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Weird static pop on first third of Vol pot, Rullywow VaporRay

Started by hot_rod, March 01, 2019, 11:55:08 PM

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hot_rod

Hi - relatively new to pedal building. Some successes so far that I will share later. But one issue today I can't solve - I bought two Rullywow Vaporray PCB (among a few others!) My first VaporRay worked great. Second one looks the same internally, but I do not have any sound. When I turn the Vol pot I get no signal for first third and then a static pop and the LED comes on. I have attached a video showing the issue, mind the volume of your ears/speakers/headphones since there is a static pop.

I checked and I am using the correct pot (B10k) and I checked the solder lugs and they look okay. Could it be a bad pot?  Thanks for your feedback.


hot_rod

update: I removed the old pot, put in a new B10k and am still having the same issue. So wasted a pot but I guess I know it likely isn't that (unless whole batch are duds). What should I do to troubleshoot next? All the wiring looks correct and the soldering looks ok...should I reflow all the joints on my stomp switch? I have not tried that.

I am also slightly concerned that at the lowest Vol pot setting, the LED turns off.  (see video in first post) so probably indicates a problem somewhere else? I made another VaporRay exact same way and it all turned out great so I am stumped here.

no to mention that while troubleshooting it I noticed a burning smell from the pedal...  ???

hot_rod

tried it again, that Vol pot is the one getting hot and making the smell.

somnif

Any pictures of the board inside? If the pot is getting hot it sounds like you may have a short across it.


hot_rod

tried to show a few diff angles. bent the pots up to get the photos. they have the smallbear pot covers on them, and I can't see any two solder points touching (in some angles it looks like it but others you can see they aren't)  looking at the full board the Vol pot is upper left of the four, as you can see on the reverse side where it is labeled. Also the vol pot doesn't have much solder since I wasn't sure if I would be swapping it out again but same issue even with less solder than before.

any help you can give is great, I can't spot the trouble.

midwayfair

Post voltages. Take them on the volume pot, the input, LED, and the VR and 9V points in the schematic. (You might as well check that the chip's voltages are correct while you're at it.)

Static when turning a pot is an indication that you have DC across it.

hot_rod

I had to order an alligator clip but will get to this in a week or so, thx. still broken!