Quote:
Originally Posted by Geist
...I have a room full of smoke.. Two resistors burned up.. Need to find out IF I have something wired wrong, either to the Electrolytic or the internals of the cap.. Or the External wires to the Cap or drawing too much current or wrong size (wattage) of the resistors.. The Cap is C223, the two resistors are R140 (3300) and R141 (6800).. Which is right in the area of where I have my Suspect bad socket and trouble.. 1ST Video Amp.. (6AU6)
|
Well tarnation. A sudden-onset direct short from pin 5 (plate) to ground would definitely fry those two resistors. The short could be either in the tube or the socket (possibly a char track inside the socket). You mentioned using alcohol for cleaning. Drug store alcohol (either isopropyl or "rubbing" type) contains signifigant water which if not completely dry, could cause an arc and burn a char path very quickly.
It's very unlikely C223(b) is involved. If it had shorted, only R141 would have fried, leaving R140 unaffected. That tells you the short has to be 'downstream' of R140.
With the tube pulled, and with R140 disconnected, put your ohmeter (on highest ohms scale) on pin 5. It should show infinite resistance (open circuit) to ground. Any measurable leakage would be a fault condition.