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Keeping a Classic LX200

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#1 E Sully

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Posted 21 April 2018 - 05:24 PM

The LX200 Classics are fairly old now.  A little maintenance can be worthwhile. 
One of the most important items is the capacitor in the Controller.  This is the one that can cause the biggest problem.  If you think your controller is bad due to a capacitor burning out, that can be a problem if it melted the internal ribbon cable. If you open up your controller you can get an idea if it is damaged.
First remove the 4 phillips screws on the back of the control paddle. Inside you will see the back of the circuit board. Remove the 4 phillips screws I have highlighted. You can then partially separate the back circuit board, and you can see in my picture the replacement blue capacitor I installed in position C2. If the ribbon is not damaged, replacing C2 should be done. As you can see in my last picture, I put a piece of fiberglass between my replacement capacitor and ribbon for future protection.
If the ribbon cable above is melted from the old capacitor burning out, repair can be a problem. I do not know of anyone with a replacement ribbon cable. Naturally, the other capacitors on the motor and main circuit boards should be addressed.
How about a look inside the base.  It does not take much to separate the forks and base to check on the gears and bearings. All you need are a couple of hex wrenches. Remove the center cover plate from between the forks. Then remove the hex bolt and washer in the valley. After that it is just a matter of pulling the 2 apart. My 8" is easy to do alone. Larger scopes may need 2 people.
Now you have access to both RA upper and lower bearings, RA main and worm gears. It makes it easy to clean and lubricate as needed.  Gently lower forks back on spindle while rotating lightly to engage worm and main gear.  The hex screw and washer should be snug, not too tight.  Adjusting worm and main gear play to be done later.
 

 

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  • LXBearing01.jpg
  • LXBearing02.jpg

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#2 E Sully

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Posted 21 April 2018 - 05:26 PM

The RA and Dec gear play can be adjusted. RA is doable by removing the control panel, but I find it helpful to also remove the base cover plate. Not bad on my 8", but again you would need at least 2 people for a 12".  Undo the 4 screws holding the control panel.  Pull the panel forward a little bit, then use a small screwdriver to remove the connector on the ribbon cable to free the control panel. This is a good time to replace the button battery. If you decide to open the base also, remove the 4 phillips screws and 2 smallest hex screws. Do not loosen the other 2 hex screws next to them. They hold the heat sinks to the circuit board. Nothing bad will happen if you undo them, it just isn't necessary.
Now looking inside, and you can see the small circuit board on the RA motor assembly. Naturally the small hex screw to adjust the worm gear play is under this board. Loosen the hex screw a little and rotate ccw till you can access the hole for the adjustment screw. You can remove the hex screw if you like, make sure the small insulating rubber under the circuit board stays in place. In my slightly blurry picture, you can see the hex wrench inserted into the adjustment screw. Meade specifies 1/16" of play. Turn the wrench till you get a small amount of play when pushing the worm gear away from the main ring gear. Too much gap and you will have excess play and possible skipping.  You do not want the gears to be snug against each other, too much friction will wear the gears and strain the motor. The last 2 pictures are the view with the bottom plate removed. Not necessary, but makes it a little easier.

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  • CntlPnl01.jpg
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  • Ra01.jpg
  • Ra02.jpg
  • RA03.jpg
  • Ra04.jpg

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#3 E Sully

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Posted 21 April 2018 - 05:29 PM

The Declination gears are easy. Unscrew the clutch knob and remove.  Remove the hex screws holding the plastic cover.   Now you have access to the Dec motor, gear, and clutch plate.  The declination motor is held in by 2 hex bolts.  If you wish to remove it, undo the 2 bolts and disconnect the electrical connector inside the fork arm.  Use caution not to damage the small wires or led's for the encoders.  Also be aware of the spring inside the hinge.  The declination clutch plate and main gear can be removed for cleaning if desired. 
After cleaning and greasing, adjust play between worm and main gear.  To set the gap, put the clutch knob back in so the main gear is snug.  It can be difficult to get the hex key into the adjusting screw.  You may be able to modify a hex wrench to adjust with assembly in place, but  I did it the hard way.  I tweaked the screw with the motor assembly out, install, check clearance, and repeat till 1/16" gap was reached.  Be careful not to lose the small tension spring.  When you are close, it only takes small turns to get it set.

