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Re: Continuing Problems with MC275 Commemorative

John,

I use these amps and this does not sound right. Since both outputs do not glow we can assume the problem is with one side of that channel. Your no load DC voltages should be Pin #;
2-0v, 3-444V, 4-444, 5- -53V,7-0V, 8- .6v. I suspect one of the 220 ohm sand block resistors are out of spec. or damaged. Check them carefully.
The cherry red condition is caused by incorrect bias. You may want to check the 10uf 160V caps or the 200V 1.5 watt zener diodes. If any of these parts leak it looks like the bias could be upset. Your AC voltage on pin #5 should be 133V at rated output.
I assume you have swaped out tubes and the condition stays on the same tube socket?
Good luck.
Ron-C





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  • Re: Continuing Problems with MC275 Commemorative - Ron-C 08/16/0214:22:47 08/16/02 (0)


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