133 replies to this topic

[Will2007]

Hello again Andrew,

The 'scope is now waiting for a good night in Massachusetts (just N. of Boston). I am anxious to start planetary photography again; the viewing in FL became disappointing as the weather warmed.

I definitely owe you a Fosters!!  I tried to send you one, but the keyboard became sticky... 

Cheers!

[Will2007]

Let the FUN begin... :-(

That 'good night' happened and I could NOT get the 'scope to align. (The move from FL was in a padded Meade Box inside a passenger auto.)

Now - a few weeks later after a trip to the UK - I have it setup inside the garage, using Skyview with the phone tightly held to the primary dust cover. I select an alignment star, then slew the scope so that star aligns with the target in the Skyview display.

I am getting a consistent "alignment error" message.

I just gave up tonight.

Maybe I need a sensor calibrate action? Any other first action suggestions?

Couldn't find any Theakston's brew, but Stella was pretty good (no Fosters either!)

Forecast is for rain next several days  :-(

Thanks, Will

[OzAndrewJ]

Gday Will
 

I select an alignment star, then slew the scope so that star aligns with the target in the Skyview display.

I have no idea how that would work.

And how far did you have to slew to centre the second star that way????

The error there is what determines a failed align.

 

To do an indoor test, boot it up and let it fix ( or enter data manually )

Ensure the locations are correct. ( esp based on your move )

Set the mount to AltAz home and do a dummy align

When the mount slews to the first star, ue your plantarium app

toi see if its roughly correct.

Thats the best you can really do indoors.

 

Andrew Johansen Melbourne Australia

[Will2007]

G'Day Andrew,

I kept pressing the enter key - oops!!

Az was within 12 min; El was off 4 degrees which is probably "reasonable"?

I had to enter a city nearby as the GPS wouldn't get a fix inside the garage.

I think I need this rain to stop and try again!

Thanks, Will

[OzAndrewJ]

Gday Will
 

El was off 4 degrees which is probably "reasonable"

How do you know it was off by 4deg????? ( if you cant see any stars )

If you are worried, then do the indoor slew test on the Alt axis

to see if it reports moving the correct distance,

when you move a known "mechanical" distance.

Andrew Johansen Melbourne Australia

[Will2007]

Hi Andrew,

Well, that was using SkyView...

Obervation: last spring I found a way using a IPhone mount (intended to mount phone on an eyepiece) to attach the phone to a small finder on my Celestron (which my daughter now will not give back!).  I found that the finder and phone display (using Skyview) were amazingly close - so close that I suggested the manufacturer advertise the product as a 'poor-man's' Telrad.

I never heard from them; they most likely thought I was crazy (occasionally true).

Your point is well taken, however.  There is always opportunity for error while holding a device against the mirror "bell" at the back of the 'scope.

From the forecast, there MAY be another opportunity for a real test in 5 or 6 days.

Take care, Will

[Hunain Amjad]

Hello Joe,

Welcome to the world of Meade equipment! While the Meade Autostar hand controller is commonly used for the alignment process, there is indeed a way to perform the alignment using computer software for your LXD75 mount.

One popular software option for Meade telescopes is Stellarium, a free and open-source planetarium software. Stellarium allows you to control your telescope through the computer, including the alignment process. You can select alignment stars and carry out the alignment directly from the software.

To use Stellarium with your Meade LXD75 mount, you'll need to connect your computer to the telescope using a compatible serial cable and ensure that the necessary drivers are installed. Once connected, you can access the telescope control panel in Stellarium to initiate the alignment procedure.

For a detailed step-by-step guide on using Stellarium with Meade telescopes, you can visit the site telescopesgeek.com There they have an article specifically on connecting and controlling telescopes with computer, which will provide you with all the information you need. You can find it here: https://telescopesge...pe-to-computer/

I hope this helps you align your Meade LXD75 mount using computer software. Enjoy exploring the wonders of the night sky!

Best regards,
Hunain Amjad

Edited by Hunain Amjad, 27 June 2023 - 01:31 PM.