Attached Thumbnails

  • Dec01.jpg
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#4 rferrante

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Posted 22 April 2018 - 12:11 PM

This is great info E Sully, well presented.

 

You mentioned there was no replacement available for the ribbon cable above, however I was able to purchase a replacement keypad from Ron Sampson last year, for around 50$, which included the ribbon cable and adhesive keypad, along with instructions for removing the original one. My hand controller had died due to the signature C2 failure-burns-hole-in-flex-cable issue. Ron's replacement keypad saved my LX-200.

 

I appreciate Ron for continuing to make these available (hopefully he still is), and all of the others who perform repair services or in any other way continue to support the LX200 Classic scopes.

 

I attached a photo of the replacement keypad on my hand controller, notice it says "Classic MHC" at the top instead of "Meade".

Attached Thumbnails

  • LX200_HC1.jpg


#5 E Sully

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Posted 22 April 2018 - 04:02 PM

That MHC cover looks good.  From what I have read lately though, Ron Sampson has been out of touch since December.  No one has been able to get a response from him in the last 4 months.


Edited by E Sully, 22 April 2018 - 04:02 PM.


#6 Starkid2u

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Posted 22 April 2018 - 07:37 PM

Well, Mr. Sully, as a proud owner of an 8" LX200 Classic, I really appreciated that you did this. Fortunately, I had someone braver than I take care of all this for me! But it's good to know that someone can now reference this to help themselves out! Great posting!!!

 

STARKID2U



#7 E Sully

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Posted 24 April 2018 - 11:07 AM

Let me just add the problem capacitors with locations of the main culprits.

Make sure any capacitors you change do not short out against the circuit boards.  Use caution not to damage the boards when removing the old capacitors.

C1 in the power panel, unscrew 3 retaining rings and separate the front cover.
C2 in hand controller
C8 in the main board
C1 on each motor controller (x2)

 

 

Attached Thumbnails

  • CntlCap01.jpg
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  • Cap01.jpg
  • Cap02.jpg
  • Dec005.jpg

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#8 E Sully

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Posted 25 April 2018 - 03:40 PM

This was posted on another thread, http://clearline-tech.com/index.html

I ordered a motor and calibration board.  Motor board will be a spare, but I wanted to try out the calibration board to check the potentiometers.  I was going to try another method that uses a voltmeter and adjusting to 2.42 volts, but this calibration board seems a lot easier than trying to connect leads to the small pins on the motor boards.



#9 E Sully

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Posted 30 April 2018 - 09:08 AM

I received both the replacement motor board and calibration board. Both look well made. I used the calibration board to check the potentiometers and it works very nicely. The leds indicate if any adjustment is needed and which way to turn it to get the board correctly set. If you give it a try, make small changes. I recommend marking the original positions of the pots before making any changes.  It takes a very light touch on the adjustment screw. If you overturn, you may see a runaway, but a quick turn back and it will settle in again. 
On my original board with replacement capacitor installed there was a close fit, mainly due to the height of the capacitor I installed. The pin connector did not sit flush, but still made enough contact.



#10 E Sully

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Posted 12 May 2018 - 03:48 PM

What else can one do to an older LX200 with rainy spring weather?  I decided to try the Peterson Engineering EZ Focus Kit.  While it never bothered me much, it does take a bit of fiddling to get a sharp focus.  There is a fair amount of play in the stock focuser.

I ordered the kit, and it arrived soon after.  It contained 2 roller bearings, a custom stainless washer, grease, allen wrenches, grease, and a bolt that is needed on 10" and up scopes.  It is designed to eliminate the play from the nylon washers used in the stock setup.

