My repair of Fluke 8840A is almost done. But I have a problem: AC shows hundreds of millivolts even with probes connected. When I measure higher voltages, readings fluctuate tens-hudreds of millivolts also, but seems to measure OK apart from noise.
AC option 9 PCA board is connected to mainboard thru multi-wire flat ribbon cable and J801 AC IN wire.
TP810 GND connector is not connected.
Should TP810 be connected to mainboard or chassis ground? If so, what is the corresponding contact on mainboard?
Or are my problems caused by something else? Self-test doesn't show any errors, DC is OK.