Perplexing intermittent problems with Peppermill

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Perplexing intermittent problems with Peppermill

Postby Tinkerer » 06 Apr 2012, 04:42

I have built the Peppermill overdrive circuit at the Runoff Groove site and am experiencing some perplexing intermittent problems. Here is the circuit:

http://www.runoffgroove.com/peppermill.html

When I turn the circuit on it will work properly for a few minutes and then:
1.) stop working all together- like it is completely grounded out
or
2.) begin to go lower in volume and start emitting a static like noise
or
3.) the gain control will stop working

I have tried to trouble shoot this with a sound probe and can trace sound all the way to lug 2 of the gain pot. The first stage through the BS170 works and then there is no sound at either the D, the G, or the S on the J201. For all three of the intermittent symptoms that I am experiencing the sound has been present through the BS170 first stage, so I am thinking that my problem is in the second stage somewhere. Every time that I have used the sound probe to trace the failure, at some point in my probing I have touched different points in the second stage circuitry, and will hear a pop, and then the unit is fully functional again only to have one of the 3 failure types above reoccur a short time later. I have replaced the J201, have replaced the 1 uf electrolytic cap, and have replaced/resoldered the leads going from lugs 1 and 2 on the gain pot to the board, but the problems persist. I have examined the solder points and everything looks okay. I built this on a Radio Shack perf board like pcb. Voltage at drain on the J201 is 4.5v. Any help will be much appreciated!!
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Re: Perplexing intermittent problems with Peppermill

Postby bato001 » 06 Apr 2012, 05:09

Tinkerer, post pics of the component side and solder side of your board, along with gutshots of the pedal wiring if it is boxed up already. Maybe that will help someone figure out what is going on.
"Ever wondered how some of your favourite guitar players got their tone? Me too. Probably a good amp and lots of practice." Little Lord Electronics Homepage
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Re: Perplexing intermittent problems with Peppermill

Postby Tinkerer » 06 Apr 2012, 05:40

Well I think I figured out what is going on. I decided to probe continuity between the perf board solder joints, and I found that I had a poor connection between the S pin on the J201 gain stage and the connected components. I resoldered it and so far so good.

Thanks bato001 for the suggestions- I am a newbie poster and not clear about what to include and how to include it.
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Re: Perplexing intermittent problems with Peppermill

Postby bato001 » 06 Apr 2012, 19:15

Tinkerer wrote:Well I think I figured out what is going on. I decided to probe continuity between the perf board solder joints, and I found that I had a poor connection between the S pin on the J201 gain stage and the connected components. I resoldered it and so far so good.

Thanks bato001 for the suggestions- I am a newbie poster and not clear about what to include and how to include it.


Always include gutshots, solder side, component side and a schematic along with Voltage readings for your transistors (B C and E) and anything you have already done to try to fix it. 99% of the time someone here will be able to figure it out within a few days, if not hours.
"Ever wondered how some of your favourite guitar players got their tone? Me too. Probably a good amp and lots of practice." Little Lord Electronics Homepage
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Re: Perplexing intermittent problems with Peppermill

Postby whiskeytown » 15 Apr 2012, 15:25

I built Peppermill by http://www.runoffgroove.com/peppermill.html but there is no any sound when effect is on. I used BS170 and J201 transistors and 100Kohm trim pot. And any help how to wire control led ? I wired mine like one side trhough 1.8Kohm resistor to 3PDT footswitch and other side to + terminal on dc jack.

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