Ampeg B2-48 head bias

[BoogieZK]

Hello eveyone,
I have an Ampeg B2-48 head on the bench and i'm lazy enough to not take appart the whole pcb.

The bias is given in the schematic with which component is supposed to be measured but no markings on the board.

Can anyone help me identify the resistors on the bottom pcb please?

 

[agedhorse]

You need to be absolutely sure you are measuring the correct values, it’s an unforgivable process.

 

[BoogieZK]

You need to be absolutely sure you are measuring the correct values, it’s an unforgivable process.

Yep i know, i have the schematic and all but not the component placement on the pcb.

 

[agedhorse]

Yep i know, i have the schematic and all but not the component placement on the pcb.

Then you have done work ahead of you. Be very careful.

 

[BoogieZK]

If it's too boring for me to take appart the board from the chassis, i'll check the crossover distortion and output signal symetry with an oscilloscope and this will be done.

I'm doing this for free for a careless band, i will not sweat for that.

 

[agedhorse]

That may not be a great idea, symmetry may not change with bias, and crossover distortion may always remain under some levels and frequency ranges. Without knowing the actual baseline, you could be off by 100%

 

[BoogieZK]

That may not be a great idea, symmetry may not change with bias, and crossover distortion may always remain under some levels and frequency ranges. Without knowing the actual baseline, you could be off by 100%

Yes, i said check, not bias the beast with those info.
Ok i'll take it appart if it's what it needed.