# Biasing the FETs in the M800



## griff10672 (Aug 25, 2019)

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 ??


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## Chuck D. Bones (Aug 25, 2019)

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


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## griff10672 (Aug 25, 2019)

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 ....


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## Chuck D. Bones (Aug 25, 2019)

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


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## griff10672 (Aug 26, 2019)

Chuck D. Bones said:


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


Bingo !!


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