19-06-2020, 07:27 PM
Reforming
I just set the current limit really low on the bench PSU and wind it up to 32V or half the max voltage of the cap if it's lower.
If it doesn't droop slowly on the meter after PSU is disconnected, then it's got no capacitance.
If it's still more than a few mA the next day it's likely not reforming and will get hot on full HT.
I do check ESR of lower voltage caps, but not usually the HT caps of valve gear.
Always make sure all caps are discharged and mains unplugged before checking resistances.
I just set the current limit really low on the bench PSU and wind it up to 32V or half the max voltage of the cap if it's lower.
If it doesn't droop slowly on the meter after PSU is disconnected, then it's got no capacitance.
If it's still more than a few mA the next day it's likely not reforming and will get hot on full HT.
I do check ESR of lower voltage caps, but not usually the HT caps of valve gear.
Always make sure all caps are discharged and mains unplugged before checking resistances.