Jump to content


Photo

CG-5GT motor control failure, no response 17 & 16

  • Please log in to reply
25 replies to this topic

#1 Sean13

Sean13

    Mariner 2

  • -----
  • Posts: 205
  • Joined: 17 Nov 2012
  • Loc: North Platte, Nebraska

Posted 17 November 2012 - 09:23 PM

I am having some trouble with a CG-5GT mount that I bought used recently. It seems to work perfectly fine with its in the garage and warm, but as soon as its out in the cold I get no response 17 & 16 messages. I've tested any part I could remove in the cold, and all seem to perform just fine when cold. I've removed all the chinese glue/grease, and replaced it with good quality marine grease. There are no binding issues, all axis move freely. My power supply is brand new, and center pin has been spread with no help. The problem is very random. Sometimes it will work for hours just fine, and on a random slew it stops in the middle and gives me errors, sometimes it won't even get thru alignment. Its random as to what motor fails first, sometimes they both fail at the exact same time. Once one fails, the other isn't far behind.

After all I've done already I'm down to either the Motor control board or the power control board being the problem. Is this a common issue? I've read that the power switch is a big problem on the cg-5 and I should be powering it off by unplugging it instead. I have not been doing this, but will start. Could this have caused this problem?

#2 RTLR 12

RTLR 12

    Skylab

  • *****
  • Posts: 4498
  • Joined: 04 Dec 2008
  • Loc: The Great Pacific NorthWest

Posted 17 November 2012 - 09:40 PM

When you get both no response codes it is usually a connection problem between the HC and the MC board. You should look at the socket that the HC connect to the mount. Make sure the fine wire contacts are aligned correctly. With the mount turned on, wiggle the HC connection and see if you get a response. You could have a bad connection inside the HC or inside the mount where the Power board connects to the MC board. Also wiggle the full length of the coiled cable on the HC. There could also be a bad crimp on the RJ connector on the HC cable. I would not condemn the MC or Power boards yet.

Stan

#3 Sean13

Sean13

    Mariner 2

  • -----
  • Posts: 205
  • Joined: 17 Nov 2012
  • Loc: North Platte, Nebraska

Posted 18 November 2012 - 01:15 AM

Tried that lots of times with no response. Tonight it was a little warmer and it worked good for about 45 minutes, tracking jupiter perfectly. I was sitting there and herd a noise, like a computer makes powering down, an electronic whine or squeal, checked the scope and sure enough jupiter was drifting out of view, and touching either direction buttons gives a no response 16 and 17. Bring it back in the garage for an hour, works perfectly. Take it back outside, and within 20 minutes failures again.

Occasionally one motor will go out of control right before/while getting the error message. The only way to stop it is to shut it off. I've checked the board for bad connections and I notice there is a little browning on the wire insulation that rubs against the motor. Its not melted bad at all and no wire is showing, but I put some electrical tape over it anyway, but it didn't fix the problem.

#4 RTLR 12

RTLR 12

    Skylab

  • *****
  • Posts: 4498
  • Joined: 04 Dec 2008
  • Loc: The Great Pacific NorthWest

Posted 18 November 2012 - 07:08 AM

In the warmth of the day, put the MC board in the freezer and let it cool down for a while. Then quickly install it and see if this problem occurs. That will isolate the MC board to the cold and tell you if the problem lies with the board.

Stan

#5 Sean13

Sean13

    Mariner 2

  • -----
  • Posts: 205
  • Joined: 17 Nov 2012
  • Loc: North Platte, Nebraska

Posted 18 November 2012 - 11:49 AM

I will try that today, as thats exactly how I've been testing the other components like the hand controller and dec motor cable to see if they were affected. I will test the MC board like this today, however theres no guarantee the board is going to fail the second it gets cold. Sometimes it takes 45 minutes of being cold before the board truly gives out.

#6 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15357
  • Joined: 06 Jul 2007

Posted 18 November 2012 - 12:07 PM

When you get both no response codes it is usually a connection problem between the HC and the MC board. You should look at the socket that the HC connect to the mount. Make sure the fine wire contacts are aligned correctly. With the mount turned on, wiggle the HC connection and see if you get a response. You could have a bad connection inside the HC or inside the mount where the Power board connects to the MC board. Also wiggle the full length of the coiled cable on the HC. There could also be a bad crimp on the RJ connector on the HC cable. I would not condemn the MC or Power boards yet.

Stan


Yep. Check and clean all connections before fooling with the dadgum MCB! ;)

#7 Sean13

Sean13

    Mariner 2

  • -----
  • Posts: 205
  • Joined: 17 Nov 2012
  • Loc: North Platte, Nebraska

Posted 18 November 2012 - 01:52 PM

Checking and tightening all connections and wires were the very first thing I did the very first time I had any trouble. It doesn't matter how long I stretch, or how hard I push and pull, no wire or connection is causing this problem.

