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Hello Astronomers,

I have some sad news, sad for me anyway, but unfortunately during the final night of imaging my last DSO, the Fighting Dragons in Ara, my CGEM blew up.

At about 4 am, I went outside to check on the imaging progress and decided to dim the laptop screen but accidentally hit the "sleep" button instead of the "DIM" button. Usually this shouldn't be a problem.... but when I "woke" the computer up, the CGEM stopped tracking. Not thinking like it's a big deal, I tried to re-center the object and guide star and this is when I realized that there is something seriously wrong as the mount was not responding to my computer or hand controller commands.

When I power cycled the mount and hit a RA button, the mount moved, it moved at full speed until the OTA and camera almost hit the peir.... the only way to stop it was to cut power to the mount.

Power cycling it a few times did not change anything except that the mount stopped responding in RA completely.... note that the DEC function works as normal.

The hand controller is working normally and not reporting any NO RESPONSE error messages either.

I went on a fault finding mission and tried a different Hand controller with no change than I opened the CGEM and swapped the RA and DEC motors on the main motor control PCB to determine whether I burned out the motor.

With the motor connectors swapped the mount moved in the RA axis and worked properly by pressing the DEC buttons but now the mount is not moving in DEC, so I knew that the motor is not burned out, but the Motor Control board is faulty, possibly the RA encoder/controller chip.

I tried to re-flash the MC Board firmware, hoping that it's possibly just a corrupted data in the EPROM, but after a successful firmware flash, that did not change the situation.

With is information, I need to get a replacement motor control board, and this might take a while to arrive from the USA... so until that moment I will have to return good old observational astronomy using my 14" Dob and imaging will have to wait for the future.

I guess I'm lucky in a way that the failure happened toward the end of imaging my last image, in that last hours, instead of in the middle of it, so at least I ended up with an image.

 

My theory why this has happened:

I don't think that accidentally sleeping the laptop caused the mount to fail, at least not the act itself... of course, there is a possibility that it's just long term use and eventually everything fails, since I had the mount for 9 years, and it did do a lot of tracking hours... BUT than again it did work flawlessly for all of this time until soon after I started experimenting with PEC, and I had PEC running when this happened.

Could it be that PEC in the mount was trying to move the RA axis in one way, and PHD2/GPUSB tried to move the mount in the opposite way, causing some kind of conflict, or short circuit like/excessive current drain event? perhaps not in general use with quick pulse commands, but when I did sleep the laptop, could it be that GPUSB was stuck in nudging the mount in one direction, and than PEC tried to move it in the opposite direction and that state was held for long enough to burn out the encoder or controller IC?

Either way, comparing PEC programmed mount on PHD2 guiding accuracy to no PEC accuracy, the results are so close that PEC might not even be worth the hassle, and PEC is more useful for unguided imaging?

I think that when I fix my CGEM, I might stick to NON PEC autoguiding since, like I found, PEC is no, or very little, improvement, such a small improvement that the reason can be caused by just the atmosphere becoming slightly more still within the comparison time... accuracy difference of only 0.02-0.05" arc sec RMS.

 

Thanks for reading and of course thoughts, opinions and experiences welcome.

 

Clear skies,

MG  

 

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UPDATE: New MC Board is in.. the CGEM is working... CGEM Resurrection... 

 

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Hiya

It was most likely a voltage spike that killed the board - probably when you power cycled. Maybe have a look at the old board, especially the input circuitry to look for any obvious damage.

Louise

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13 minutes ago, Thalestris24 said:

Hiya

It was most likely a voltage spike that killed the board - probably when you power cycled. Maybe have a look at the old board, especially the input circuitry to look for any obvious damage.

Louise

Hello Lousie,

There's absolutely no signs of damage on the board... I inspected it thoroughly looking for an obvious burn such as a bulging cap or charred components or dry joints to attempt a repair but everything looked clean...

Hopefully this board will last as long as the last one.... now to my next step.. the Obsy computer..... my SFF PC and LCD arrived and I need to port my recently failed laptop OS to it with my setup, than I'll be back in action.... I opted to get a mini desktop PC instead of another laptop for the obsy... losing 2 laptops in the scope hut and both within 18 month, I figure that a desktop might be a bit tougher for the elements.

 

 

Edited by MarsG76
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If the damage is done to an IC, you will not see any burns or scars... and very little is needed to kill them.
anyway, I am glad you are in bussiness again!

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Just now, Waldemar said:

If the damage is done to an IC, you will not see any burns or scars... and very little is needed to kill them.
anyway, I am glad you are in bussiness again!

As it looks like it was the IC after all, but I was hopeful that it was a simple fault, but I got quite a few years out of it.

 

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I am not familiar with your mount, but if the IC is in a socket, you can replace it and have a spare board at hand...
If you do so, ground yourself while replacing it, because static electricity is a real killer for integrated circuits.

Edited by Waldemar
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2 hours ago, Waldemar said:

I am not familiar with your mount, but if the IC is in a socket, you can replace it and have a sparte board at hand...
If you do so, ground yourself while replacing it, because static electricity is a real killer for integrated circuits.

