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I am trying to mod my Peavey Butcher to use EL34s. People seem to indicate that this is a pretty easy mod, but there does not seem to be much documentation on it. I am a beginner so my knowledge is somewhat limited. I was able to find the info below to use as a guideline for the mod.
Stock Schematic
http://www.schematicheaven.com/newam...ey_butcher.pdf
Mods
"Phase Inverter- change R24 and R27 to 1 Meg, R23 to 82K, R26 to 100K.
Bias- remove R53(47K) and replace with 2 wires to a 10K Pot(one end of pot to R52 hole, the wiper to hole that goes to PC board conector. Then attach a 15K to other end of pot to the hole that goes to ground.)
Power tubes-Break (cut with a dremel...) lands on PC board between pins 1 and 3, then join pins 1 and 8 with a wire.
Change R3,R5,R7,R9 from 100/5 watt to 1K/5 watt.
You should have about 515 volts on pin 3 and the bias will adjust from -53 to -31. "
After checking the schematic it does not seem like cutting the traces on the pins would work because if in between 1 and 3 was cut I would still be sending 508+ to ground after joining it to pin 8. So I disconnected pin one from the board completely and tied it to pin 8. I also disconnected pin 8 and put in 1 ohm resistor in between it and the board for cathode resistor biasing. I performed the PI mods and upped the screen resistors as listed. For my bias control I just went with a 50 k trimmer.
Now when I power on my amp none of my tubes (power or pre) light up at all. I am getting 508+ on pin 3 and -55 on pin 5 of my power tubes. I am not sure if the mods I did are incorrect or if I damaged something else while I was performing it. Anybody have any ideas?
Stock Schematic
http://www.schematicheaven.com/newam...ey_butcher.pdf
Mods
"Phase Inverter- change R24 and R27 to 1 Meg, R23 to 82K, R26 to 100K.
Bias- remove R53(47K) and replace with 2 wires to a 10K Pot(one end of pot to R52 hole, the wiper to hole that goes to PC board conector. Then attach a 15K to other end of pot to the hole that goes to ground.)
Power tubes-Break (cut with a dremel...) lands on PC board between pins 1 and 3, then join pins 1 and 8 with a wire.
Change R3,R5,R7,R9 from 100/5 watt to 1K/5 watt.
You should have about 515 volts on pin 3 and the bias will adjust from -53 to -31. "
After checking the schematic it does not seem like cutting the traces on the pins would work because if in between 1 and 3 was cut I would still be sending 508+ to ground after joining it to pin 8. So I disconnected pin one from the board completely and tied it to pin 8. I also disconnected pin 8 and put in 1 ohm resistor in between it and the board for cathode resistor biasing. I performed the PI mods and upped the screen resistors as listed. For my bias control I just went with a 50 k trimmer.
Now when I power on my amp none of my tubes (power or pre) light up at all. I am getting 508+ on pin 3 and -55 on pin 5 of my power tubes. I am not sure if the mods I did are incorrect or if I damaged something else while I was performing it. Anybody have any ideas?
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