5881 to EL34 problem... more smoke and blown fuses :0(

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10/21/2000 4:44 PM

Ian Anderson

5881 to EL34 problem... more smoke and blown fuses :0( Okay, I've just done the mods for changing over to EL34's on my Bluesbreaker and soon as the power switch was flipped, boom!, flash of light and the Mains Fuse gets smoked from here to kindom come, I still don't know if I've goosed the PT (hope not)'. Here's what I did...     * Changed the screen grid resistors to 1KV/7W wirewound types     * Added a 150K resistor in parallel to the original 68K one (R3). I measured the resistance across R3 and I got 46.1K which is as good as the required 47K value called for on the 1987 schematic.     * put the EL34's in (of course)       That's it. So, what went wrong?       ... Ian

 

10/24/2000 3:43 AM
gord	Hi,     By any chance, did you check pin#1 of your power tubes? I believe that 5881 tubes have no pin#1 connection, so on an EL34, 1&8 must be connected together, and whatever used to be on pin#1 must be relocated.     Am I right about this? I'm not sure.     Gord

 

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