previous: Wild Bill Chris, 198 volts on the 6V6 plates ... -- 1088259630

Re: Biasing problem with '62 Princeton 6G2

6/27/2004 6:22 AM

Chris

Re: Biasing problem with '62 Princeton 6G2 >Chris, 198 volts on the 6V6 plates doesn't really >sound right! You really should go to the Fender >Field Guide and d/l the schematic. The factory >voltages are almost double what you found.     I know and I have the schem. Hence my post as I didn't know what to do...     >The only way you could get such low plate voltage >is if when you wired up the can you crossed >something somewhere. Double and triple check it - >especially the bias tap on one plate of the 5Y3.     Nope. Octoplet (!) checked it.     >If you didn't have enough negative bias voltage in >the first place tacking in a pot won't help. If >there's not enough there's not enough!     I know, I did that *before* I noticed no neg. voltage...     >Then I'd check that bias voltage. The print says >about -35 volts - how much do you have? If it's >too low the 100k dropping resistor from the 5Y3 >could be damaged or maybe even the bias supply >diode.     Bingo. Bias diode was open. Replaced with 1N4007 and all is well.     Thanks for your help!   Chris

 

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Chris Forgot to add: 34 mA @ 299VDC :)... -- 6/27/2004 6:22 AM