Problem with EQ6 motors or control board

[pmrid]

I'm trying to put my old EQ6 back into useful service as a stand-by. But have been having endless difficulty with one of the motors - or it may be in the circuit board - or even so odd combination of both.
I can absolutely eliminate gears, worms, and any sort of purely mechanical/alignment issue - because this problem occurs even when the mount is disassembled.
When the motors are connected, power applied and the usual introductory Synscan stuff is out of the way, and I send a slew command to the RA motor, the motor rattles loudly but does not spin its gears. When I swap the RA and Dec motors on the circuit board both motors run smoothly and with no protests. When I sawp them back, the RA rattles again and goes nowhere.
The motor seems OK because it runs fine when on the other connection. The RA connection seems fine because it runs the Dec motor just fine.
I am at my wits end trying to unravel this riddle. Any suggestions would be welcome.

Peter

[ZeroID]

Power supply possibly. From what I have been recently reading in the EQMOD group any voltage below 12 is suspect. The mount needs a good stable and plenty of amps output to run. The difference between the two motors might be small but enough volts drop difference for one to fail in one position but not the other.
I'd look at trying witha well charged car battery, about 13.6v and check all the plugs and connections.
I use a modified PC supply to run mine and although the red led flashes as it is a true 12v it can deliver the necessary current and doesn't drop voltage under load.

Just an idea.

[pmrid]

Thanks Brent. Worth a look. In the interim, I have ordered some NEMA 17 motors to replace these - but I can't find a source of replacement boards. Anyone have any links to such a source?
Peter
Peter

[BPO]

Hi Peter. Over here in NZ, I recently upgraded the PCBs in my EQ6 Pros and sourced the boards locally from Southern Cameras (http://www.southerncameras.co.nz/index.pasp) in Dunedin.

The NZ importer is Blaxall & Steven (http://www.blaxall.co.nz/main/), but I've always found them to be somewhat difficult to deal with, and instead prefer dealing with Southern Cameras.

Price per board was NZ$159 (~AU$120) including GST and shipping.

Just a thought should you get stuck locating the boards from an Australian source.

[bojan]

Peter,
This to me looks like the broken wire or connector on one motor cable.
By swapping them, you move cable or connector and the electrical connection is (temporarily ) established.
The stepper motor always rattles when one of the phases is missing or it's intermittent.
Power supply (low) voltage is another possibility, however unlikely in my opinion, given that motors actually work (when swapped).

[pmrid]

Thanks BPO and Bojan.
I've received the NEMA 17 motors I ordered as replacements (from automationdirect.com.au - STP-MTR-17048) but of course now have the amusing task of interpreting the wiring and preparing suitable connectors for the EQ6 control board. The new motors are 4-wire 1.8 degree (I think they are bipolar parallel type but am not sure about the proper description) and they come with a plug that does not suit the EQ6 control board and will require either a new plug or some form of adapter. But either way, I'm wondering if anyone knows which are the A, A+, B and B+ wires on the standard EQ6 motors so I can match them up with the new motors. (The product description does not use the + symbol but instead has a line above the letter - like a minus sign on top of the A or B).

Peter.

[steve000]

Can you make a video of it and upload it to youtube?

doesnt need to be big or and can have high compression. If you are willing to wait a while id be happy to come on out for the drive, check our your obs and take a video for ya maybe even have a tinker inside it.

[bojan]

It is easy, if you have the multimeter:

A-B must have some resistance (100 ~ 200ohm or so), C-D should be the same.

Between A-C and B-D there should be open circuit.
You should use the motor which works in both places as a reference.
If you swap A and B, or C and D, the only consequence will be the reverse rotation of the motor.