The directions are good, and installation went well.  I was very happy with the results.  Movement of the focuser is very smooth, and almost all of the play was removed.  It is a lot easier to bring things into sharp focus now.

While not a requirement if you are doing visual, it was worth it to me.  If you are into AP, then I would say definitely go for it.



#11 slabslayer

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Posted 16 May 2018 - 07:06 PM

Love the Peterson kit. Did mine 2 years ago. And now I added a feather lite electronic micro focuser since I want to delve into ap. But I wasn’t as brave as you, when I had electronics issues I upgraded everything to George Dudash’s kit. It has been great. I was too afraid to attempt that myself. I can do plug and play but that’s about it. My 10” LX200 is an f/6.3 scope so I didn’t want to get rid of it since I’m wanting to get into ap. Also did the bobs knobs and haven’t regretted that either!

#12 E Sully

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Posted 17 May 2018 - 10:26 AM

Your 10" f6.3 should work well for AP.  Good luck with it.

While I bought Bob's Knobs, I decided not to use them.  There is a clearance issue with the cover.  I did not want to risk pressure on the corrector since they extend above the lip of the OTA, and need to bend the stock cover to clear them.  The 8" is not hard to adjust by yourself using an allen key compared to larger OTA's.  Also, the scope holds collimation well, I have only adjusted collimation twice in the 18 years I have had the scope.

The Dudash kit is a nice option if the original controller or main board is damaged. I actually like the original controller over the Autostar for my Classic.  If the need comes up in the future though, I would spend the money on his kit.



#13 slabslayer

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Posted 18 May 2018 - 05:59 PM

My controller had quit working properly. I liked the old one as well. But the ports on my scope would stay powered but my controller wouldn’t respond. And getting into ap that was a major problem. I did it over a year ago and couldn’t be happier. Just recently got the ap equipment and read enough to where I thought I can try the beginner stuff.

#14 orionsbelt_UK

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Posted 23 September 2019 - 01:24 PM

Mead LX200 Classic issues with replacing capacitors and Hand Controller - revision 3.21

 

As my scope is over 20 years old I have been successfull replacing the failing 6.8 MicroFarad capacitors. (I am retired Electronics Engineer ).

I previously replaced the capitors on the mother board and front panel after they blew up.

And prevently (b4 it failed ) replaced the C2 on the hand controller, and after reassembly, the scope has tested out fine.

But I have 2 issues.

1 When I opened up the HC I failed to observe the white 2 pin connector and found it hanging loose. but observed 2 long pins which i assumed it was connected to was that correct?
2 Aditionally I had problems locating the ALT Led Diode in its slot and its now on all the time, it might have been like that before I started but I do not remember?

Therefore can you advise please.

- When should the ALT Led be out? and how an you locate it correctly?

- Should the 2 pins and the connector be  connected?
Thank you for you time.I have written to Mead but they have no details of the internal working of the HC.

Advice please.

Thanks

***(uk)


Edited by orionsbelt_UK, 23 September 2019 - 03:51 PM.


#15 jaymcgil19

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Posted 23 September 2019 - 06:56 PM

First, the ALT Led will be on when the ALT/AZ mode is selected.

 

Secondly, yes, that 2 pin connector goes on the 2 legs of the Led that is glued into the back of the pushbuttons to light them up. If the Led doesn't power up, switch the polarity.

 

John M


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#16 orionsbelt_UK

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Posted 24 September 2019 - 06:50 AM

Hi John
Thank you for your feedback.
I made an error its not the Alt Led (which now functions correctly after I switched the polarity ) but Led 8 East that seems to be continually on and I am unable to find an explanation for this in the manual. But the scope seems to function ok. So I must be missing something………………. Any answers please.
Additionally has anybody ever managed to produce a full ‘Menu Tree’ and is that published anywhere please. That would be a great help to understand how it all works
Thanks again
***(UK)


Edited by orionsbelt_UK, 24 September 2019 - 06:53 AM.