[DerroL]

Hi Andrew,

I have been using your Jack of all trades software to replace my defunct handbox for the LX200 mead. The software works nicely but my computer setup is very clumsy. I am using windows running on a Mac and the menu items such as slew controls require mouse operation. So I find myself grappling in the dark with a laptop and mouse pad to slew my scope during alignment procedures. Incredibly awkward.

What I am aiming to do is devote a small touch sensitive tablet to the task of being a de facto handbox. Microsoft "surface" computers running windows are an overkill for the task and not really suitable because I am looking for something to be hand held.

 

Does your app run on an android operating system?

 

Ive never used android systems so I dont know if programes can be compatible across windows and android.

 

thanks

Derek

[OzAndrewJ]

Gday Derek

My app doesnt run on Android but if you have an android smart device

the following link may give another option

https://groups.io/g/asiie

It uses the Hbx port to connect, so leaves the rs232 ports free for other uses.

 

Andrew Johansen Melbourne Australia

[Will2007]

Hi Andrew,

Did not have a good summer in New England, it rained frequently and was cloudy when not raining.

 

Left the LX200 up North and picked up an ETX-90EC with tripod for a donation to my local Florida Astronomy Club.  It came with an Autostar controller - one with two connectors on the bottom.

everything seems to work well, but there are differences from the LX200 setup, so I have a couple of questions...

Is there a battery in the Autostar?  Date is remembered, but not time (re-started after 15 minutes).

Guessing no GPS here; so set Lat-Long manually?

Can I use an RS232 cable to see various settings as in the LX200?

 

Hope this finds you well.  Take care, Will

[OzAndrewJ]

Gday Will

No battery in the handset

Date is actually "last date" used.

There is no clock unless you have an LNT unit, ( but thats not normally for ETX-90s )

so time resets to 8:00PM and date to "Last Date" on reboot.

The basic ETX-90 has no GPS but you can get a third party plugin ( StarGPS )

if desired.

You can connect to a PC using a Meade 505 cable

This cable is wired the same as the 507 cable used with the LX200s

but it uses a 4p4c plug instead of a 6p4c like the LX200s

so you wil need to get a different cable/adapter

If you update the firmware to the latest patched 43Eg

it will give you full remote handset functions etc for control by PC

as well as fix lots of bugs and add a few enhancements.

 

Andrew Johansen Melbourne Australia

[Will2007]

Hi Andrew,

At last a clear night!! I setup my "new" ETX and tried an "easy" alignment, but one of the stars was close to a streetlight, so it was 'close' at best.

The scope stayed on the Moon for a while, then I moved to Saturn.  That tracking did not do well.  I noted significant play in the horizontal axis (Alt-Az mount) when changing direction.  Doesn't sound good.

I suspect a gear has loosened up, or possibly been damaged during shipment during the previous ownership. I think it's inspection time :-(

Have you opened an ETX drive? Are there any nasty surprizes?

 

Thanks, Will

[OzAndrewJ]

Gday Will

I have never opened an ETX90 and there are several versions.

( Very early ones used simple plastic journal bearings and had a lot of lash , mainly DEC

but drive training allowed them to be used "manually" )

I have an ETX-125 and the bottom plate comes off easily and you can see whats in there

so would assume the 90 is similar, so thats first.

There are lots of photos in Weasners site

http://www.weasner.com/etx/menu.html

and googling can find a lot, but the main reason for lash is

1) bad mesh in the worm to wormwheel

2) loose bearing

3) endplay in the worm bearings

 

Andrew Johansen Melbourne Australia

[Thrifty1]

Have you opened an ETX drive? Are there any nasty surprizes?

 

Thanks, Will

There are a few variations of how they made the ETX drives.  The basic engineering is the same but some had more metal in things such as the worm gear support while others used plastic.  All of them that I have seen used plastic screw posts for the screws that held the gear boxes in place. These tend to crack / fail and can cause the gear box to ship around when slewing.  But pretty much anything can be repaired.  I use a 2-part epoxy to fix any broken parts and add some sort of metal to any repair to make it stronger than the original.  

