G11/Gemini slewing problem. Any thoughts? - Page 3

acropolite (Phil) · #41 17-02-2009, 07:42 PM

Paul, what Bird described is a common occurence with RJ sockets in telephone handsets, the constant movement either cracks the cct board tracks or if the solder joint is at all fragile it simply cracks that.

Often the cracks are hairline, best remedied by soldering a piece of wire back along the track.

Given what you have described that would be a good starting point. If your soldering skills are a bit average, get someone who is proficient to do it, as too much heat can quickly destroy the fine tracks that usually connect to the RJ PCB sockets.

leon · #42 17-02-2009, 08:27 PM

Bloody hell, this is getting to much for me.

Paul, I wish you well.

Leon

[1ponders] (Paul) · #43 17-02-2009, 08:53 PM

Quote:

If your soldering skills are a bit average

geez you make me laugh sometimes Phil.

"a bit average" doesn't even come close. Absolutely woeful might be closer. Completely incompetent would be better.

Hagar (Doug) · #44 17-02-2009, 09:14 PM

Quote:

Originally Posted by [1ponders]

No I haven't Fred, but it's strange it only happens in RA and always on one side of the mount in the same spot.

Hi Paul, with you r statement above it is indicating it is something mechanical rather than an electrical problem unless you have a cable dragging or moving in this position.
Have you tried loosening the the clutches fully and then operating the drive through the full range. If it still stalls it may be a tight spot on the worm gear.

I don't see you have much to continue with other than trying to eliminate one thing at a time. next would be to mechanically disconnect the servo and drive it again without load. If the motor again stalls I am afraid you are looking at cables or electronics.

If it looks like being an electronic problem have a good look with a magnifying glass for a dry solder joint. Sometimes these will only show up when current is passed and the connection heats up a little.

Good luck.

[1ponders] (Paul) · #45 17-02-2009, 09:21 PM

Doug, I've done everything you've suggested including running the servos unattached and Motor Stalled still comes up. There are no cables snagging, I've dropped the worm right down so it isn't touching the gear as well as releasing the clutches completely. I've swapped motors, cables, gearboxes, run DEC through RA and visa Versa, used the Dec motor in place of the RA motor, yet when it stalls and I remove the motor I can rotate the worm by hand with no difficulties at all. It has me totally stuffed. I believe that there is something electronic, possibly in the encoders or as Phil has suggested in the RA socket, but it's the repeatable positioning of the stall that's got me. As you suggest it sounds mechanical, but given everything I've tried I don't see how it can be.

[1ponders] (Paul) · #46 17-02-2009, 09:28 PM

JOI is there any difference between the servo motors used for V3 Gemini and V4 Gemini.

Shano592 (Shane) · #47 18-02-2009, 09:03 PM

A good rule of thumb is to change these batteries on April Fool's Day, along with your smoke alarm batteries, and any others (like car remote and motherboard batteries).

That way, you have a fixed "maintenance" schedule, on all items like this.

Bassnut (Fred) · #48 18-02-2009, 09:10 PM

Measure the supply voltage under load punk, do the easy obvious tests

If the motor is stalling not even connected to the mount, forget the mount.

leon · #49 18-02-2009, 09:30 PM

Hmmm, Fred i might have to agree there, so to try the set up with a L4 Gemini unit probably wouldn't help either,

what about if someone sent Paul a motor, to try

Leon

[1ponders] (Paul) · #50 18-02-2009, 09:41 PM

The hand paddle is saying the motor is stalled but the motor is still turning

leon · #51 18-02-2009, 09:54 PM

Gees Paul, what are we going to do with you, mate,

you have lost me. do you wont me to send you a hand paddle, as I'm away for two weeks, come Saturday.

Leon

JohnG (John) · #52 18-02-2009, 09:57 PM

If you have confirmed the motor is actually running but the hand paddle is showing otherwise, change the hand paddle cable, if you have a spare or can get hold of one, they are Mac cables I believe, replace it.

Give the cable a wiggle and see if that clears the problem, I had an intermittant problem show up when I had my Gemini, I replaced the hand paddle cable and the problem disappeared.

Other than that I am out of ideas....

Cheers

Hagar (Doug) · #53 18-02-2009, 10:15 PM

If the motor is still turning it would indicate a feedback problem from the motor encoder or a hand paddle problem. Back to cables or hand paddle or cable or a crook solder joint in the connection area on the main board.

acropolite (Phil) · #54 18-02-2009, 10:16 PM

Quote:

The hand paddle is saying the motor is stalled but the motor is still turning
.

I'm not sure what the G11 motors and encoders look like but if they're seperate, the controller is probably checking the encoders (how else would it know the motor had stalled?) and not seeing them turning therefore deduces the motor has stalled.

Hagar (Doug) · #55 19-02-2009, 08:03 AM

Quote:

Originally Posted by acropolite

I'm not sure what the G11 motors and encoders look like but if they're seperate, the controller is probably checking the encoders (how else would it know the motor had stalled?) and not seeing them turning therefore deduces the motor has stalled.

If it is similar to V4 then the motors and encoders are in the one unit. It would indicate that the encoders are fine if they work OK connected to the Dec drive cable.
The problem must be in cables or main board or hand paddle or any combination of these.

bird (Anthony Wesley) · #56 19-02-2009, 06:06 PM

Quote:

Originally Posted by acropolite

I'm not sure what the G11 motors and encoders look like but if they're seperate, the controller is probably checking the encoders (how else would it know the motor had stalled?) and not seeing them turning therefore deduces the motor has stalled.

The motor cables contain wires for both power to the motors and reading back the encoder signal from the motor to see how fast the motor is turning.

Sounds to me like the latter signal is not getting through, ie a broken wire in the cable or a bad solder joint.

For what its worth, a broken wire in the cable may also explain why the mount seems to stall at a certain point, maybe the cable is being bent just right to go open circuit.

You could check this by swapping the RA and DEC cables and see if the problem moves with it, or flexing the RA cable and see if you can provoke the problem.

cheers, Bird

[1ponders] (Paul) · #57 19-02-2009, 06:40 PM

Quote:

You could check this by swapping the RA and DEC cables and see if the problem moves with it, or flexing the RA cable and see if you can provoke the problem.

Yep, done that too bird. I have a sneaky suspicion that acropolite may be on the money with a break in the socket on the gemini side.

Leon has offered to lend me his V4 gemini, will it work with the motors I have and will he need to send his cables and hand controller as well?

h0ughy (David) · #58 28-02-2009, 12:42 AM

http://www.ovision.com/Losmandy_Pres...S_english.html just as a small distraction, what about the item in the link - might rule out the worm drive

[1ponders] (Paul) · #59 28-02-2009, 10:49 AM

I've done a bit more with it, taking into consideration some of the suggestions and advice and it looks like its the RA motor. I'll send the whole kit and kaboodle away to get looked at but I think that is all that is needed.

[1ponders] (Paul) · #60 28-02-2009, 10:50 AM

I've been tempted by those for my G11 Dave, but unfortunately the money for them has been tagged for other needs....like food and bills.