Build Shit - DIY - What's On Your Bench?

[amishrobots]

AstableMultiVibrator BreadBoard

One of my all-time favorite circuits

[crochambeau]

I'm working on a VCA.

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Some operational hiccups aside,

the circuit shows promise.

Next build out will include matched transistors instead of the random grab from above.

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[FAP]

Coming soon:

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[FAP]

Ah, screw it: I was going to do a longer post breaking down the build process and yadda yadda... but long story short, I modded a Boss TR-2 Tremolo, and I now need your help.

When I had this godforsaken thing all splayed-out & discombobulated, the "DISTORTION" switch (aka SW102, see below) worked wonderfully. Now it essentially mutes the output signal if either DEPTH or COMPRESS pots are turned counter-clockwise.

I think I've got the problem narrowed-down to one of three potential causes:
1. D102 acting as a diode straight to ground,
2. not enough resistance on R105, and/or
3. +5.5V not being an appropriate voltage source for D102.

My theory is that because SW101 & SW102 now add two resistors in parallel [both of which go straight to ground via D102] with the resistance between VR03 - lugs 1 & 2, this is causing some circuit shenanigans where there were none before.

To clarify—and part of why I believe this—I originally had +4.5V as a source to power D102: this worked on the breadboard. Later on—without testing, my mistake—I thought it'd save me a wire if I used the existing +5.5V source (via point "K," connected to VR03 - lug 1) instead. From what I understand, the +5.5V to +4.5V range is important because that's what IC1 is expecting; it only has 1V to work with to make the volume fluctuations that power the tremolo effect. So maybe, if I use the lower of the two voltages (or a different voltage entirely) that might solve the problem. I may just try that regardless if anyone responds to this post, but I digress.

To clarify, again: the only things that changed from breadboard to assembly were the change from +4.5V to +5.5V and the addition of D102 entirely (for testing purposes, I didn't see the need to add a "status" light just yet). I also thought I needed to switch IC3 out with a beefier solution (right now it's a SIP 4558, instead of two stacked 4558's that were in there when I got the pedal), however tests have demonstrated this not to be the root cause of the issue... though I suspect stacking two 4558's might help reduce the "clicking" noise of IC1 (a commonly cited complaint of the stock TR-2).

Anyways, if anyone wants to take a crack at this I appreciate it. I don't expect anyone to do so.
This build has taken me nearly five months to complete: for this and other reasons, I plan on backing away from building shit indefinitely to focus on my personal life and, to a lesser extent, making noise... instead of being consumed by the tools to make noise.
I'm exhausted

Full schematic with my mods:

Original schematic with some corrections (the one on experimentalists anonymous has several typos):

PCB guts (why not, it might help):

[FAP]

Okay, scratch all that: turns out the +4.5V source was the correct one to use. We're all good now, except for the clicking noise on the output which I can live with. I've attached the updated images for posterity.

Now I'll take that break

[crochambeau]

Congrats on sorting it to a point at which you're happy. I was absolutely not in the position to digest the operation of the original circuit and superimpose that over the modifications you have made in order to derive ideas for why it might now be malfunctioning. I'm not smarts enough for that.