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CGE HELP!!!!

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#1 tjensen

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Posted 16 August 2012 - 10:36 PM

The first beautiful night we've had in months... no clouds, no storms, low humidity, good seeing... turn on the scope and start a 2 star alignment (showing a friend how it all works too of course)... I'm focusing Arcturus when all of a sudden the scope goes into a runaway RA slew. Power down, start over, and one of the RA direction buttons is dead. Change cable and the RA works and the Dec has a dead button.

SO... the million dollar question... is it the hand controller or the main board? I know I have a bad RA limit switch, I've been putting off changing that for months. Hasn't been an issue with the weather we've been having.

Anyone have an idea how to diagnose the problem? Short of ordering a new hand controller?

Oh, did I mention I ordered a hyperstar for the scope. It's supposed to arrive on Tuesday.

Naturally.

Desperately
Tim

#2 MDearingJaxFL

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Posted 16 August 2012 - 10:49 PM

When you changed the cable was that to mean you swapped the external RA and DEC cables or the HC cable? Also, did the mount successfully go through the switch position calibration
before the data section?

:>) mark

#3 tjensen

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Posted 16 August 2012 - 10:52 PM

Hey Mark,
I switched the external RA and Dec cables. No, I haven't gone thru a successful switch position calibration my last several times out. I think I have a bad one that needs replacing. I've been meaning to look at it, but just bypassing the switch check has been working.

Tim

#4 MDearingJaxFL

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Posted 16 August 2012 - 11:31 PM

Start off conservatively; clean the ends of the questionable
cable and see if that gets both axis working.Corrosion on the contacts can cause allot of problems sometimes. There can be a grounding short in the cable too.

Before, once you powered back up did you get any more runaways in either axis? No might be a good answer.

If you can get both axis working either by swapping the good cable of getting both cables to work or replace one, that would seem to indicate that your HC is fine.

:>) mark

#5 tjensen

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Posted 17 August 2012 - 08:36 AM

Yeah... could be the cable. I've had issues with those before. I thought I'd fixed that with some 90* ones. Guess it's time to fork out for the Bendun upgrade.
Cheers
Tim

#6 mclewis1

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Posted 17 August 2012 - 09:40 AM

Tim, This is unfortunately a not too uncommon occurrence with mounts that have not been used for a while.

The RA/DEC cables are standard Ethernet patch cables ... with a twist. They also require conductive shells that are tied together. So the common regular plastic connector RJ45 patch cables will not work.

Gary Bennett's cable upgrade is indeed the best permanent fix for the problem. If however you want to try a less expensive solution (and not usually permanent in the long term) you can order the VPI "Marty" cables ... http://www.vpi.us/cable-sf-shld.html (these are good quality flexible cables that are also really inexpensive).

Be aware though that it may not be the actual cables, corrosion in the sockets and sometimes the solder connections themselves can become a problem over time. If the sockets have started to degrade (from the cables being flexed back and forth over the years) then the VPI cable upgrade won't fix the problem (and you'll probably be back to the Gary Bennett upgrade).

I'd get that limit switch replaced and upgrade the cables. As Mark suggested cleaning the contacts is also a good idea. Get an aerosol can of contact cleaner and also use a Qtip to "scrub" the little connections a bit (being careful not leave any threads and debris from the Qtip in the socket). I'd also take the opportunity to go through all the other internal and external (HC) connections in the electronics base and the external 12v power connections (power connector, split the pin a bit, etc.).

#7 tjensen

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Posted 17 August 2012 - 10:47 AM

Hey Mark.
Thanks for the advice.
I've been the Marty Cable route already. Nothing seems to last. Might mean the sockets are going bad. Since this has been a headache since I got the mount, I think I'll bite the bullet and get Gary's kit.
In the mean time, I'll take the offered advice and clean the contacts and such. It's supposed to start raining here tonight and last for at least 4 days, so I guess it's a good time for an overhaul.

Thanks to all for answering. I was feeling pretty desperate last night!.
Cheers
Tim

#8 Tim Gilliland

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Posted 17 August 2012 - 01:33 PM

Sounds exactly like mine until I installed the Gary Bennet cables in Febuary. They are a bit pricey but a sure solution to cable problems which plague the CGE. I had Marty cables but they didnt last.

#9 MDearingJaxFL

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Posted 17 August 2012 - 08:41 PM

Understand your frustration; I had the CGE blues earlier this year.

The RA/DEC socket board is inexpensive.

If you decide to go into the pier to check all of the connections as Tim G. suggested, just examine the motor control board that is attached by a small screw or two to the top plate in the pier; looking at the board I believe the upper two chips on the left are usually the ones that blow. You can tell if they are blown by looking for a bubbled or melted spot near the center of each chip.
Hopefully that will not be the case.

Pardon if this is redundant, but it is wise to wear a grounding wrist strap and work atop a static dissipation pad (available as a kit from Radio Shack)before you touch anything inside the pier.
:>) mark

#10 David Pavlich

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Posted 17 August 2012 - 09:02 PM

Hey Tim... Here's a sort of tutorial I did about the Dec board.

David

#11 tjensen

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Posted 19 August 2012 - 04:10 PM

OK, I've cleaned the contacts and changed the RA limit switches. Everything seems to be working again. I'm still going to do the cable mod. Gary said he get it out to me at the end of the week. Sohopefully that will go well and that will be the end of the cable issues.

I want to thank everyone that responded to my post. I was a bit freaked out that night and it's nice to know there are folks out there one can rely on for support.

Cheers
Tim

#12 David Pavlich

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Posted 19 August 2012 - 09:23 PM

No problem, Tim. I take Paypal. :roflmao:

David

#13 MDearingJaxFL

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Posted 19 August 2012 - 09:27 PM

Tim,

always glad to help........

:>) mark

#14 Bowmoreman

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Posted 20 August 2012 - 12:00 PM

Glad to hear your reasonably back on track, Tim!

I suspect that it was the sockets getting grunged up; likely due to your rather humid environment - at least contrasted with mine! :lol:

I was lucky with my CGE, the Marty cables alone "did it" for me; never needed the full Gary Bennett kit / approach...

'Course, I only went another year or so before I bit the bullet and bought the MI250, selling the CGE... the good news is I got 2.5 years out of a CGE purchased used for $2100, selling it for $1850... not too shabby...

I still miss some things about that mount, mainly NexStar! It's a good platform, worthy of investment to keep it running in top notch form!






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