 

Post a photo of what you have inside when you open the base.  It is very easy to remove the 3 screws on the bottom and then remove the base cover.  Be careful as the wires leading from the circuit board to the battery compartment are fairly short.  I lay the telescope on its side and tuck the cover you remove under the side of the base when repairing an azimuth drive.  

[Will2007]

Hi Randy,

Well, I ALMOST had it together.  I had to remove the gearbox again as it seemed the first spur gear - which contacts the motor gear - was rubbing on the case.  When I originally removed the gearbox, two small O-rings came out too, but it wasn't clear exactly where they belonged. So during the first re-assembly, I installed the O-ring below the shoulder of the shoulder washer (see photo).

I do now believe these O-rings belong between the gearbox and the standoffs protruding from the base.  

 

Comments?

 

My original disassembly of the gearbox was hampered by one of the shoulder washers being swaged over by (possibly) excessive torque on the screw (the one nearest the coarse spur gear on the worm gear shaft).  I finally removed the part and trimmed it with a razor knife.

I found that the gear which drives the coarse spur gear (on the worm gear shaft) moved because it's shaft was loose. The shafts are held in place by "no gap" fitting of the top and bottom.  BUT, that excessive torque had warped the plastic parts.  :-(

 

After spreading a small amt of crazy glue using a needle on the gear shaft retaining area, i reassembled the gearbox, but that wasn't enough!  So... I applied a drop into the case gap and that helped. (see last  photo)  

So, my last question is  (drum roll please) : where do those O-rings belong?

[Couldn't upload last photo :-(  ]

Tnx Will

 

Update: The results are in!  I can now train both drives.  The ETX needs a metal gearbox, but this repair significantly improved the system. Can't wait for the next clear night!   -Will

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Edited by Will2007, 24 December 2023 - 01:03 PM.

[OzAndrewJ]

Gday Will

OK, cant help for a 90 but the 125s i worked on have orings

between the Gbx and casting

Andrew Johansen Melbourne Australia

 

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[Will2007]

G'Day Andrew,

I strongly suspect that is where those pesky O-rings belong on the 90 also...

 

Tnx, Will

[profhuster]

For a detailed step-by-step guide on using Stellarium with Meade telescopes, you can visit the site telescopesgeek.com There they have an article specifically on connecting and controlling telescopes with computer, which will provide you with all the information you need. You can find it here: https://telescopesge...pe-to-computer/

This link appears dead. Do you have another reference?

[Blink Too Fast]

Gday Aaron

My app is at

http://members.optus...om.au/johansea/

That said, if its only the LCD screen that has died, there are drop in replacements now available

( just search this forum for "Formike"

and a new Android based phone app is out to replace the handset itself

https://www.cloudyni...on-users/page-3

Sooooo, several options

 

Andrew Johansen Melbourne Australia

Well this sounds just what I need.

 

I have an early LX90 EMC.

I tried autoguiding for the first time this evening.

Set it up in the living room.

Plugged the USB -> RS232 cable into the mount.

The 497 burnt up in a puff of smoke.

 

Hrmm.

 

Let me see how I get on. Fingers crossed!

[OzAndrewJ]

Gday Blinktoofast

The Android app only works on the LX200 ( ASII ) type mounts

as their handsets are dumb button boxes

My app and some others can remotely drive a 497/497EP/Audiostar

but the handset has to be functioning, including the rs232 port.

 

Plugged the USB -> RS232 cable into the mount.The 497 burnt up in a puff of smoke.

Where EXACTLY did you plug the cable in

( Please say it wasnt the Aux port on the control panel????? )

Even if you did that, i am not sure how it would fry the 497

unless it created a ground loop.

In that case, you may be lucky and have only blown an inductor

near the port in the hbx, but you are going to have to open it up and see.

 

Is the cable a genuine Meade 505 cable ( ie properly wired??? )

 

Andrew Johansen Melbourne Australia

[Blink Too Fast]

Gday Blinktoofast

The Android app only works on the LX200 ( ASII ) type mounts

as their handsets are dumb button boxes

My app and some others can remotely drive a 497/497EP/Audiostar

but the handset has to be functioning, including the rs232 port.

