)


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5661130 - 02/04/13 04:36 AM

Hi Lb,

I'm still thinking but running out of ideas ! From what you've now reported, it's beginning to sound as if you will need an "on the spot" second opinion as Jon has suggested.

However, from your above experiment with time variation and the 20 degrees error, (now in altitude), in mind; can you tell us whether this was actually carried out at night with Sirius in view or by mock alignment during the daytime with a guesstimate of Sirius' position ? In other words, how did you specifically estimate the 20 degrees altitude error ?

Best regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5661210 - 02/04/13 07:10 AM

Hi Lbrasci:

Might be a dumb question, but are you sure you're entering "West" and "North" when you set your longitude and latitude?

Another thing to try is resetting the hand controller to factory defaults. This is done through the menu system, and is in the Utilities Menu.

-Dan


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Midnight Dan]
      #5661230 - 02/04/13 07:31 AM

Hi Dan,

I may be wrong but in looking at the Nexstar 8 manual (Mike Swanson's site), there appears to be no provision in Utilities or anywhere else whereby a factory reset can be made.

Access to the particular firmware version is also a little strange by apparently appearing first on the HC screen when the 'scope is switched on.

Perhaps have a look at this: (together of course with Lb). It indicates that there might have been a "runaway slew" problem with one particular version (?).

http://www.nexstarsite.com/Firmware/N58Firmware.htm

So saying, there is a feature within the Utilities section of the N8's HC which is apparently called "Demo" and it's supposed to: and I quote:

"This feature will test both the altitude and azimuth motors by slewing to randomly chosen co-ordinates in the sky".

Straw grabbing, I know, but might this perhaps contribute to highlighting this problem ?

Best regards,
Tel

Edited by Tel (02/04/13 07:32 AM)


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5661700 - 02/04/13 12:40 PM

Quote:

Hi Lb,

I'm still thinking but running out of ideas ! From what you've now reported, it's beginning to sound as if you will need an "on the spot" second opinion as Jon has suggested.

However, from your above experiment with time variation and the 20 degrees error, (now in altitude), in mind; can you tell us whether this was actually carried out at night with Sirius in view or by mock alignment during the daytime with a guesstimate of Sirius' position ? In other words, how did you specifically estimate the 20 degrees altitude error ?

Best regards,
Tel




Hi Tel,

I actually carried out the experiment at night (During the blackout of the Super Bowl football game) when Sirius was visible and 20 degrees was a guess based on it being approximatelly 1/4 of a right angle (90 degrees).


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Midnight Dan]
      #5661712 - 02/04/13 12:45 PM

Hi Midnight Dan,

I enter "W" and "+" when I enter longitude and latitude. I dont have an option to reset as per manual and as per conversation with celestron rep. Thanks.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5661721 - 02/04/13 12:50 PM

Quote:

Hi Dan,

I may be wrong but in looking at the Nexstar 8 manual (Mike Swanson's site), there appears to be no provision in Utilities or anywhere else whereby a factory reset can be made.

Access to the particular firmware version is also a little strange by apparently appearing first on the HC screen when the 'scope is switched on.

Perhaps have a look at this: (together of course with Lb). It indicates that there might have been a "runaway slew" problem with one particular version (?).

http://www.nexstarsite.com/Firmware/N58Firmware.htm

So saying, there is a feature within the Utilities section of the N8's HC which is apparently called "Demo" and it's supposed to: and I quote:

"This feature will test both the altitude and azimuth motors by slewing to randomly chosen co-ordinates in the sky".

Straw grabbing, I know, but might this perhaps contribute to highlighting this problem ?

Best regards,
Tel




Hi Tel,

I have not experience any runaway slew problems and "demo" works but I have no idea to where it is pointing.


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5661803 - 02/04/13 01:41 PM

Hi Lb,

I have to admit that I have no idea of the workings of "Demo" as it is not a feature contained in later HCs so can't comment on its usefulness. Presumably one programs it with RA/Dec co-ordinates and then observes its direction finding ability after sending the 'scope to this position. (?)

On the other hand, what is more beneficial about this particular feature over and above making a simple slew to any objectt following a successful alignment, I really don't know. The manual is not specific on that point.

But that aside, I now think that we've reached a point where there is little more to offer in terms of possible solutions to this and that this 'scope should, with no offence to yourself, receive a direct "hands-on second opinion". To me, its all beginning to point towards on board computer corruption, but ................. ?

