lowell 7/30/2018 8:41 PM
Fender Bassbreaker 45
Anyone willing to email me a schematic on this? Fender will not send one. This amp has low Vscreens even with the 1-45W knob at 45W. 300vdc on screens. 400+ on plates. I'm thinking the FET may be bad BUT would prefer to know that the gate voltage is correct and that surrounding voltages are in line.

Otherwise if I need to proceed with no schematic... any suggestions? These voltages are at 45w. Gate voltage seems low to me.

MOSFET voltages
G 311v
D 441v
S 306v
g1 7/31/2018 12:23 PM
What is the max clean power out you can get from it?
John G 7/31/2018 2:24 PM
You may want to read this thread, it my be useful.

lowell 8/2/2018 2:49 PM

24.5watts of clean on 45w setting at 1khz 180mv input

Quite low

John I read that...thanks. Unfortunately there's no screen voltage mentioned pnce the repair was made.
lowell 8/2/2018 2:52 PM
Whoa hold up... Had the impedance switch on 16 and my dummy load is 8ohms. Got 40watts!!! So I guess its working fine.
g1 8/2/2018 6:20 PM
If that's a nice clean 40W, then it's probably around 45 with the THD it's spec'd at.
If the wattage control seems functional, then it's probably OK.
Was it in for some other issue or was low power the complaint?
lowell 8/3/2018 9:51 AM
Is a bit farty on the low notes. I asked if it wasnt like that when he bought and he said it wasn't. All I can do is say it's putting out the right amount of clean power at this point. IMO it sounds correct... and is a matter of tone settings and gain structure. And yes I get 60watts if I go into clipping. So 45watts is a peice of cake.

I set my sig generator at 300hz and the amp clips way earlier so it seems there's more gain in the low mids. However I was still able to get 40watts clean at 300hz.