G11/Gemini slewing problem. Any thoughts?

[1ponders] (Paul) · #1 15-02-2009, 07:36 PM

We are having a problem with the G11 at the Mapleton Observatory. The RA keeps stalling and displaying "Motor Stalled" or "Tracking Stopped".

I did all the normal things, checked balance, checked worm alignment and mesh, even loosened it right off. I then swapped the dec motor with the RA motor, and drove the Dec motor same problem. RA (dec motor) kept stalling. Then put the RA motor back on the RA cable and ran the RA motor unconnected to the mount, "Tracking Stopped". Ah Ha I thought, the motor is stuffed. But no! I connected the Dec motor (again not connected to the scope)...."Tracking Stopped", "Motor Stalled" and then connected the Dec cable....np, the motor ran fine.

So how can both motors run fine when connected to the Dec cable, but both motors stalled when connected to the RA cable?

Would a poor connection cause this problem?

[1ponders] (Paul) · #2 15-02-2009, 07:39 PM

Nope, I just swapped the cables over and same problem.

[1ponders] (Paul) · #3 15-02-2009, 08:04 PM

Weirder and weirder. No moters, press the handpaddle RA buttons...Tracking Stopped!!!

renormalised (Carl) · #4 15-02-2009, 08:19 PM

Sounds like there's something screwy with the controller chip on the PCB, or the connector you plug the cables into for the RA encoders/motor is faulty. You may have to lift it out and check underneath the PCB to see whether you have worn or loose soldering. If it's not that, then a multimeter check of the pins in the connector might be warranted. If everything is OK there, check your handpaddle.

JohnG (John) · #5 15-02-2009, 08:21 PM

Hi Paul

Check your power supply, Motor Stalled or Tracking Stopped can usually be traced back to insufficient voltage.

Cheers

renormalised (Carl) · #6 15-02-2009, 08:22 PM

Come to think of it....check all the connectors and pins on the PCB's. It could be something as silly as a frazzled resistor!!!

renormalised (Carl) · #7 15-02-2009, 08:25 PM

Quote:

Originally Posted by JohnG

Hi Paul

Check your power supply, Motor Stalled or Tracking Stopped can usually be traced back to insufficient voltage.

Cheers

Problem is they're getting enough juice to the DEC motor, so unless the cable to the RA box is faulty, you'd think they'd be getting it there too.

You maybe right though.....

h0ughy (David) · #8 15-02-2009, 08:27 PM

try the voltage?

[1ponders] (Paul) · #9 15-02-2009, 08:30 PM

Quote:

Originally Posted by JohnG

Hi Paul

Check your power supply, Motor Stalled or Tracking Stopped can usually be traced back to insufficient voltage.

Cheers

Running on 16V John so should be np there. The Dec is fine.

I've just put it all back together and given it another run and it keeps stalling about 45 deg with the scope on the west. I've turned it off and tried to get it going but tracking refuses to start, and the screen says motor stalled. But I know if I pull it off and put it on the dec drive it will work fine. ?????

allan gould · #10 15-02-2009, 08:31 PM

Paul
It could be that the 3 volt battery is beginning to loose juice. Swap it over. Believe me had the same problems and it WAS the 3 volt battery. Really weird.
Allan

renormalised (Carl) · #11 15-02-2009, 08:32 PM

Was anyone trying to take a piccie of Zeta Reticulii???. That might be your problem. The gov'n doesn't want you to find out about the little Grey fellas, so they've sabotaged the scope

Gotta pullout a conspiracy theory somewhere!!!!

renormalised (Carl) · #12 15-02-2009, 08:36 PM

Quote:

Originally Posted by allan gould

Paul
It could be that the 3 volt battery is beginning to loose juice. Swap it over. Believe me had the same problems and it WAS the 3 volt battery. Really weird.
Allan

Is that much the same as the CR2032 battery on a MB??. If so, then I can understand why things might go haywire, especially if it's being used to keep the onboard electronics upto speed.

[1ponders] (Paul) · #13 15-02-2009, 08:36 PM

Quote:

Originally Posted by allan gould

Paul
It could be that the 3 volt battery is beginning to loose juice. Swap it over. Believe me had the same problems and it WAS the 3 volt battery. Really weird.
Allan

That was my thought as well at first Allan, but this is just so damn weird. I'll do that this week and see how it goes.

JohnG (John) · #14 15-02-2009, 08:37 PM

Does the motor get warm at all.....

Allan is right about the battery in the control unit, it can cause some weird responses, if it is more than 12 months old, it should be replaced anyway.

Cheers

[1ponders] (Paul) · #15 15-02-2009, 08:38 PM

Ok if the motor stalls and I swap the cables over at the motors, no go. But if I swap the cables over at the controller then away it goes again......until it stalls.

[1ponders] (Paul) · #16 15-02-2009, 08:40 PM

New battery this week!!!

JohnG (John) · #17 15-02-2009, 08:42 PM

When it is running, does the motor get warmer than normal..

allan gould · #18 15-02-2009, 08:49 PM

That little 3 volt bugger and the stupid 1 line handset are the achilles heel of the Losmandy mount

leon · #19 15-02-2009, 08:51 PM

John, although I did consider changing my battery in the Gemini Unit, I have to admit I got slack and did not do it as yet.

So from date of purchase it is still running like a dream and into its third year.

Leon

PS, I agree one night it will give me grief, I expect

JohnG (John) · #20 15-02-2009, 08:56 PM

There are 2 different types, the older Gemini's have the CR 2032 which is good for around 12 months but the newer Gemini's have a different battery which is rated for a bit longer, from memory, the one Paul has in the Observatory is the older version.