RV4S Camera Problem

[P968CS]

Our RV4S was halfway though placing a PCB when the downwards looking camera (fiducial camera) just went black. Checking in 'Factory Settings' Cameras 1 and 3 (the two arm mounted cameras) are dead - just a black image. Camera 2, the upwards looking fixed camera is working but very dark as the red IR LEDs are not lighting up.
I re-seated the video card in the PC and I'm hoping it's OK as camera 3 is showing an image.
Everything else seems to be working OK. Could it be a power supply to the cameras problem?
Any ideas where to look?

[Mike]

I think these all run from the same 12V supply from the control box, so start there - maybe a dried up electrolytic. there is a 9V regulator on the arm board, which I think powers the fid & flying cams, or maybe it's the illumunators. 
Dimming LEDs on the other cam could also mean a short somewhere on the 12V supply. I have a feeling the upward cam may be powered from the video card.
The LEDs for the upward cam are switched, by a relay on the arm board, so I'd sugest starting there.

[Gopher]

Very unlikely to be the problem in this instance, but the camera cables on the Arm are not exactly well assembled (or weren't on ours at any rate) and do occasionally need redoing.

[SkyWalker]

I have had problems on two different machines with cameras not working, sometimes on power up they dont work and they have cut out and gone black in the middle of a job.

Both these faults were traced back to faulty soldered joints at the pins in the 'D' type connectors at the back of the PC.

Pins were cleaned and joints redone and not had any problems since.

[P968CS]

I've solved it! Problem was no 9 Volts to the 2 cameras in the arm. This is generated from a 7809 on flying leads from the arm PCB. Ohming it showed a dead short from 9 Volts to ground. I traced the 9 Volt line back to pin 34 on the 37 way D type connector on the main control box in the bottom of the system.
Problem was a schottky diode gone short circuit on the main PCB. This is part of a DC-DC converter circuit which looks like it is switched on by the 9 Volts as the 9 volt track goes to the 'feedback' pin of the IC at the heart of the circuit.
New diode bought from Farnell and I took the opportunity to replace all the electrolytics with new 105°C variety as they are getting 'long in the tooth'.

All working fine now. Many thanks for your help and advice!

Clive