N_Cook wrote:

John wrote in message ...

I checked all primary ICs voltages: always 0.
PowerOn signals goes into a custom card, which seems to act as a

controller.

nearby there's a current sense and other stuff.
Then, output signals from this custom card seem to go into the

optocoupler,

to the primary side. No voltages around the optocoupler...
I begin to suspect the custom card.
But I can't desolder it. It's in a bad place, I need to desolder other

stuff and

only with a small desolder pump ...



So what hapens if you cut the control line to the opto and power the opto
LED on via a droppered battery for a moment.


I see comment about 0 volts all over it.. My question would be, is there
any AC coming in and rectified DC ? Switches, etc...

Kind of reminds of the IBM service desk trying to help some one with
their new computer. The screen is dark. After numerous steps given to
the customer to resolve issues, it was then ask if the customer could
look in the back to make sure everything was plugged in. When the
customer indicated he needed to get a flash light to do so, he then
commented about losing power to the house.

Of course, most here know the rest of that story, but it is a simple
matter of starting at the fuel pump and working your way to the tail
pipe.

Jamie