Testing done by Ashtrinidad on Feb 19, 2021
Replacement board worked as specified when installed in unit. I soldered a header to the board so I could remove the PA3004 board easily. I had to cut off the pos 2 pin to get it to fit.
I manipulated board components to simulate each of the fault conditions, to make sure the chip properly shut down the relay in case of a legitimate fault.
AC Fault Testing
Tested the AC fault by lifting a leg of R411. This will present an open to Pin 7, which should trigger the fault.
With one end of R411 disconnected from circuit, relay DOES NOT pull in. AC Fault detection confirmed!
Negative Supply Fault Testing
Tested the negative voltage fault by lifting a leg of R412. This will present an open to Pin 6, which should trigger the fault.
With R412 leg lifted, relay doesn't pull in. Negative voltage fault confirmed!
DC Offset Fault Testing
Lifted legs of R347 and R348 to isolate the Pin 4 line. Confirmed that it still pulls the relay in, since it's still connected to ground through R405.
Now I put an external voltage supply on Pin 4 and began ramping the voltage up in 0.01V steps. At 0.54V, the relay turned off. I started decreasing the voltage, and it pulled back in at 0.42V
In the negative direction, it turned off at -0.52V and back on at -0.45V
Fault confirmed for both positive and negative offsets!
I confirmed that relay pulled back in once all alternations were corrected.