Biasing the FETs in the M800

[griff10672]

I was able to bias all the FETs in the circuit to 4.5v except for the one that says " tone " next to it ..... it was reading 8.89v ... and the trimmer wouldn't budge it .... I built two of these at the same time and the other one is doing the exact same thing ... when I plug them in to sound test them .... they sound amazing !!!!
So ... happy screw up ??? or is that one FET suppose to running that high ??

 

[Chuck D. Bones]

Would be much easier to troubleshoot if we had a schematic...

 

[griff10672]

actually someone else on here pointed out to me that that particular trimmer effects the tone ( hence it saying " tone " next to it ) ... and it indeed does effect the over all feel and tone of the pedal ....

 

[Chuck D. Bones]

That last JFET is probably a source follower and has the drain tied to +9V.

 

[griff10672]

That last JFET is probably a source follower and has the drain tied to +9V.

Bingo !!