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RD100 Loud Hum / Bias Issue / Etc...

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Phil Vandel
Posted on Thursday, October 03, 2002 - 12:49 pm:   

Hi there. I have a RD100 Music Man that I am running into some issues with. The amp is making a loud hum and one of the power tubes (Sveltna EL34's) is glowing uncontrollably red hot the plate is roasting. I tried adjusting the bias pot to give it less voltage and it still doesn't appear to help. I have a new set of tubes to install in this amp, but I don't want to damage them if this could be another problem needing repaired. So I am wondering if anyone else has experienced this issue? Also, does anyone have the proper pins, voltages, etc for correctly biasing this amp. This hybrid thing has me all backwards. I usually only deal with old point to point stuff. What a great amp... It's a shame to have it sit in the road case and not be used because of a simple repair..... Please help. Anyone. Everyone. You can email me directly at: philvandel@hotmail.com if you have any immediate insight to this issue. Thanks a million.
Terry
Posted on Monday, October 07, 2002 - 07:11 am:   

Hi what is the bias? Is it the same on the two 3.9 resistors you may have a bad JE1692.