HP 410C GFI trips fault?

[wd5jfr]

Just got a nice clean one off eBay and when I tried to measure the AC line it tripped my GFI. I've never encountered this kind of fault before and can't find anything that would cause this except perhaps the transformer leaking. The schematic shows a grounded shield for pre & sec  power transformer windings. The power cord is good by substitution  and AC probe lead tests good. Also AC cal doesn't work and chopper is solid state upgrade. Any ideas appreciated.
Thanks
Hank

[George Edmonds]

Hi

If you want to kill yourself carry on using your HP 410C to measure AC line voltages.  This meter has the AC common connection connected to the case work, should you find an AC outlet that is miss wired the meter case will be at AC supply voltage.

The GFI trips are warning you of this, don’t be stupid.

HP say that this meter MUST NOT be used to measure AC supply voltages.

Engage brain and stay alive.

G Edmonds

[coppercone2]

https://www.antiqueradios.com/forums/viewtopic.php?f=8&t=273535

[factory]

Hi

If you want to kill yourself carry on using your HP 410C to measure AC line voltages.  This meter has the AC common connection connected to the case work, should you find an AC outlet that is miss wired the meter case will be at AC supply voltage.

The GFI trips are warning you of this, don’t be stupid.

HP say that this meter MUST NOT be used to measure AC supply voltages.

Engage brain and stay alive.

G Edmonds

Yes I agree this is bad choice of meter to measure line voltages, its' intended for audio or RF use.
I think we all have the same opinion as the members of the HPAgilentKeysight group and Antique Radio forum, the OP also posted this on, don't use it for AC line voltage measurements.

But the 410B & 410C manuals only give cautions, if the ground clip is connected to an ungrounded line connection a short circuit will result, also all the metalwork (probe body, chassis) would be live, even worse if the ground wire failed as a result of the short.
They state to use the probe tip only, but it would be far better to use a modern DMM with appropriate ratings, than something 50+ years old with possibly degraded/perished insulation in the AC probe leads and metal probe body.

David