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Vintage threads from the first ten years

previous: moocow You're right, it doesn't seem likel... -- 8/18/1999 1:10 AM

Re: Zener filament protection

8/20/1999 6:41 PM
Doc	Re: Zener filament protection If the locating peg gets broken off a tube base, and the tube placed in the socket out of rotation in a particular orientatation, there may be a problem. (I posted this scenario a few weeks ago, but I can't find the thread.) If a 6L6 was rotated by 3 pins, clockwise, one side of the heater, tube heater pin7 would go to socket pin4 (screen voltage); heater pin2 would go to socket pin7 (6v heater supply. The final diagnosis for the amp's heater winding problem happened to be the pilot lamp socket lug touching the chassis. (Both lugs of the PL socket must be insulated from ground where the winding CT is ground referenced.)

8/20/1999 6:41 PM

Doc

Re: Zener filament protection

If the locating peg gets broken off a tube base, and the tube placed in the socket out of rotation in a particular orientatation, there may be a problem. (I posted this scenario a few weeks ago, but I can't find the thread.) If a 6L6 was rotated by 3 pins, clockwise, one side of the heater, tube heater pin7 would go to socket pin4 (screen voltage); heater pin2 would go to socket pin7 (6v heater supply.

The final diagnosis for the amp's heater winding problem happened to be the pilot lamp socket lug touching the chassis. (Both lugs of the PL socket must be insulated from ground where the winding CT is ground referenced.)