In fact the problem will manifest when no one is actually touching anything on the scope. It was tracking jupiter for over 30 minutes last night without a single touch of the hand controller and it failed when I was 10 feet away from the scope.

My next course of action was to completely clean and rebuild the mount, removing the Chinese glue. This made a giant improvement in the sound of the motors, they no longer whine and sound stressed. But atlas, it did not fix the problem.

#8 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15357
  • Joined: 06 Jul 2007

Posted 18 November 2012 - 02:28 PM

Stills sounds connection related to me. By "checking"...did you use a multimeter, exercising (moving/bending) the cables, and clean/recrimp the connections? Use zero residue cleaner ("tuner cleaner") or denatured alcohol. Grease will make absolutely no difference. This is almost certainly electronics/cable related. Pay particular attention to the HC cable... :gramps:

#9 Sean13

Sean13

    Mariner 2

  • -----
  • Posts: 205
  • Joined: 17 Nov 2012
  • Loc: North Platte, Nebraska

Posted 18 November 2012 - 03:01 PM

After removing the MCB from the freezer and reconnecting it as quickly as I could, the scope failed within 30 seconds of manual slewing. Was working fine before board went into freezer in the garage temperatures. I'm sure letting it warm up will result in it working fine again.

I have some pictures of the MCB and some things I found odd. The solder connections on the capacitors look hand soldered, and the weird powder looking residue on the opposite side of the capacitors, and a surface mount resistor I believe. Not really sure what happened here but it seems to be effected by temperature.

Think I might have any luck in resoldering the bad looking connections?

Attached Files



#10 Sean13

Sean13

    Mariner 2

  • -----
  • Posts: 205
  • Joined: 17 Nov 2012
  • Loc: North Platte, Nebraska

Posted 18 November 2012 - 03:02 PM

Other picture

Attached Files



#11 Sean13

Sean13

    Mariner 2

  • -----
  • Posts: 205
  • Joined: 17 Nov 2012
  • Loc: North Platte, Nebraska

Posted 18 November 2012 - 03:59 PM

Also, I checked continuity on the DEC power cable with a multimeter, wasn't much I could do for the hand controller unless I wanted to take it apart. I didn't clean them with any cleaners.

I did test the hand controller and the DEC power cable in the freezer about a week ago, and both performed just fine while ice cold and stiff.

#12 Phil Wheeler

Phil Wheeler

    Vanguard

  • -----
  • Posts: 2018
  • Joined: 31 Dec 2005
  • Loc: 3 miles WNW of Celestron

Posted 18 November 2012 - 06:00 PM

After removing the MCB from the freezer and reconnecting it as quickly as I could, the scope failed within 30 seconds of manual slewing. Was working fine before board went into freezer in the garage temperatures. I'm sure letting it warm up will result in it working fine again.

I have some pictures of the MCB and some things I found odd. The solder connections on the capacitors look hand soldered, and the weird powder looking residue on the opposite side of the capacitors, and a surface mount resistor I believe. Not really sure what happened here but it seems to be effected by temperature.

Think I might have any luck in resoldering the bad looking connections?


Sean, those look like the sort of solder joints which can cause problems because the solder didn't flow freely. The ones in the second image are better, but could be improved.

I'd get some good solder (some silver content) and a good -- not too warm, say like 700 deg -- soldering iron. Then remove the old solder with some wicking braid then flow new solder in so it does not bead up as the images show.

Phil

#13 Sean13

Sean13

    Mariner 2

  • -----
  • Posts: 205
  • Joined: 17 Nov 2012
  • Loc: North Platte, Nebraska

Posted 18 November 2012 - 06:37 PM

My only soldering tool is a pretty powerful gun, I don't have an actual iron because well I hate them. I have done some PCB soldering with it before, but come to think of it the part I tried fixing didn't actually work in the end, so I hope the solder gun isn't to blame.

I suppose my only option if its bad is to buy a new board, so I really have nothing to lose if I mess it up or it doesn't fix the problem.

#14 Sean13

Sean13

    Mariner 2

  • -----
  • Posts: 205
  • Joined: 17 Nov 2012
  • Loc: North Platte, Nebraska

Posted 18 November 2012 - 07:17 PM

I stand corrected, I found a 100 watt iron around the house. My only solder here appears to be a Tin/Lead alloy. I will run to the store and see if I can find something of higher quality with silver to use on it.

#15 Sean13

Sean13

    Mariner 2

  • -----
  • Posts: 205
  • Joined: 17 Nov 2012
  • Loc: North Platte, Nebraska

Posted 18 November 2012 - 10:38 PM

Couldn't find any better quality solder locally on a Sunday night, so I used what I had. Desoldered with a braid and applied a fresh drop to each of the 6 connections. Fired up fine and has been working in the garage for about 30 minutes now. Going to haul it outside and see if it solved the temperature issue.

