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CGE misbehaving

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#1 jpmills

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Posted 05 March 2013 - 11:35 AM

I was just wondering if anyone who has (or had) a CGE mount has had the problem of the mount suddenly acting weird. Alignment would go just fine, including 2-3 calibration stars. Go-to would function correctly for a while then all of a sudden it couldn't find anything, take the wrong direction around the tripod, etc... The mount is currently carrying a C14, which when it works, works really well. This is used primarily as a traveling scope for a University. Clearing the settings back to factory defaults seem to cure it but it doesn't last.

Any thoughts?

Thanks,
Jon

#2 corpusse

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Posted 05 March 2013 - 11:44 AM

Mine is like this now. Does it sound different too? I will eventually get the Bennett cable upgrade which should solve the problem. I actually can do 2 star align but if I try for any calibration stars it will start to go crazy.

I'm currently only using the mount for planetary and the planets are some of the few objects I can find even if the go to is messed so I'm just dealing with it.

#3 mclewis1

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Posted 05 March 2013 - 07:49 PM

1) Power problems - try a different power source. Low power can show up as a whole variety of strange problems before you get the more common HC resets and NR errors. Power supplies and batteries can sometimes start to fail without showing obvious problems.
2) RA/DEC cabling issues - try different cables but also plan to do the Gary Bennett upgrade.
3) Limit switches need adjustment - these will cause all sorts of strange issues. They are quite easy to adjust, the best guidance for this is on the Yahoo CGE_uncensored group.
4) Internal connector issues - It can be useful to just carefully go over all the internal connectors. Remove and replace each one in turn, and check for poor connections with each wire.

#4 jbalsam

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Posted 14 March 2013 - 11:26 AM

+1 to what mclewis1 said. Check your power situation first. I have a CGE, and when I first got it I wasted several nights trying to do alignments that continually failed at different points. I was using a 12V power supply, but it was only rated to about 0.75A. I switched to a 12V/3A supply and it's been fine ever since.

#5 herrindude

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Posted 14 March 2013 - 08:10 PM

DO the Gary Bennett mod and loose the problems, sure its expensive, but you will never have problems again. I did it an have never regretted it.

#6 EFT

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Posted 15 March 2013 - 10:19 AM

I agree that the number 1 likely problem is the power supply. A 3A minimum power supply is the best and if you are using a battery, then you need to have it checked out to see if it is still good. The other possibilities usually exhibit much more significant problems like "No Responce 16/17" or simply not working from the start. From there is is going to be connector issues with the RA and/or DEC cables.

#7 Eddgie

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Posted 15 March 2013 - 03:43 PM

I have been running a CGE for many year now.

Replacing the cables is not really cost effective and usually not necessary.

This is my opinion and my opinion only.

All of the Celstron mounts and the Meade LXD mounts I have owned have all mis-behaved over the years.

I replaced the cables on the CGE, and it did not really truly "Fix" the problem.

You can spend a lot of time and money on an upgraded cable system, but there is no need two.

The first thing that I have found will resolve the problem is to clean the sockets that the cables plug in to.

I believe that these contacts get either oxidation (they are supposed to be gold plated, to prevent this, but I doubt that anyone does this anymore, or loose tension.

Use DeoxIT and spray the contacts liberally.

These plugs are "Self Wiping" which means that as you plug and unplug them, the friction of one against the other is supposed to clean them, but if you don't remove and replace them regularly, I think the simply oxidize out.

About once every year, my mount will start over-driving in Dec. This is the main symptom I get that the software has corrupted. I have to do a hard reset to fix it, but if I don't clean the contacts, it will just come back.

Cleaning the contacts and in runs fine for another year (I never remove the cables when I take the head in or out, so no wiping takes place).

Once (after many years of ownership) cleaing the cables did not work. I removed the plate in top of the semi Pier and reseated every cable multiple times to wipe them. I put a new battery in at the same time. Mount worked fine after that but it has been about a year ago, so contact cleaning is almost due.

My mount will sit outdoors under a plastic cover for weeks at a time, so I am sure the exposure quickens the oxidation.

Replacing the cables can be a "Temporary" fix, because just replacing the cable will give the contact one "Wipe" and this may clean it well enough to buy you some time.

Someone said that the problem was grounding. I bonded the shells of the cables to the plugs and this did noting to resolve the problem, so I don't think that it is at all related to the failures people experience.

So, swapping the cables may "appear" to fix the problem, but it kept coming back for me.

But now, when it happens, I shoot some DeoxIT into the sockets and on to the ends of the cables and plug-unplug a half dozen times to wipe them, and away I go.

For about another year anyway.

So for me, the cables were not really a fix at all. Cleaning the cable sockets on the mount always gets me back into operation.

I had an LXD thought that kept failing. No amount of cleaing would fix it.

For this mount, I had to use a tiny spring hook and dig under the contacts on the plug on the mount that the HC plugged in to. I used this tiny spring hook (actually a tiny little crochet hook I believe) to re-arch the contacts in the plug. Fixed it.

Good luck with whatever path you take but if you clean the contacts and re-set the HC, my bet is that it will hum along fine for another year or two.

#8 Alph

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Posted 15 March 2013 - 05:24 PM

Replacing the cables is not really cost effective and usually not necessary.


That's right! It makes no sense. There is a very simple and very effective method to fix CGE cable problems. I am just amazed to see so many CGE owners who bought those super expensive replacement cables. It is just mind boggling to spend 25% to 30% of the mount value on cables!

#9 RStar

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Posted 15 March 2013 - 07:12 PM

If you're reasonably handy you can do the Bennett mod yourself at a fraction of the cost. Best thing I ever did for my CGE. Two and a half years of dead on goto's and flawless guiding, 40 to 50 imaging nights per year.

http://www.pbase.com...upgrade_project

Bob

#10 PhilCo126

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Posted 30 May 2013 - 03:06 PM

In Bob's weblink: click AstroImaging... click Equipment ... to get to the excellent photo report of modifying the Celestron CGE with Gary Bennett's CGE cable replacement kits.

Thanks for sharing :bow:

Looks like Gary Bennett made other TPI - Telescope Performance Improvements: http://www.bendun.net/


#11 Frank

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Posted 02 June 2013 - 09:36 AM

I've installed the Gary Bennet Cable replacement set at my CGE. This sorted a lot of DEC runaway problems, but not all. I found out that low temperatures (5 degrees Celcius or lower) make the cables stiff, resulting in problems with the connectors. I finally replaced the cables themselves by low-temperature ones (suitable for -30 degrees Celsius in a moving setup) and relocated the connectors and this finally sorted all issues. I'm actually running the modified layout since 1.5 years, and all is still fine.

Edit: truly important: try to avoid cables pushing against eachother; in my setup, this happened whith the OTA at the western side of the mount, just before meredian flip. I installed a 90 degrees connector at the RA cable and modified cable length to eliminate this.

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#12 Frank

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Posted 02 June 2013 - 09:37 AM

Picture 2

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#13 Frank

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Posted 02 June 2013 - 09:37 AM

Picture 3

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#14 David Pavlich

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Posted 02 June 2013 - 10:17 AM

The problem with the stock cables is that they are very stiff. Eventually, the Dec. socket becomes "wollered out" for lack of a better term. In other words, the cable doesn't make good contact in the socket. I tried all of the fixes, cleaning and Marty cables, but ultimately, I ended up having to replace the socket/board. From that point, I used Marty cables and never had a problem again.

The secret is to get those stiff, stock cables, especially the Dec. cable, and replace them with Marty cables.

David

#15 Frank

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Posted 02 June 2013 - 01:26 PM

OK, but the cables Gary Bennet uses is also too stiff, in cold weather.

#16 gfeulner

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Posted 02 June 2013 - 01:54 PM

Jon- I've had this problem with my CGE. It's probably loose cables not making proper contact. I found that I could almost completely eliminate the problem by attaching plastic ties to the cables and attaching the ties to the body of the mount leaving slack for movement when the mount is slewing. If you join the CGE Yahoo group there are a lot of discussions about this recurring problem. Celestron didn't do their homework when they designed this mount and could have saved their customers a lot of grief if they were more careful. Gerry

#17 David Pavlich

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Posted 02 June 2013 - 04:53 PM

OK, but the cables Gary Bennet uses is also too stiff, in cold weather.


True, however, the modification eliminates the cable/socket combination and goes from that weak point to a soldered connection.

David

#18 frito

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Posted 02 June 2013 - 06:59 PM

i was going to say check cable connections. i don't have any experience with the CGE but i have a CG-5 AS-GT and two nights ago i had the dreaded power pin problem on mine and it was not the center pin, it was the negative outer leaf connection, i took the electronics out of the mount head and managed to bend the leaf out so it made good connection again and put it back together and all was well that night.

enter last night, i'm out at a dark site for my club doing outreach, got my mount all set up go to power it on and out of nowhere it goes and slews in RA for no reason. i'm like *BLEEP* what did i mess up when i put it back together. so after consulting with others there that have owned CG-5's and they are dumbfounded by it i go well it does stop slewing after a short while and it appears to slew to alignment stars correctly so i guess when it gets dark enough i'll just try to align it and see what happens right?

well needless to say it slewed to the first star very well as it should but then i go to center said star and every time i pressed the down arrow rather than turning in dec like it should all of a sudden it turns in RA at a rapid pace and then stars studdering and then stops. i'm like great somethings up big time here.

