(ET) Fun in tracing problems

[Chris Zach <czach computer org>]

Ok, so we're on the trail of the elusive short. I dropped the motor, 
looked at the side wires. Two were somewhat damaged, so I cleaned, 
taped, and re-installed the wires.

Still ground fault.

Okie dokie. Took off the panel, started looking at the shunt wires. 
Disconnected everything at 4, fault gone. Reconnected main wire 4-B5. No 
ground. Touched 4-FU3:

Fault

Touched 4-Card 4:

Fault

Ok, now we're getting somewhere. Looked in the manual. Crud, the wire on 
the bottom might be 54, which means I have the wires to card4 reversed. 
Might explain the FW problems, and possibly the relay. Hope I didn't 
toast card4.

Everything 54 and up is not ringing a ground fault, so we're ok there.

Now to see what's going on at FU3, S01, and the like. Maybe the fault is 
in card4 with a blown diode caused by having the shunt sense wires 
backwards. Hm.

Chris