#16 Sean13

Sean13

    Mariner 2

  • -----
  • Posts: 205
  • Joined: 17 Nov 2012
  • Loc: North Platte, Nebraska

Posted 19 November 2012 - 12:11 AM

And no difference, still fails as soon as it gets cold. Looks like its time for a new board. :(

#17 EdTheEdge

EdTheEdge

    Surveyor 1

  • -----
  • Posts: 1570
  • Joined: 10 Apr 2009
  • Loc: Lomita, CA

Posted 19 November 2012 - 11:14 AM

You had my hopes up! Too bad resoldering didn't work. :(

#18 Sean13

Sean13

    Mariner 2

  • -----
  • Posts: 205
  • Joined: 17 Nov 2012
  • Loc: North Platte, Nebraska

Posted 19 November 2012 - 01:33 PM

Yea I was pretty excited thinking it was going to work too. Ordered a new board this morning so hopefully I should be up and going again soon.

#19 blave

blave

    Lift Off

  • *****
  • Posts: 19
  • Joined: 11 Aug 2009

Posted 27 November 2012 - 02:33 PM

I have had exactly the same problem with my AS-GT pretty much since I got it - intermittent 16 and 17 errors (not always at the same time though). I've spent a lot of time trying to determine what is causing it, but I have to say you've been a lot more thorough than I have been. To make a long story short, I've decided that my next step would be to replace the motor board. However, the fellow that I bought the mount from is willing to buy it back knowing about these issues, so I'm not going to mess with it anymore... My iEQ45 is on order 8^) .

good luck,

Dave.

#20 Sean13

Sean13

    Mariner 2

  • -----
  • Posts: 205
  • Joined: 17 Nov 2012
  • Loc: North Platte, Nebraska

Posted 29 November 2012 - 01:53 PM

New Motor control board arrived yesterday. Got it installed and fired up, scope works fantastic now. Was out for about 4 hours last night and not a single error.

During the first alignment I did have a hiccup, it seemed like the computer thought the scope moved more then it did and it completely screwed up my first alignment. I read that the motors on this mount have an optical sensor that keeps them in sync with the computer. I'm guessing there was an error reading the sensor and the mount thought it was off and tried to correct itself. This only happened once, and perhaps its because I had just moved it outside from the garage, and has some dew issues on the lens on the optical sensor? Just a guess, but thats really what it felt like. Waited 20 minutes and aligned it again, no errors the rest of the night.

Looks like its fixed and working good. Very happy with the scope and mount now. Thanks for the help guys!

#21 Phil Wheeler

Phil Wheeler

    Vanguard

  • -----
  • Posts: 2018
  • Joined: 31 Dec 2005
  • Loc: 3 miles WNW of Celestron

Posted 29 November 2012 - 05:20 PM

Great to hear that, Sean. Sometimes problems like this are less easily corrected!

#22 ohioalfa64

ohioalfa64

    Mariner 2

  • -----
  • Posts: 200
  • Joined: 16 Aug 2012
  • Loc: Ohio (NW)

Posted 29 November 2012 - 09:14 PM

Sean13,
What is the motor board part number and what did it cost? Did you buy it from a third party or manufacturer. Finally, how painful was the disassembly and reassembly process? I feel you have discovered the secret of life for all used CG-5 GoTo mounts. Please share this info.

#23 Sean13

Sean13

    Mariner 2

  • -----
  • Posts: 205
  • Joined: 17 Nov 2012
  • Loc: North Platte, Nebraska

Posted 29 November 2012 - 10:51 PM

This was the part I ordered directly from Celestron:
http://www.celestron...or-board-3.html

Cost was about $115 with shipping, and installation was fairly simple.

Actual disassembly of the mount, removal of the Chinese glue, re grease and reassemble was not so simple. The worm gears will take some time and effort to set the mesh just right to achieve as little slop as possible. Takes some trial and error but is rewarding with very responsive slewing. The mount can be further programed to compensate for any slop you may still have, I ended up having almost none. The motors were much much quieter with the new grease.

#24 mclewis1

mclewis1

    Thread Killer

  • *****
  • Posts: 10737
  • Joined: 25 Feb 2006
  • Loc: New Brunswick, Canada

Posted 29 November 2012 - 11:54 PM

I feel you have discovered the secret of life for all used CG-5 GoTo mounts. Please share this info.

MC board failure is actually exceedingly rare. Problems like the OP experienced are much more likely to be a) power B) connectors c) firmware

#25 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15357
  • Joined: 06 Jul 2007

Posted 30 November 2012 - 07:42 AM

Yep, with the first two being the cause of the overwhelming majority of problems. ;)






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics