LCQ Advantage ; No signal and failure on power supply

[atavasol]

Please help, Our LCQ has problem and don't have any signal. i run diagnostic tests and has fail in power supply. (+28 is out of range it is reading 5.6v but -28V is pass).
I think this fail, effect on RF1 and appear multiple failure on;
Multipole Det RF;Fail
Multipole RF Mod: Fail
Multiple RF Amp: Fail.
so how can i solve problem on power supply +28V?

[leadazide]

Let me first admit that I am no wizard on the older LCQ series instruments but I seem to recall that most of the voltages are somehow generated or routed through the System Control PCB.. The big board on the right side.. As the first thing I would check fuses on that board..

If you recently have had the system vented to clean the optics also check that you haven't caused a short related to the multipoles or maybe have missed a wire.. that could show up like this..

Good luck and let us know if you find the solution.