I have several 8060A DMMs. One I bought new 34 years ago ! The other I bought new (NOS) last year.
The latter was being used to measure high voltage from an ESD simulator thru a high value, high voltage resistance.
Unfortunately, I accidentally set the ESD gun a bit too high and 12 to 15kV arc'ed across the HV Gohm resistor, to the + terminal on the meter.
The voltage ranges still work fine. They work fine even through a resistance, indicating that the series VARs have not developed high, non-linear leakage.
Ohms are totally messed up and the readings have no relation to the resistance being measured, from 0 ohm shunt up to megohms.
What else I've found:
Voltage and currents present at the jacks across the resistance ranges are correct, matching the service pages and the good meter.
Conductance on the bad meter does go to zero,
BUT will show a response if I wave a hand around the face of the meter. My good meter does not do this.
I did not wrap my head around the entire design yet but my current thinking is that possibly D2, D3 were blown by the hundreds of volts which would have been developed across the VARS during clamp of the ESD discharge
. Then, this current, through a 50k series resistance, may have taken out the "O REF -" on pin 12 of the MAC.
I welcome your thoughts on this. I think the best clue may be the response to a hand wave on various ranges. Some device has been taken out, leaving some node floating, but its not clear which ... and there aren't many active devices in the path to begin with.