pignose g 40 v- one sick piggy ...

[es125tcd]

Kids bought me a used pignose g 40 v for xmas - got modding bug , and started swapping out preamp tubes- had some 12 au7 nationals hanging around, swapped out the 3 12 ax 7's - all went well, a little volume loss, but better tone - did some reading on the ' net ( this amp is supposed to be self biasing) so I swapped in a pair of rca blackplate 6v6's( vintage early 60's) to replace the 6l6's that were stock in the amp- had the "tone of the gods" - (think early princeton/ deluxe tweed tone- early breakup, nice warm tube tone) for ABOUT 5 MINUTES - then she died- has very low volume, and has that funky., "out of phase " tone( tone you used to get from a blackface fender tube amp, AFTER you switched it off , and it was winding down) swapped back in the 6l6's , and original preamp 12 ax7's , still the same- did I blow the output transformer ( I read something about replacing an internal fuse in the output tranny on this amp, but couldn't get any specifics on it- electronic skills are limited ( used to install telephone central office switching equipment, so I probably can still stumble through wiring diagrams, and still have an old vom hanging around somewhere in the garage) would appreciate any help in steering me in the right direction !!! loved the tone of this amp with the 6v6's in it - do these run at a higher plate voltage than a 6l6 ??? any help steering me in the right direction would be appreciated !!! GB.

[JosephB]

something tells me you arent supposed to switch out 6v6's for 6l6's...theres definitely a plate voltage difference among other things...im not sure of specifics, but that sounds wrong

[JD0x0]

you shouldnt swap 6v6's for 6l6s. one of the problems is it changes the impedance. so its quite possible you blew the transformer

[lostpick]

a lower rating power tube to replace a higher rating power tube
will overload the tubes and blow them and possibly other components
directly linked to the power stage...

next time you get an urge to swap...

put it out in the forum...

i am sure youll get more responses that can help
you with a recovery plan

good luck

[wnorcott]

6V6 are not compatible tubes with 6L6 in other words you cannot change a 6L6 to a 6V6

It is possible though difficult to replace 6V6 with 6L6 but you have to rebias the amp and it still might not work properly after that and you risk blowing your PT as well.

Generally unsafe operation in either direction.

Swapping tubes, in general, swapping preamp tubes is much safer than trying to change out power tubes.

Bill

[muchxs]

Originally Posted by wnorcott

It is possible though difficult to replace 6V6 with 6L6 but you have to rebias the amp and it still might not work properly after that and you risk blowing your PT as well.

Very possible and not at all difficult in a cathode biased amp. The G40 isn't a cathode biased amp.

Originally Posted by es125tcd

Kids bought me a used pignose g 40 v for xmas - got modding bug , and started swapping out preamp tubes- had some 12 au7 nationals hanging around, swapped out the 3 12 ax 7's - all went well, a little volume loss, but better tone - did some reading on the ' net ( this amp is supposed to be self biasing)

It's fixed bias. Non-adjustable fixed bias. See schematic:

http://www.schematicheaven.com/newamps/pignose_g40.pdf

All your power supply node voltages are listed in the schematic. Refer to all the usual "don't kill yourself" warnings then get in there with your multimeter and check voltages. Reference voltages back to the schematic or we may not know what you're talking about.

Originally Posted by es125tcd

so I swapped in a pair of rca blackplate 6v6's( vintage early 60's) to replace the 6l6's that were stock in the amp- had the "tone of the gods" - (think early princeton/ deluxe tweed tone- early breakup, nice warm tube tone) for ABOUT 5 MINUTES -

It's roughly a JCM800 using 6L6 tubes. 416V on the plates which is less than a Deluxe Reverb so the 6V6 swap would be incorrectly biased, incorrectly loaded but possible. If it were cathode biased the swap would be plausible... but it's not cathode biased.

Originally Posted by es125tcd

then she died- has very low volume, and has that funky., "out of phase " tone( tone you used to get from a blackface fender tube amp, AFTER you switched it off , and it was winding down) swapped back in the 6l6's , and original preamp 12 ax7's , still the same- did I blow the output transformer

Dunno. You could get in there with a multimeter and find out. Refer to all the usual "don't kill yourself" warnings. Hint: If the amp still has output, you might have cooked one side of the primary. Measure voltage at the 6L6 plates (carefully!), if you have voltage on one plate and not the other then you cooked it.

On the other hand it's probably something simple...

Originally Posted by es125tcd

( I read something about replacing an internal fuse in the output tranny on this amp, but couldn't get any specifics on it- electronic skills are limited ( used to install telephone central office switching equipment, so I probably can still stumble through wiring diagrams, and still have an old vom hanging around somewhere in the garage) would appreciate any help in steering me in the right direction !!! loved the tone of this amp with the 6v6's in it - do these run at a higher plate voltage than a 6l6 ??? any help steering me in the right direction would be appreciated !!! GB.

Yes the amp has an internal fuse. No, it doesn't protect the OT. If the amp still makes sound the fuses are intact.

Take and post pics. Look and smell for burnt parts.