Hi,

I'm trying to figure out a dead monitor power supply that uses a UC3842B
controller. I'd like to hook my scope to the chip and observe any signals
during startup, etc. Since this is connected to rectified line voltage on
the ground plane and a large power resistor on the vcc line, I'm unsure
where to hook my ground for the scope probe. I'm using an isolation
transformer, variac and series light bulb in addition to the scope.

I'm just a tinkerer used to scoping clock signals on TTL circuits and
hesitant to do something that will toast my scope.

Any suggestions? Oh yeah, no schematics for the monitor either. I'm
looking at a similar schematic using the same control chip. I see the
startup voltage of +16vdc and no reference voltage or output strobe signals.

Help!

Kirk S.