Marconi Mark 8 Camera, PSU questions

[austvarchive]

Well, part of the ongoing (6+ years) attempt to get one of my marconi mark 8 color camera chains operational, a friend came by to help get it working.

So far, the CCU appears to work fine (all diagnostic boxes appear on screen).

BUT, the camera PSU module which is known for its issues had failed, blowing the fuse each time. The PSU module was repaired, but the problem now is that the camera line fuse is still blowing, EVEN without the module in place.

The voltage was tested at the system PSU at the fuse and it measured 280v, where as according to the manual, the camera should be supplied with 180v, so we wondered if this was the cause of the blowing fuse rather than a fault in the camera.

If this was the case, why would the voltage be so high, or is this normal and the voltage gets changed somewhere else down the line?

We dont have the other volume of the manual with the diagrams for the main psu to know.

So, i wondered if anyone familiar with these cameras would know what the possible problem was and the next course of action as without further info we are rather stumped..