Hi all
I recently bought a Fluke 8920A true RMS multimeter. In the first days it was working, but now it doesn't measure anything. In Auto, with nothing or 1Veff @1kHz at the input I see 0.00 - 0.17 - 0.48 - 1.72 - 2.23 - 4.09 - 5.14mV (millivolt!) or similar values.
At a first time, I noticed something strange in manual mode... Now I don't remember exactly (in the meantime my father died...

), but scales were wrong in manual ranges. So I carefully opened it and touched the resistor and the jumper on the socket near the backside, after touching the screen to discharge possible static electricity. It seemed to change something in readings, but only a few...
I removed the board (with power off) and replaced it, hoping for false contacts, but after some tests it stopped working.

Now, between TP201 and TP202 I read only a few millivolt instead of 500mV. +5V, +15V and -15V are ok.
Voltage selectors have been ok since the first power on (I switched them from 110Vac to 240Vac).
Looking at the manual, I have done tests from Step No.1...5 (page 52) to 17, 33, 45 reading wrong values.
Can you help me?
P.S.: Which is the "ground"?... The gnd of the 7805 is different from the PCB metal shield! Why???...
Thanks
Gianluca