I am trying to bring back a SDU 100, HV section will only go up to 120volts. good 220 going in. I had put in all 3 new transistors. Caps look new. diodes checked out, put another VR in, it still hangs tight at 120v andwon't light the displays. should I just replace all the HV section? kind of stuck at the Moment, don't really need it but would like to have it as a spare.

#4 8 years ago

80spit

Pinside member

Morgantown, PA

11y 78,300 862 31

Quoted from barakandl:
In my XP, low but adjustable high voltage is usually the zener diode.
Since you replaced that, how about c26 filter cap?

I only pulled one end of the Diodes to check them, I will change the zener out and see what happens.
the VR does adjust the voltage just max's out at 120volts

#6 8 years ago

80spit

Pinside member

Morgantown, PA

11y 78,300 862 31

Got it, Andrew, you were right, Sure do appreciate your help, temporarily stole the VR1 out of a working board and got this board working again! got some 1N5275's on order, Sure is great to
see a board come alive again.

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