Electronics > Repair
East Tester 5410+ not drawing current.
morris6:
Correct, within normal operating range the opamp inputs have equal voltage. But that's only when the circuit, feedback, is functioning correctly. So with all good components in place.
U1 is possibly damaged and loading the -10 V. rail too much. So, when after removal U1 the rail comes back to the normal value this confirms U1 is damaged.
Luv2Learn:
I pulled U1 and it is -8.5 now. I also noticed Q3 getting really hot. Not sure if that could be related to the issues with voltage on U14. Q 1-3 appear to be in bad shape though.
morris6:
Q3 is on the slave board that's supposed to be disconnected for trouble shooting..?
Remove the slave board and the three power mosfets Q4, 10 and 11 and the maybe shorted resistors. Then measure the -10 V. rail again. Don't put any load on the thing in this stage. If the -10 rail comes up to around -10 V then install Q11 that you measured to be good. Then see what happens when you put some load on the thing to confirm some operation.
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