#17 rferrante

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Posted 24 September 2019 - 07:11 PM

Hi orionsbelt,

 

LED 8 is one of 4 backlighting LEDs. It is in series with LED 7 so for it to be "on" when LED 7 is not, there may be a short to ground somewhere on your board. It is not important for functionality. You can control the backlighting with the last "mode" of the handset top menu level. The menus are described in the manual, pretty completely, which you can find on-line if you do not have one. Try searching here on Cloudy Nights as well, someone should have posted a link to it at some time.

 

--Rob



#18 orionsbelt_UK

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Posted 26 September 2019 - 01:31 AM

Hi Rob

Thank you for your reply

***(UK)



#19 charletonp

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Posted 17 May 2020 - 07:48 AM

Hello.   An amazing thread and thanks to those who have taken the time to post the information !   I have tried to follow with some success on diagnosis as a (sad) classic LX200 12" owner in UK.

 

A few years back I had mounted the scope on a newly purchased equatorial mount and on power up a puff of smoke came out from behind the scope front panel and it was dead after that.    Tried the shop I bought it from who weren't interested (thanks for that).   Had the easily detached front panel looked at but I was advised it was ok and on inspection I see nothing obviously blown (especially looking a the tantalum capacitors  detailed on this thread).

 

Having decided the scope is a write off and with my son doing astronomy at university now, have decided I have nothing to lose by now looking further into it.   I followed the superb instructions on here to dismount the scope and went in underneath - taking off the bottom panel and eyeballing the main circuit board and the immediately visible drive electronics.   Closely inspected all capacitors and visible components and they all LOOK fine, no sign of burn on anything (and the images I've seen on here speak of readily visible damage).    Also now checked the hand controller unit just in case the smoke had come from that and I had mistaken it for coming out of the main front panel on the scope itself  - but nothing visible there either - all components looks shiny and as new !!   There is only 1 capacitor left not looked at - and that must be the dec board one - but I'm assuming that is housed in the forks and the smoke certainly didn't come from there.

 

Anyone got any ideas please ?   I could replace the capacitors anyway but I'm reluctant to do that on the basis "if it ain't broke don't fix it"  - though the one in the hand controller that destroys the ribbon cable may be worth doing !

 

And a question too if I may:  How you you know the polarity of the capacitor in place on the board to reproduce the same configuration in a replacement?  I think new capacitors have a short and long leg but these are cut to length on the ones already on the board so you don't know.

 

TIA guys.

 

Paul



#20 rferrante

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Posted 17 May 2020 - 11:54 AM

Paul,

 

The PCB has a small "plus" sign to denote the positive pin. You might not see it until you remove the existing cap. New electrolytic caps have a stripe on the case, that's the side for the negative terminal. The positive terminal lead is the longer of the two.

 

Since you had the "puff of smoke", look really carefully at the power panel PCB, the RA board, and the main CPU board in the base. One of them should have some kind of residue and/or smudge, which can guide you.

 

--Rob


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#21 charletonp

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Posted 17 May 2020 - 12:30 PM

Rob - thanks for that !   I have the power panel PCB inside with me (the scope is in the observatory shed) and I can see the +signs on the PCB there - so that helps a lot - cheers !    I have just looked at it with a magnifier and no damage visible so will go to the shed tomorrow and have a closer look at the other boards.

 

Paul,

 

The PCB has a small "plus" sign to denote the positive pin. You might not see it until you remove the existing cap. New electrolytic caps have a stripe on the case, that's the side for the negative terminal. The positive terminal lead is the longer of the two.

 

Since you had the "puff of smoke", look really carefully at the power panel PCB, the RA board, and the main CPU board in the base. One of them should have some kind of residue and/or smudge, which can guide you.

 

--Rob

 



#22 charletonp

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Posted 18 May 2020 - 05:19 AM

tn_gallery_331608_13305_1273275.jpg  This is the RA board as close in as I can get with it still mounted.   I'm not sure if the chip is showing some white residue but the C1 capacitor seems OK itself.




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