bradley ct-471c multimeter

[m3vuv]

hi all ive one of these im repairing,just a quick question,on the amplifier board there is an axial capacitor 22pf at 750 volt,it seems sort of open circuit ,ie if i feed 100khz at 150mv in one side i get about 20mv out of the other side,the only thing i have is an air variable,can i use that in its place,in the circuit it looks like a coupling cap,regards m3vuv.

[Gyro]

Rather a dumb question as you don't indicate the input impedance of your measuring instrument or measurement setup. A 22pF capacitor has an impedance of about 72k at 100kHz.

If you're measuring with a basic dmm with meter leads etc, then you'll get loads of un-quantified parasitic load capacitance that will swamp it, that's certainly going to make it seem 'sort of open circuit'.

It presumably has a 750V rating for a reason.