11-10-2016, 04:13 PM
I searched for it again on the internet and ended up on a forum where they were discussing this particular type. Someone said that the Set Zero control should be fully clockwise where it should centre the needle with no valve in position, and the mA/Volt control should be set at 100mV. I did this and inserted the PM256 again, and the reading showed in the red "Replace" section. That sounded correct, as the valve is pretty ancient. I think it must be OK now, apart from the tatty wiring. I will correct that before doing anything else.
Bob
Bob
