need help with liverpool to 36w tmb conversion

[pinkmarkos]

hello everyone- i am new to this forum, and i would appreciate any input on a problem i'm having with my attempt to convert my TW liverpool to a 36w TMB. I am only using one channel (TMB high input) through the CF tone stack, and then through the liverpool's power section. I am only getting very quiet amount of sound with both the volume and master dimed. I am getting audible pops when I test the plates of the EL84s and the PI, but no sound from V1 or V2. I used the preamp board from the liverpool and ran the 36w pre on it. My pots are, from left to right on the pic, vol 1M, treb 250K, mid 25K, bass 1M, and MV 1M. I checked for cold solder joints, bad resistors, traced the circuit as best I could. I checked preamp tubes with another amp and they are all good. I am also using the B+ volages from the liverpool, which are a little different than the 36w. I will include my voltage chart and a few pics of the preamp wiring if anyone would be willing to check my work. Thanks again for any input!

V1 p1-137, p2-input, p3 1.05. Other triode not used.

V2 p1- 134, p2- vol input, p3- 1.00
p6- 214, p7- 134, pin 8- 134

V3/PI p1,6- 246, pin2,7- 199, pin3,8- 215
*can't figure out why the grids and cathodes aren't correct

EL84s- plate 337
screen 315
cathode 18.8
bias resistors 150 ohms each side to bias approx 12w each

[darkbluemurder]

V3/PI p1,6- 246, pin2,7- 199, pin3,8- 215
*can't figure out why the grids and cathodes aren't correct

These voltages are definitely not correct. You should have about 60-80V on the cathode (pin 3,8) and about 50-60V on the grids. I would try another tube and recheck the wiring of the socket.

Good luck
Stephan

[pinkmarkos]

thanks! i forgot to ground the PI cathode (duh). it was grounded through the NFB of the liverpool, but when i removed it, i forgot to reground the PI cathode. amp sounds great now! i like the TW express that i built, but that preamp through the EL84's was just too much. and i missed having a marshall-y voiced amp in my lineup. thanks again!