next i tried a factory rest. nope nothing still does it. then i tried reloading the HC firmware after finding that if i started it into programming mode it did not slew on power up like it was doing with normal power ups. nope another 10 min wasted.

finally i decided i should crack it open before it gets too dark and investigate. what do i discover? yep the RA motor ribbon cable was not seated fully into the MC board so i pushed it all the way in and powered it up while holding the electronics off the mount so it won't short and voila problem solved.

bad connections to the motors can clearly cause celestron mounts (and likely most all other brand mounts) to do all kinds of crazy things probably because they are not getting the proper signal back from the encoder in the motors is my guess.

#19 payner

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Posted 09 June 2013 - 11:57 AM

David: Do you know of a source for "Marty cables?"

Best,
Randy

#20 mclewis1

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Posted 09 June 2013 - 01:12 PM

LPI

http://www.vpi.us/cable-sf-shld.html

#21 jrbarnett

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Posted 10 June 2013 - 10:31 AM

Yep. Stiff cables, a weak, poorly supported junction with the PCB in the pier and a less than ideally secure socket junction/type, are the bane of these mounts. I think that if you observe in very cold climates, these probably aren't the mounts for you even with a cable swap, whether Marty cables or the Bennett mod.

I presently use Marty cables but most of my observing is done in moderate to warm weather. I use a different mount on very cold nights. Thus far, they have worked for me. But I do have the Bennett kit on the shelf for if and when the Marty solution no longer works for me. I'm also considering either picking up a low mileage "donor" CGE or a full set of replacement components from Celestron, or both. I do like the mount, and it's a shame that Synta cheaped out on the QC improvement cycles over the life of the design. It has brilliantly decent quality components, with a few pieces of junky compnents/casting and a couple of glaringly poor engineering design bits. This could have been a glorious mount that would have rendered Losmandy irrelevant prevented the slew of flaky Synta/Celestron mounts that followed, and provided users with a truly made in USA option with up to date, non buggy (*cough* Gemini II *cough*) electronics and software. But no. Penny wise and pound foolish won the day. The bronze gears in the CGE alone are worth more than all of the pot meal used in the CGE Pro combined. :grin:

I picked up a good condition AP900 QMD last week that I am cleaning and restoring. It will be revamped tested for a few weeks and then...go on the shelf for the day when my CGE can no longer be easily massaged back into working shape (or I get an observatory property, whichever comes first).

The key to any successful mission is redundancy of essential systems. :grin:

Regards,

Jim

#22 mclewis1

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Posted 10 June 2013 - 12:56 PM

Jim,

I'm with you on the general comments ... but I don't think there's much of any cold weather issues with Gary's cable upgrade. My CGE has been bullet proof over two winters since I did Gary's drill less cable upgrade (mount is in a POD). It was also pretty darn good using the Marty cables over the previous winters, one here in Canada and two more in Colorado (always stored in unheated garages). I upgraded to the Marty cables shortly after getting the mount ... even before I had any issues.

I don't think I've heard of any cold weather specific issues with Gary's upgrade from anyone else either. I guess it's possible, but with the connectors being threaded together and the lack of pulling on the boards most of the potential issues have been addressed. It would be cool if Gary B used a high silicone content cable to keep it more flexible in the serious cold ... but I don't know what the cost/benefit trade off might be for that type of change.

I'm not sure how many CGEs are operational here in the great white north but I don't hear about many folks complaining about cold weather issues with the few I know about (all have Gary's cable upgrade).

#23 EddWen

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Posted 10 June 2013 - 01:08 PM

On the other hand, speaking not in general, but specifically about the one I own; over the last 10 years, I've only had one minor glitch with my CGE. One of the limit switches did not switch cleanly, which confused the control board. Fixed with a replacement switch from Radio Shack.

It has had no modifications. It has carried a variety of scopes and performed well. It has also endured hot and cold conditions including this one. After the snow and ice melted, it worked, and still does work fine.

I recently sold an A-P 900QMD (not to Jim) due to lack of use.

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#24 payner

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Posted 10 June 2013 - 06:41 PM

Hi Mark and thanks for the link. I've had no issues with the stock cables, but can see the benefit of replacing with more flexible ones that will place less stress on the receptacles.

Best,
Randy

#25 CounterWeight

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Posted 11 June 2013 - 09:58 AM

During the time I owned the CGE the issues I experienced were either from the cables or the home/limit switches without exception. Working on it and replacing parts was really quite easy. I agree with Jim about the mount and missing the boat. When it worked, it worked like a champ. Watching it 'whirl-o-matic' with my TEC160 just wore on my nerves too much.






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