I play with electronics for a living ;-).. but unfortunately the RA encoder chip is surface mounted... still replaceable if I could get my hands on the IC...

 

Edited by MarsG76
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Yes all surface mounted stuff is modifiable. Although one time we did that at work to make a special dimm and the PCB got so soft it was like a fruit roll up :)

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Glad you got it sorted and have the skills to do so.  If it happened to me I would just have to replace the mount unless I happened to encounter some-one clever enough and kind enough to repair it for me, I have no electronics skills at all.  

Carole 

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On 10/06/2019 at 00:58, carastro said:

Glad you got it sorted and have the skills to do so.  If it happened to me I would just have to replace the mount unless I happened to encounter some-one clever enough and kind enough to repair it for me, I have no electronics skills at all.  

Carole 

I'm very sure that if it happened to you and you dropped a line on here, someone in the area would be more than happy to help... I know that if someone down here near me was in that predicament, I'd be more than happy to give a helping hand.

 

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On 09/06/2019 at 04:34, MarsG76 said:

As it looks like it was the IC after all, but I was hopeful that it was a simple fault, but I got quite a few years out of it.

 

My CGEM II died as well. Pretty sure it's the board. Question: what is an IC?

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6 minutes ago, Michael Milligan said:

Question: what is an IC?

"Integrated Circuit".  Usually a rectangular blob of plastic with metal "legs" sticking out that contains lots of electronic components in a single package.

James

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Replacing the board is probably the best option. Apart from the issue of replacing surface mounted components, finding out which one is at fault can be a real problem, if you do not have the precise schematic of the board. As a rule of thumb, it is often, but not always the power components that burn out before anything else (and in that case damage may well be detectable, visually or by smell), but any active component can suddenly give up the ghost without any outward sign of problems. It is also quite likely that some components are so-called ASICs (application specific integrated circuits) custom made for this application, and therefore hard to source. Replacing the board is the safest and quite likely most cost-effective option.

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Thank you James and Michael. I was hoping it was repairable because it's $314. I get the  "No Response 16" and "No Response 17" errors.

The weird thing is Celestron tech support people never thought of the problem being the main board. In fact, after they replaced my new StarSense which, of course, didn't work either, they still wanted me to try hooking my StarSense hand contoller to the StarSense camera, then a cable from the camera to the hand controller port. They never mentioned the main board. I just googled and found it.

My telescope is an A-P EDT 130. The image sharpness and detail are indescribable. Now I fear I'm stuck with a less than adequate mount for astrophotography purposes.

I'll bite the bullet and replace it and hope it doesn't happen again.

Thanks again.

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     0

Thank you James and Michael. I was hoping it was repairable because it's $314. I get the  "No Response 16" and "No Response 17" errors.

As I understand it no response 16 and 17 errors are power issues...if doubt it's the board.. how are you powering? Mains or battery? And it might be worth looking at the power to board connector first..

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15 hours ago, Michael Milligan said:

Thank you James and Michael. I was hoping it was repairable because it's $314. I get the  "No Response 16" and "No Response 17" errors.

The weird thing is Celestron tech support people never thought of the problem being the main board. In fact, after they replaced my new StarSense which, of course, didn't work either, they still wanted me to try hooking my StarSense hand contoller to the StarSense camera, then a cable from the camera to the hand controller port. They never mentioned the main board. I just googled and found it.

My telescope is an A-P EDT 130. The image sharpness and detail are indescribable. Now I fear I'm stuck with a less than adequate mount for astrophotography purposes.

I'll bite the bullet and replace it and hope it doesn't happen again.

Thanks again.

Hi Michael,

Before you deem your main PCB to be the culprit, I recommend you disconnect all accessories, like the StarSense, from the mount and try a different power supply. If you mount works at any stage before failing than it's not your PCB, and also it if works with accessories disconnected than again its not your PCB that's at fault.. but if you determine that the main PCB is faulty than it's not too expensive to fix.... I got my replacement board for $250... so not the end of the world kind of expensive... working fine until today... and the PCB in the CGEM II is (most likely) the same as in the original CGEM....

I'm surprised at Celestron tech support, they should have told you to first disconnect the Starsense and test the mount.... 

 

 

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{Hi just read this page

My Celestron Advanced cg-5  gt mount has now developed a no response 17 or 16 error  (do not know why)

can any body suggest where I can get a replacement  printed circuit board asap

Tried a couple of Celestron Dealers here in the uk bust no answer  to date.

Beginning to get withdrawal systems

Thanks regards

 

 

 

 

 

Edited by todick
miss spelt
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2 hours ago, todick said:

{Hi just read this page

My Celestron Advanced cg-5  gt mount has now developed a no response 17 or 16 error  (do not know why)

can any body suggest where I can get a replacement  printed circuit board asap

Tried a couple of Celestron Dealers here in the uk bust no answer  to date.

Beginning to get withdrawal systems

Thanks regards

 

 

 

 

 

I got my replacement board from BinTel in Sydney, you can call/email them and see if they'll post overseas otherwise contact OPTCorp (OPTCorp.com) in USA, I got a lot of stuff from them and they're great, definitely ship overseas.

 

Edited by MarsG76
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