Best regards,
Tel

Edited by Tel (02/04/13 02:16 PM)


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5663025 - 02/05/13 08:09 AM

Talking of a corrupted board, I am leaning more and more towards this as the cause of this problem for the following simple reason.

Consulting the Nexstar 8 and my old Nexstar 8i manuals, the "Two Star Align", (unlike the later SE method), does NOT call for any location, date or time/time zone entries. It merely relies on the positions of the two alignment stars selected by the operator.

Logically therefore, any erroneous data, (time, time zone, date, lat./long.), which may have been introduced into the HC, becomes irrelevant when making a "Two Star Align".

BUT even this method of alignment fails.

So, unless either or both of the two alignment stars chosen for a "Two Star Align" are wrongly identified, then I can only assume that the on-board computer program has indeed been corrupted.

What does anyone else think ?

Best regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5663341 - 02/05/13 10:51 AM

I had this problem when I first got my Nexstar 8. I had the telescope upsidedown when aligning. I flipped the tube over the other way and it aligned perfectly.

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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: R_S_C]
      #5663524 - 02/05/13 12:32 PM

Hi R.S.C.

Firstly, a very warm welcome to CN and to this Nexstar forum !

In response to your post though, yes, indeed a possibilty, except that Lb's image of his ''scope on page 1 of this thread, does show it to be correctly orientated so unless he's changing the tube's position .............. (?)

Best regards,
Tel


Edited by Tel (02/05/13 03:53 PM)


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5664284 - 02/05/13 08:34 PM

Quote:

Talking of a corrupted board, I am leaning more and more towards this as the cause of this problem for the following simple reason.

Consulting the Nexstar 8 and my old Nexstar 8i manuals, the "Two Star Align", (unlike the later SE method), does NOT call for any location, date or time/time zone entries. It merely relies on the positions of the two alignment stars selected by the operator.

Logically therefore, any erroneous data, (time, time zone, date, lat./long.), which may have been introduced into the HC, becomes irrelevant when making a "Two Star Align".

BUT even this method of alignment fails.

So, unless either or both of the two alignment stars chosen for a "Two Star Align" are wrongly identified, then I can only assume that the on-board computer program has indeed been corrupted.

What does anyone else think ?

Best regards,
Tel




Hi Tel,

Based on the 2 star align example the on-board computer is most likely corrupted. How is the on-board computer fixed or replaced? And who does it?


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5664662 - 02/06/13 05:24 AM

Hi Lb,

There's a number of issues here.

In the first place, with my living in England, I can't help you with any direct search for parts or outside repairers. All I can do is provide the instruction, (if you have not accessed it already), as to how the circuit board may be accessed.

In this respect, you should find this link useful.

http://www.nexstarsite.com/Book/Updates/N58Azimuth.htm

In removing the mount cover, you should not need to go beyond inspecting the single circuit board.

However, further thoughts before any disassembly.

If you can get anyone from a local Astronomical Society to make an additional "hands-on inspection", (i.e. provide a second opinion) I would recommend you do so.

Additionally, and again before any disassembly, the problem may lie, not with the circuit board contained in the base of the mount, but with the HC itself. (I speak from having had HC failure myself and as a consequence, had to replace the whole unit).

With this being an additional possibilty therefore, I'd recommend you check and gently clean the metal contacts on the HC.

I appreciate the contacts within the female receiving plug contained in the niche of the mount arm where the HC rests are virtually impossible to reach, but perhaps a blast fronm a contact cleaner aerosol would help as would similar application to the male contacts on the end of the HC's cord.

Having cleaned these, replug the HC into the mount arm and re-test the 'scope with a "Two Star Align". You might just be lucky !

On the other hand, if you do have to enter the base of the mount to expose the single circuit board: before all else, check all wiring connections. It is not unknown for wires to loosen or detach themselves within these mounts.

That's the best I can offer, Lb. For help in accessing parts and repair if necessary, perhaps some of your countrymen here can assist. (?)

Best regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5664724 - 02/06/13 07:11 AM

Hi Lbrasci:

One more possible straw to grab at. On the Nexstar site, there is a reference to corruption of the lattitude/longitude values of adjacent stored location numbers:

http://www.nexstarsite.com/OddsNEnds/N58Locations.htm

You might want to look through the locations stored on your scope to see which ones have been used. Perhaps that's the problem?

-Dan


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5665062 - 02/06/13 11:46 AM

Quote:

Additionally, does your hand controller version ask for a latitude co-ordinate followed by a choice between North or South and a longitude co-ordinate followed by a choice between East or West or, does it require you use a "plus/minus system.

