Benson Preamp help!!  [SOLVED]

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tome.talevski
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Post by tome.talevski »

The G wrote: 18 Sep 2020, 11:09 Hmm, I reread what I wrote and it was blatantly wrong. I apologize. To make the drain voltage smaller we need to increase the trimpot resistance, not to decrease it :slap: :slap: :slap: .

I'd undo the shorting and replace the trimpot at the first JFET with a 1M potentiometer. If that works for the first JFET, you can try it at the second too.

I'm off to make a cofee...
SOLVED! after stumbling across another post on reddit I realised I needed to switch the gate and source pins on the j201's..! It was on the layout the whole time... thank you so much for taking the time to troubleshoot!

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Cigano23
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Post by Cigano23 »

Nice, congratulations. I've also spent days trying to troubleshoot a pedal just to find it was something (almost) obvious.

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andy-h-h
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Post by andy-h-h »

tome.talevski wrote: 18 Sep 2020, 11:27
The G wrote: 18 Sep 2020, 11:09 Hmm, I reread what I wrote and it was blatantly wrong. I apologize. To make the drain voltage smaller we need to increase the trimpot resistance, not to decrease it :slap: :slap: :slap: .

I'd undo the shorting and replace the trimpot at the first JFET with a 1M potentiometer. If that works for the first JFET, you can try it at the second too.

I'm off to make a cofee...
SOLVED! after stumbling across another post on reddit I realised I needed to switch the gate and source pins on the j201's..! It was on the layout the whole time... thank you so much for taking the time to troubleshoot!
Sorry that was probably my layout - I did have the pinout marked.

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tome.talevski
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Post by tome.talevski »

andy-h-h wrote: 18 Sep 2020, 23:37
tome.talevski wrote: 18 Sep 2020, 11:27
The G wrote: 18 Sep 2020, 11:09 Hmm, I reread what I wrote and it was blatantly wrong. I apologize. To make the drain voltage smaller we need to increase the trimpot resistance, not to decrease it :slap: :slap: :slap: .

I'd undo the shorting and replace the trimpot at the first JFET with a 1M potentiometer. If that works for the first JFET, you can try it at the second too.

I'm off to make a cofee...
SOLVED! after stumbling across another post on reddit I realised I needed to switch the gate and source pins on the j201's..! It was on the layout the whole time... thank you so much for taking the time to troubleshoot!
Sorry that was probably my layout - I did have the pinout marked.
No probs.. the info was there on the layout however as I’m only getting into it circuit making I overlooked it.. a lesson learnt!

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