Hi, hope this is not off topic - well it does measure volts...
I just received a 6517A electrometer but it appears to have a fault.
On volts, with shorted input, the reading usually drifts rapidly
upwards. For example 10mV in 10 seconds on the 2V range.
It is usually OK (stable to 10uV) at power-up, but the fault can be
provoked by tapping it lightly with e.g. a finger. Then it runs
away.
I can hear a faint noise, very like a relay switching when the unit is
tilted. Nothing obviously loose or rattling inside...
Has anyone seen this? Could a reed relay fail like that?
--
John Devereux
John Devereux john@devereux.me.uk writes:
Hi, hope this is not off topic - well it does measure volts...
I just received a 6517A electrometer but it appears to have a fault.
On volts, with shorted input, the reading usually drifts rapidly
upwards. For example 10mV in 10 seconds on the 2V range.
It is usually OK (stable to 10uV) at power-up, but the fault can be
provoked by tapping it lightly with e.g. a finger. Then it runs
away.
I can hear a faint noise, very like a relay switching when the unit is
tilted. Nothing obviously loose or rattling inside...
(replying to myself)
OK, seems like the noise was a red herring. It is caused by the front
panel bezel assembly flexing, there are metal grounding fingers that
make the noise when they slide a bit!
Has anyone seen this? Could a reed relay fail like that?
I poked around a bit more and I do think it is the relays inside the
internal shield - not sure whether to attempt a repair or not.
John
--
John Devereux