Quote:
Originally Posted by JohnCT
You can test the cap with a meter for value if your DMM reads capacitance. I don't know too much about doorknobs but they may read OK for value but start turning into resistors when you put a lot of voltage across them. Maybe someone here can address that. Because they're ceramic, I don't think they get leaky like paper caps do with voltage across them, but I'm not positive.
If the doorknob reads like a resistor on your ohmmeter, it's bad.
Of course, don't put any meter in the running circuit unless it's a HV probe.
John
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Doorknobs tend to fail leaky or shorted so a DMM won't catch it unless it shorts badly....I had one that leaked intermittently sometimes the set would wakeup and work normally other times it had absolutely no HV.
The best way to test a doorknob when you suspect it is the cause of no HV is to disconnect it on one end and keep use a glass object to prevent the HV from arcing at the disconnect point. Bypassing the doorknob cap (by that I assume you mean putting a short across it) is about the same as putting a gun to your foot and pulling the trigger...
The resistor in the rectifier base that has doubled in value is VERY bad and should be changed...that resistor is designed to limit the rectifier filament voltage and it's value must be precise. Too low and the HV rect filament is overvolted and dies fast, too high and the HV rect filament does not heat up enough for HV to pass through the rect to the CRT.
Your incorrect H output tube is your biggest problem right now though...Get that tube right first and then worry about the rect and doorknob if the HV stir ain't working.