Pot troubles

[aettin]

Hey folks--

Built a Rebote 2.5 delay. Worked like a charm, and made the unwise decision to open it back up to fiddle... closed everything up and the delay knob is doing something weird. For about 90% of the range it works as it should, modulating the delay speed, but when turned past that 90% point, the delay doesn't get shorter, but rather really long and noisy. Yikes. Did I just break something in the pot? Would replacing it fix the tracking?

Thanks in advance.

[LucifersTrip]

the better guess is that you accidentally altered something else

you can test the pot by just desoldering a couple logs

[Thecomedian]

the better guess is that you accidentally altered something else

you can test the pot by just desoldering a couple logs

this. Without knowing what you fiddled on it's hard to tell.

[aettin]

Thanks so much for the fast turnaround. Sorry I should have mentioned that my tinkering had nothing to do with the rebote itself. I added a fuzz face clone in the same enclosure, from the same power supply before the rebote in the signal chain. Closing everything up was a bit of a squeeze. If I did pop/ break something with my cramming, is there a "go to" place to look for a problem the affects only some part of the range of a previously fully functional pot? This may be a bit of a stretch, but can a mis-set bias on the ff affect the rebote?

[Thecomedian]

how compact or messy is it? the simplest task would be to open it back up, play it again and twist the knobs to make sure its still misbehaving, then break the traces connecting the fuzz circuit output to the rebote input, and reengage the rebote with a lightly added input jack, and play it again, testing knobs again. The fact that the rebote sounds 90% like it should mean you haven't harmed that. If you actually broke anything, it probably wouldnt work at all. I think static discharge damaging the IC is probably a long shot, as usually when they're actually in a circuit, they are hardened against static buildup because of the alternate paths for the voltage build up to ground out or dissipate, and static is most deadly to ICs sitting alone with no outlet for voltage buildup.

Another question: What is the Fuzz? PNP and Positive ground or NPN and negative ground? If it's PNP and negative ground, that can cause oscillation. Does the long and noisy sound seem like the technical description of feedback? Alternatively, the gain of the fuzz could be too high for rebote being the next stage. Apart from that, there's still the basic voltage tests that you can run in the sticky on this forum.

When you built the fuzz, you do have the output cap of 0.01u which feeds into the gate of the rebote FET? In any case, I'd say measure the DC voltage at the gate, measure the voltage source, then measure after the voltage regulator where it should be 5v. Then disconnect the fuzz and re-take those measurements and see if you get a difference. If it still acts wonky after 90%, drop the fuzz from the power supply and try again.

That's about all I could imagine. The bias of the FF will have nothing to do with the rebote, only how the output signal affects the rebote's input.