Here I quote what Mike Swanson has to say on this subject from his book, "The Nexstar User's Guide".

Quote:

If your version of Nexstar asks for a + or - for latitude, + is north latitude.

Note that on the original Nexstar 5 and 8, storing your longitude and latitude in adjacent "stored locations" will corrupt the entries. This results in the Auto Alignment procedure missing the two alignment stars.

To prevent this problem, only store and use longitude and latitude in locations 0,4,8 or 1, 5, 9.

Does this information perhaps help ?

Incidentally, what HC version are you in fact using ?

Best regards,
Tel




Hi Dan,

This has become an exceptionally long thread so it has been an effort in itself to keep abreast of that which has gone before, but I did cover the possibility of adjacent numbering Lat./Long. causing programing corruption. I have though since dismissed it in view of the fact that a straight "Two Star Align" requires no data input, (see above), but still fails to align successfully.

Looking back though over the thread, and in the same vein in as much as not recalling what has gone before, I now see that Jon Isaacs offered to check out Lb's HC on his N5.

This, in my opinion, might be a good move if cleaning the HC's contacts proves unsuccessful and no loose wiring is found. This would perhaps highlight whether the problem lies more likely with the HC rather than the circuit board. (?)

What do you think ?

Best regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5665341 - 02/06/13 02:04 PM

Hi Tel:

Oops! Sorry, I missed that part of the thread.

Yes, I think taking advantage of Jon's offer to test out the handset would be a good idea. I agree that it's the more likely culprit.

-Dan


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Midnight Dan]
      #5665567 - 02/06/13 04:02 PM

No worries, Dan !

I'm sure you'd agree, it can be one heck of a job to keep track of exactly what has been said and actioned within these more technically detailed and often more protracted threads !

Best regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5665708 - 02/06/13 05:30 PM

Tel
The original 5i needs to be set up under the menu- scope set up-time DST or Std- Lat/Long the OT should be facing aprox N and level matching up the alignment points on the tower and arm before a 2 star alignment is done. The 5i will remember some of this data but even if left in hibernation will not remember time and date upon wake up.
I do a scope set up before alignment if tracking or goto isn't behaving . Sorry, if I'm rehashing something already covered but the 5i is pretty unforgiving if the 2 star alignment is going to work.
Be Well
Grey


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5665735 - 02/06/13 05:48 PM

On a side note, is a celestron 6/8SE mount compatible with my original OTA?

Also, are the new SE hand controllers compatible with my mount?


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5665743 - 02/06/13 05:57 PM

I might have to take Jon up on his offer to test out hc.

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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Greyhaven]
      #5665784 - 02/06/13 06:18 PM

Hi Grey,

My apologies but I'm not sure I'm clear on what you saying here so let me perhaps explain my reasoning.

I own a Nexstar 8i which I bought in '06, (although I have since transferred its OTA to a GEM in my garden "Dome"). I'm therefore familiar with the old "Face North and align the index marks on the tower" routine, although I upgraded the N8i's HC in '08 to that of the SE series thus making the index marks redundant !

However as I understand the older alignment processes, (which I once conducted): --- from consulting the Nexstar 8 manual, (source Mike Swanson's website), and my own N5i/8i manual, plus Mike's book, "The Nexstar User's Guide", all of these indicate that while time, date, daylight savings or ST, time zone and latitude/longitude entries are necessary prior to performing an "Auto Two Star Align" with these older 'scopes; none of these entries are necessary when conducting a "Two Star Align".

True, I think that while these necessary entries may well have been entered/revised at some point whenever an "Auto Two Star Align" had been performed and that time zone and Lat./Long. co-ordinates would have been retained, (whereas time and date will not); such retained information is ignored, (according to the manuals et al) when a simple "Two Star Align is performed.

This alternative alignment method apparently attributes its success merely by recognising only the positions of the two chosen alignment stars relative to each other.

My reasoning is such therefore, that as Lb's Nexstar 8 had failed to align despite employing BOTH methods, the input data necessary to perform an "Auto two Star Align" cannot be playing any part in causing the failure.

Does this linr of reasoning make sense or are you thinking along other lines ?

Best regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5665801 - 02/06/13 06:26 PM

Quote:

On a side note, is a celestron 6/8SE mount compatible with my original OTA?

Also, are the new SE hand controllers compatible with my mount?




