"Chris F." wrote in message
...
Yes this 30V supply is separate from the two others that drive the output
stages. There doesn't appear to be a voltage multiplier, it seems to be
directly derived and rectified from a dedicated winding on the power
transformer.
The customer couldn't remember if the display just quit, or gradually got
dim over the years, so I don't have that info to go on.....


OK. Some models from some manufacturers do derive it direct from a dedicated
winding. On some that I've seen, they then follow this either with a simple
regulator, or sometimes a series resistor. Is the supply making it as far as
the display ? Chances are, if it's present at the display heater pins ( you
still haven't told me this, and it's an important pointer as to where the
problem is ) then it's also going to be present at the display controller
IC. Report this info, and we can determine wher you should next be looking.

Arfa