Double Flush

[gül]

I've just finished the Double Flush. Everything is working just fine, except I noticed that as I turn the Rate pot down CCW, it makes the LEDs stay lit all the way and all sound cuts out just before totally CCW. If I remove the 9v power wire and put it back, I'm in business again... Until I turn that Rate knob back down. I've tried a few different TL062s and a couple of different B50k Rate pots and a couple of different vactrols, same results. Any ideas what could be causing this behavior? This is a really nice tremolo, hopefully I can get it to stop doung the lock up thing.

[madbean]

That's a bit unusual. It's more typical in trems to futz out because the LFO is going too fast, not too slow. What type of LED/LDR combo did you use? If you turn the Depth know all the way up does it still happen?

[gül]

Thanks for your suggestion. The depth pot doesn't seem to have any effect on the lock-up. I tried it with depth all the way CW, all the way CCW, and everywhere in between. I messed with all the pots, same thing happens with the rate pot no matter what.

I'm using a Tayda LDR/red 5mm LED homemade vactrol. I tried a 5mm white LED, using the same LDR, with identical results. The vactrols were pulled from fully-functioning builds, so I know they work. You think it would be better to try to track down a VTL5C3?

[madbean]

No, I think the problem might be with the rate pot. Try this: put a 150 - 220k resistor in parallel with lugs 3 and 1 of the Rate pot (just tack solder it for a temporary test). If it still futzes out when you turn it all the way down then the pot is the problem. If it doesn't then there is something else going on. We'd have to take a close look at all the values of parts in the LFO section for a mistake.

[gül]

Thanks for another suggestion. I gave that a go, still got the lock-up unfortunately. I had already tried swapping out rate pots before I posted for help. I kind of figured that might be the culprit, but it doesn't seem to be. I tried Alpha and Vimex pots (both B50k) that I tested on the multimeter beforehand. (I should mention that I test every part with my multimeter before I solder them into the board.) I just went over the build doc again, insuring that I have inserted all of the correct parts in their respective places on the board. They are all correct. I'm going to go over the trace side of the board with a magnifying glass when I have more time, just to be sure there isn't something awry there. Thanks for your help.