 

Where EXACTLY did you plug the cable in

( Please say it wasnt the Aux port on the control panel????? )

Even if you did that, i am not sure how it would fry the 497

unless it created a ground loop.

In that case, you may be lucky and have only blown an inductor

near the port in the hbx, but you are going to have to open it up and see.

 

Is the cable a genuine Meade 505 cable ( ie properly wired??? )

Wow!
That was a fast response to my response to a 3 year old post!

 

The LX90 was on batteries only, not an AC adapter.

The cable is a USB-C -> RS232 with a an RJ10 plug suitable for the 497 handbox. It uses a CP2102 USB -> serial chip.

I have previously used this cable to update the 497. It is not an original Meade.

 

The LX90 base has four sockets. Leftmost RJ10 labelled AUX; RJ45 for the 497; 12v in; on/off switch; rightmost RJ10 labelled AUX.

I plugged the USB cable into the leftmost AUX RJ10 on the base.

 

I chose ASI ASCOM from PHD2.

The mount slewed. Then stopped. Then I could smell burning. The 497 was hot to touch and no longer works. The hot spot seems to be behind the left hand side (as we view from the front) of the LCD.

 

I am comfortable opening and modifying electronics. For example, I am the same BlinkTooFast as the author of this thread modifying 1980s/90s CD players to do things outside their design briefs.

Edited by Blink Too Fast, 06 February 2024 - 09:40 PM.

[OzAndrewJ]

Gday Blinktoofast

 

That was a fast response to my response to a 3 year old post!

Doesnt matter how old the original post was as replies just appear at the top of the list :-)

 

I have previously used this cable to update the 497

OK, so we assume the wiring is correct

 

I plugged the USB cable into the leftmost AUX RJ10 on the base

 

The rs232 cable should only ever be plugged into the 4p4c socket in the base of the handset.

The AUX ports are wired totally differently, and have a full +12V pin in them.

As such, plugging the converter into the AUX port has created a return loop of unknown properties

ie looking into the handset port with tab on top

pins left to right go   Rx, Tx, N/C, Gnd

This port is a passive port with Tx and Rx going to a max232 to convert them to TTL

Looking into the AUX port with tab on top

pins left to right go   Gnd, Data, Clock, +12V

Data and clock are TTL level signal lines and +12V is supplied by the mount

to power whatever is plugged in.

Sooooo, you have put +12V into the ground line of yr converter

and the converter Rx is being tied to the mounts ground.

No idea what really happens there

Time to open it up and clean away the soot.

If you are lucky, it will only be an inductor ( high freq filter ) that blew

( and many have done that )

Andrew Johansen Melbourne Australia

[Blink Too Fast]

Doesnt matter how old the original post was as replies just appear at the top of the list :-)

Thanks 

 

Time for the screwdrivers

[Blink Too Fast]

Time to open it up and clean away the soot.

If you are lucky, it will only be an inductor ( high freq filter ) that blew

There is no visible damage.

 

The hotspot outside the case (left of the LCD), was exactly where the component at the top-right of this photo that looks like a flat transistor on a heat sink.

 

Labelled LM2931S, which is a voltage regulator, which is consistent with your explanation of sending 12v through a TTL circuit.

 

Ordered 5x TI LM2931S to be with me Thu-Sat.  USD15 inc shipping.

 

What sort of person puts the same RJ10 socket on a 12v supply outlet and a 5v control inlet?

Good thing it didn't trash my PC, I suppose.

 

[OzAndrewJ]

Gday Blinktoofast

 

I have not heard of the 5V reg dying as a result of this,

normally a trace in the control panel burns or an inductor

near the sockets blows up.

If you have a multimeter, check the resistance between

+5V rail and ground to see if it shows a short circuit

If it does, it could be ANY chip or part on the 5V rail

and finding that "in circuit" can be a horrible job.

One ( non technical ) way of testing is to power the board

and then use a fingertip to see what chips get hot.

( Having a thermal imaging camera is best, but they are expensive )

ie it may be another shorted component on the board is dragging down the

5V regulator and causing it to overheat.

Andrew Johansen Melbourne Australia