Quote:
Originally Posted by kermit
1. I have swapped the motors around and still no luck on the Dec.
2. I have swapped the Cables around still no luck.
3.I have disconnected the worm in DEC still message "motor stalled"
4. Reconnected to the Ac/dc power supply and everything is good.
I really need to check the battery ....Vince
|
Thanks Vince.
I take it swapping the cables meant putting the RA on the DEC and the DEC on the RA, leaving them still plugged into the correct RA/DEC positions on the Gemini?
Which shows there is a mechanical issue on DEC.
Disconnecting the worm on DEC and it still doesn't drive is disconcerting. If it is working with the external PSU then this sounds as if mechanically it is ok (might still be a little tight in DEC worm though).
One would think even a low battery there would be enough power to turn the motor & gearbox! Motor tests by me (and motor specs) show 3.5A max current draw however, that said, this is a brushed DC motor that I have seen to start turning from as low as 1.2V with as little as 15~30~40mA (and lower).
Experience has shown that it is unusual to draw 3.5A per motor. Generally since they start turning at a lot lower current that absolute max I draw I generally in use per motor is 500~600~700mA, typicial I draw is 110mA!
One warning. A stalled motor can produce a very high current draw which can produce a large magnetic field spike that in turn can reduce the motors permanent magnet permeability. However, I'd expect this issue to only show up after many many stalls and as the motor aged!
So at this stage. The 12V battery does not have the capacity to drive the mount! But I am concerned that it couldn't even drive the motor with the worm disconnected!
Again, going back to the original issue. "jumping during autoguiding"...this appears to go hand in hand with the issues you are seeing now. A tight worm mesh will have highs and low points of contact which produce stiction which is more than likely causing these jumps.
Brendan