Sheepylove Hebridean J201 (IDSS)?

RICHB555

RICHB555

Active member
I’m working on the Sheepylove Hebridean and for Q2 and Q3, the board has two spots for J201s. The J201 to the right has an indication for IDSS but not on the left. There is an arrow pointing to the left side J201. The build doc indicates measurement is required for IDSS and a higher value should be used. @Chuck D. Bones or anyone, can you advise what should be done to populate the J201s? Do I populate all four areas, and put higher value J201s where IDSS is indicated? First time I’ve run into something like this on a board. Thanks!
 

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You got it right. If you turn over the board, you should have the resdef. That's Q3 and Q4. The build doc says that the Idss in Q4 should be greater than that of Q3. The arrow on the board is just showing you where Q3 is.

Test your MMBFJ201/J201 for Idss and make sure Q4 has higher value than Q3, and Q2 > Q1.
 
szukalski said:
You got it right. If you turn over the board, you should have the resdef. That's Q3 and Q4. The build doc says that the Idss in Q4 should be greater than that of Q3. The arrow on the board is just showing you where Q3 is.

Test your MMBFJ201/J201 for Idss and make sure Q4 has higher value than Q3, and Q2 > Q1.
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Thanks 👍
 
It's a great pedal! Impossible for me to build before Chuck's advice. To me it sounds like the ultimate Dumble sound, with a hint of Marshall. Mind you I have never played a Dumble of course!
 
Finished one today. I still need to test the J201s for Idss and I've got a tester on the way. For now (on a test rig) it's a very high gain distortion and a bit noisy. The testing rig seems to do add noise. The example on the OKKO web site are not quite so insane as what I have for now. Needs dialed in once boxed.
 
Sometimes you need to adjust the bias of the JFETs differently from the original units. The lower the drain voltage the dirtier the sounds seems to get. Raising the drain voltage can clean things up but go too far and the sound can get a bit shrill and kinda strained.
 
Strat68 said:
Finished one today. I still need to test the J201s for Idss and I've got a tester on the way. For now (on a test rig) it's a very high gain distortion and a bit noisy. The testing rig seems to do add noise. The example on the OKKO web site are not quite so insane as what I have for now. Needs dialed in once boxed.
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Hope you can get it the way you like. I’m having trouble with mine. The build is finished but not getting signal when active. I got a few readings last night and I get normal numbers on the IC but zeros across all legs of the J201s. Will audio probe next.
 
RICHB555 said:
Hope you can get it the way you like. I’m having trouble with mine. The build is finished but not getting signal when active. I got a few readings last night and I get normal numbers on the IC but zeros across all legs of the J201s. Will audio probe next.
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The original pedal sounds great so I hope to get close. But I would be happy if the excessive noise goes away. This is my second Sheepylove pedal I built with unacceptable noise. I’ve build many high gain pedals without this much noise.
 
Strat68 said:
The original pedal sounds great so I hope to get close. But I would be happy if the excessive noise goes away. This is my second Sheepylove pedal I built with unacceptable noise. I’ve build many high gain pedals without this much noise.
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Happy to troubleshoot if you want to upload some pics. I don’t have any noise issues so I’d be interested if others are experiencing this.
 
szukalski said:
What was the other one? If you have a troubleshooting thread, point me there.

In general, I won’t release a noisy pedal (or even one I feel is meh) because it’s a poor experience, so I’d be interested in seeing what you’re finding.
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The other one was Hot Teacher. I
szukalski said:
Evidence of the recent troubleshooting/not-worth-it pile. It's probably 50/50 in there..

View attachment 123627
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I have at least a couple dozen of these in a drawer. I've been able to resurrect a few. Especially some built years ago when I knew much less about what I was doing in regard sto debugging.

I'll wait to post photos. I just found several what were most likely a fake J201s, one of which I used. Here's what I posted on another thread on measuring Idss values:

I just got the tester (FNIRSi LCR-P1) shown above and the SMD J201s have comparable readings in the 500ua range. I also have some questionable thru-the-hole J201s where the Idss are all 0.16ua. Then I tested some sourced from PedalPCB and their readings compare to the SMDs.

I don't know what effect the fake ones would have in this circuit. I just tested another bunch of TTH J201s ande their readings match the SMDs and sometime are 50% higher,
 
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szukalski said:
Happy to troubleshoot if you want to upload some pics. I don’t have any noise issues so I’d be interested if others are experiencing this.
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Thanks. The rig I use to power and do I/O for an unboxed board seems to add noise. I'm going to box this one and see what happens.
 
szukalski said:
What was the other one? If you have a troubleshooting thread, point me there.

In general, I won’t release a noisy pedal (or even one I feel is meh) because it’s a poor experience, so I’d be interested in seeing what you’re finding.
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Once it was boxed almost all the noise (hum) disapeared. It's not silent through my tube amps but I think that's an issued with them or the exensive cabling. But it is silent through my Blackstar Fly solid state amp on my bench.
 
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