Odd Carcass/Carcosa Issue


Active member
I recently gave my Carcass build away and the new owner has experienced some odd behaviour. Unfortunately, he is now living several thousand miles away from me so I'm trying to troubleshoot "remotely" and I'm hoping some of you might be able to help me narrow the scope of potential causes.

What he tells me is that the pedal has been working fine for several weeks and then suddenly became VERY loud and the output control did little or nothing to reduce the level.

After making a few suggestions, I asked about the mode toggle to which he reported that he had been running it in the higher output mode (I think that's "Demhe" rather than "Hali") and after toggling it to the opposite setting, the pedal went back to working properly in both "Demhe" and "Hali" modes.

My first thoughts were:
1) Issue with the Output pot
2) Issue with the 3PDT switch
3) random piece of wire/solder etc. rattling around inside the enclosure making connections that shouldn't be connected
4) flaky mode toggle

Given that the output level became "uncontrollably" loud, am I right in assuming it's NOT the toggle (the output controls everything upstream so even if ALL the output is getting through/around upstream components, the output pot SHOULD still provide some adjustment if it's working properly, no?).

Anyway, apologies for the vague cry for help. Just hoping someone might be able to suggest the mostly likely areas of the circuit to focus my long distance troubleshooting.

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The "after output" control is a voltage divider on the ouput, so if that knob isn't turning the volume down at all you most likely have a problem with that particular component and surrounding circuitry. There's not much happening between lug 2 of the after pot and the output pad of the board. First/easiest thing would be to clean out the pot w deoxit, see if that helps. You could look for a solder bridge around C9? Could be a short between lugs 2&3 on the PCB?

Does the bypass switching work properly? If it does, and signal is going into and out of the board properly via the in/out pads, the "after output" control not working is (**I THINK**) going to be the first indication of where to look.
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Sorry @mdc , do you mean the "after" control or the "output" control? Based on the schematic (and my basic skills with reading them), it looks like the "output" control is still downstream of the "after" so any volume issues with the "after" control should still be adjustable with the "output" control, no?

If you are talking about the "output" control...the one that does connect to the board's output pad (as well as C9), I did try to take a look at that area (and also considered a short between lugs 2 and 3) and all appears well, but that "look" was limited to the photos the current pedal owner was able to share with me since I don't have the physical pedal in front of me.

Any thoughts on how/why a few flicks of the mode toggle might have cleared up the problem?

Another thing that I did NOT mention...a) because I don't THINK it's related...and b) because I think the solution(s) are well documented here and around the internet...is that the 3PDT creates a loud POP every time it's stomped...
If the owner can't use a soldering iron and a multimeter, it will probably be much easier for him to send you the circuit for repair.

If he can use a soldering iron, it would probably be easier for the forum members, if it's him who does the troubleshooting post.

Something that can't hurt is to tell him to use an old dry toothbrush, to clean both sides of the board, and try the circuit again, in case it's just a short from some dirt...
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All great advice @eh là bas ma

I made sure to cover those basic steps first so definitely no loose bits falling around in there.

My STRONG sense is that he does NOT solder or use a multi-meter so I have offered/suggested he let me get my hands back on it. Now that it appears to have started to work properly again, he seems hesitant to give it back.
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the 3PDT creates a loud POP every time it's stomped
I can't check on my build right now (lent it to a bassist friend), but i don't remember having a "loud pop" on this circuit, unless the volume was very high. Probably a "click" sound on activation and a bit of background noise from the gain, but nothing too prominent.

Edit : I guess it can depend on the power supply (daisy chain, etc.), effects connected before or after, making some weird interactions with the fuzz... In my experience, it works better, or at least as it's supposed to, when connected in first position of the signal chain.
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