Hi Lb,

The 6SE/8SE mount will accept your N8's OTA willingly but you will need to attach a Vixen dovetail rail to it.

The newer 6SE/8SE HC is not compatible with your existing mount and your existing HC is not upgradeable.

Best regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5665879 - 02/06/13 07:20 PM

I am just thinking worst case scenerio at this moment.

Does anyone know how much a used celestron 6/8SE mount/tripod cost or what would be a fair price? I saw a used one going for $325 plus shipping which seemed rather high, brand new they go for $419 including shipping.

Thanks for the info Tel.

Edited by Lbrasci (02/06/13 07:40 PM)


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5666036 - 02/06/13 09:20 PM

Tel
My copy of Mike's book is a 2004 addition on pg. 76 Mike states for auto align on some models I think he means non GPS the longitude ,lat,time and date have to be entered. The date has to be in US format mm/dd/yyyy 1 level tripod 2 point telescope Roughly North.Insert a high power eyepiece , select Auto Align when prompted to point north and level if you can see Polaris, use the HC to center it in the finder this will get you to be pointing directly to cel.North now bring your two index marks together. Press ENTER At this point, on the GPS models you will find a GPS link may be established automatically providing location, date and time. Press ENTER if the you agree with the GPS. A star's name will appear in the HC
If this star is not in a visible spot, press any arrow button to cancel the slew, press UNDO and the next alignment star will be chosen by the HC and a slew will be in progress once the scope stops use the direction buttons to center it in the finder and press Enter, using arrows carefully center the star in the center of the eyepiece and press ALIGN repeat this same procedure for the next star that chosen by the HC If the stars you centered on were the correct ones and all your data entries were correct your HC will tell you the alignment was a success. I hope this helps clarify my earlier attempts at explaining Auto Alignment and I hope Mike Swanson doesn't mind my interpretation of his fine book. There are 5 alignment choices on my 5i with the original HC GPS/QUICK ALIGN/EQ SOUTH/EQ NORTH/2 STAR ALIGN and AUTO ALIGN. My method of choice is 2 STAR ALIGN.
Now I've got to read this over and see if it makes more sense reading it than writing it did. The only Auto part about the auto align from regular 2 star alignment is you choose your alignment stars from a list that you scroll though on the HC.
Be Well
Grey

Edited by Greyhaven (02/06/13 09:26 PM)


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Greyhaven]
      #5666445 - 02/07/13 04:12 AM

Hi Grey,

My copy of Mike's book appears to date from 2005, (a second printing from presumably the original of 2004). I don't suppose though, that too much changed.

As to the various alignment techniques, yes, five are covered, namely, GPS, Auto two Star, Two Star, Quick Align, EQ North and EQ South, whereby for the Auto Two Star Align on page 76, ("All Models" according to my copy), it is indeed necessary to enter such data as time, (DST or ST) date, time zone plus lat./long. before proceeding with the alignment.

However, if your copy is the same as mine in this respect and you refer to the Two Star Align method described on page78, you'll see that according to Mike, the above data entry is not required, hence my conjecture that as Lb has used both techniques in his attempts to align his 'scope and unfortunately failed with both, correct or even mis-entered data should not be contributing to his problem.

It's just an idea and very probably a straw grab on my part, but what do you think ?

Best regards,
Tel


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Tel]
      #5666604 - 02/07/13 08:07 AM

Tel
I guess as we say in the states this problem calls for a greater mind than mine. I'll have to get off a quick post to the "Dear Abbey" column for guidance.
Next few days will be involved in cleaning the 24+ inches of snow expected here Thursday night through Saturday afternoon. It should be fun with the 75MPH winds that are coming with it.
Be Well
Grey


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Re: Nexstar 8 Original Silver Align/ GPS Problem new [Re: Lbrasci]
      #5667199 - 02/07/13 02:31 PM

Quote:

I am just thinking worst case scenerio at this moment.

Does anyone know how much a used celestron 6/8SE mount/tripod cost or what would be a fair price? I saw a used one going for $325 plus shipping which seemed rather high, brand new they go for $419 including shipping.

Thanks for the info Tel.


You'd be better buying the whole 8SE because your original silver 8 will not fit on the 8SE mount-the original has no dovetail system like the current models.
I'm sure someone here can tell you how to add a dovetail to the older tube.

I still think there is a fix for what you own now IF the error is consistent.If the error is random there might still be just a loose connection or failing solder joint making intermittent contact.


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