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I think you mean C12, not C22. He has another cap in parallel attempting to get the required value. The spring sockets are for R100. He tries different values to get the LED intensity he wants. I have a small test box that I built to use to troubleshoot his non-working boards. I have in and...

Are you asking for a picture of the circuit board?

Hmmmm. OK. I'll get that changed and continue on...most likely tomorrow.

Update - there is a 10uf cap installed in C18 instead of a 1uf. Not sure if I have one here. If not, I'll have to get one from the builder of the pedal. I will report back whenever I get that changed. Thank you so much for the help!

Lift the IC1 pin 5 jumper and ground IC2 pin 3. Oscillations on IC1 pin 1? No. 5.16 volts Lift the IC2 pin 3 jumper and ground IC2 pin 5. Oscillations on IC1 pin 1? No. 4.24 volts After step 1, I assumed you wanted me to replace IC1 pin 5 back in the socket before doing step 2 I knew why you...

Adding another 47uf cap on Vref made no difference. PS is an Acopian 9GT100D-12GT100D. Good for 1 amp. It is dead clean at any setting on the pedal. Jumpering IC1 pin 5 to ground results in no oscillations on IC1 pin 1.

With the 2 caps in parallel, the oscillation frequency is about 60 msec, as opposed to around 85 msec IC1 Pin 7 is maybe 50mv larger than IC1 pin 1 With level cranked, IC2 pin 7 is much higher than IC1 pin 7. It is about 6v p-p. Attached pic

R9 measures 11.98K One of the field guys that I used to work with gave me the scope shortly after I retired.

Yes, probing IC1 pin 1 R7, R9 and C101 are all correct values When the oscillation occurs, Vref has the same frequency signal, but very low, as you said. I put a 100uf cap in parallel with C101 and I am able to take the gain pot higher before the oscillation starts. Scoped waveform attached...

I am troubleshooting a Nobleman OD build for a friend Symptoms: The pedal seems to work OK until the gain pot is increased. Once the pot's value is increased past about 32k, the circuit starts to oscillate. Backing the pot off stops the oscillation. Through an amp, it sounds like a...

Fixed it. When my friend built the board, he installed spring sockets for the LED resistor so he could change values until he got the intensity that he wanted without re-soldering resistors. That resistor was missing from the board when he gave it to me to troubleshoot. I remember him saying...

As I suspected then. Thanks! Thanks for the tip on using them for hard clipping !

Looking at the Mammal schematic... Why the 1N5817 Schottky diode in the power section? Isn't that just a blocking diode for circuit protection? I'm sourcing parts for a build. Just wondered if I can use something else/something I may already have. thanks...

Thanks for the replies gentlemen. I will continue to 'poke around' the tone control components. Enjoy your Holiday.

I am troubleshooting a Pyrocumulus build for a friend, as the EQ sections are not working. Since there is no schematic in the Build Documents, I have a few questions: How was the circuit board etched without a schematic? How does one troubleshoot problems without a schematic to follow the...

I just finished troubleshooting a Danube Fuzz build for a friend. Symptoms: The output was VERY low and any adjustments on the Volume or Sustain pots killed any signal that was present on the output. Here's what I found: 1) There was no connection on the circuit board between the...

If you temporarily install jumpers where I have drawn them in BLUE, that will bypass the signal switching path through the switch (see attached jpg). If that doesn't work, make sure you have the IN and OUT jacks wired correctly (+ & -). I don't have that exact jack here so I can't determine...

Cool! Thank you!

I Googled that A4 paper and got a lot of results. Can you post a link to the one you buy?