Hi,
I am troubleshooting another 7704A power supply,
a tick mode failure. By watching the voltages while bringing the
power supply up on a variac I found that the inputs to the lv regulator were
coming up but no positive voltages were coming up. I figured this was a lv
regulator problem. I checked the semiconductors and did not find a problem. I
found c3168,c3171 bad and c3168,c3170 suspect. Checking the
zeners on the rectifier and filter board i found VR47 zeners okay but checks
open in the forward direction. How can this be. It checks open with vom and
curve tracer but reads 9V as it should on the curve tracer. It has one lead
lifted.
Jerry Massengale
