SOLVED Episode Boost biasing

E

EGRENIER

Well-known member
I just completed the episode boost. Now I need to bias it with the trim pot. I’m not sure what I’m supposed to look for in terms of value or even sound.

I assume I’m biasing Q1 (2n5457) based on the trim pot location. I read in some Other thread that I should aim for half of the voltage. So when the pedal is on 9V should I read 4.5V on the collector ?

Right now full, open gives me 9.22V and if I turn the trim pot CW I can drop it to 7V. I checked and I have the right trim pot 50K.

So when facing the flat side starting from the left I read:
with pot CCW all the way
9.22V, 229.5 mV and 0

with pot CW all the way
7V, 218 mV and 0

Any suggestion ?
 
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Chuck D. Bones said:
Your JFET is too cold (Idss & Vp too low). All too common to find those on eBay. Probably the leftovers from someone else cherry-picking the "good" ones. Take solace in the knowledge that your cold 2N5457s will be useful as subs for J201 in some pedals. Ideally, you should find a hotter JFET. Doesn't have to be 2N5457. Did you solder the transistors into the sockets? What' the point of using sockets if you're gonna solder them in? Your other alternative is to reduce R4 (try 2.2K) or change the BIAS pot to 100K.
Click to expand...
Thanks Chuck for confirming my suspicions on the 2N5457!

What's that cheap Digital Screen device on Fleabay you have that measures all types of Transistors????

Just added Picture!!!
899ae22e-d35c-4819-9935-f2df4d9faf9e.jpeg
 
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