Spirit Box white noise - PT2399 problem?

[sticky1138]

My Spirit Box, which had been working just fine for over a week, now puts out white noise/no dry signal both when bypassed and engaged, even though the LED still works. I went through the standard troubleshooting checklist (looked for cold joints, shorts, etc.) and even did a full rewire of the off-board components since I initially thought it was a bad footswitch or jack connection preventing the bypass signal, but no, same problem.

For a couple seconds I was able to get a echo/reverb on the white noise when I touched around the PT2399/transistor area of the PCB, but that didn't last very long and I haven't been able to do it since. I tested the connections of the Belton and all the other ICs and everything is secure, so that leads me to believe it could be a problem with the chip.

I've read that PT2399s can behave questionably. Is it possible my chip just crapped out? If that is the case, would you expect the bypass signal to be white noise?

 

[fig]

$10 on the jack lug. Nice Jonny.

 

[blackhatboojum]

Ok, embarrassing user error on the last part...I tried again and there must be a short since there is in fact continuity between each tip and ground. I was just being stupid with the DMM. Is there a straightforward way to diagnose whether that is on the PCB or in the

Now that you know it’s a short and if you still have it out of the enclosure, I would test it again. If the problem still I remains, I would start physically looking at everything. Others may pipe in with better suggestions but, me personally, I’d start from the input jack and work your way to the output jack, looking for solder bridges, resistor legs, wire frays, etc, that might be touching other components. Use your schematic as your map and follow the signal path.

 

[sticky1138]

Progress...maybe.

I removed and cleaned all the resin from the FS breakout and its connections on the PCB. Did the same with the jack connections on the PCB. Also replaced the Belton's socket since the clamps were getting very loose from taking it off and on so much. Soldered the transistors to the board for the same reason. Did another thorough visual inspection of both sides for shorts and cold joints, didn't see anything.

Now I have a bypass signal, but still silence when on. The LED works, but there is a significant pop sound when engaged that wasn't there before. My guess is that I cleared up some minuscule splatter shorts somewhere, but there is still something wrong, maybe another short.

 

[fig]

bummer..thought it might be easy for you. Have you probed it?

 

[blackhatboojum]

Clearing up your short circuit issue in bypass is definitely a step in the right direction. As @fig mentioned, best course of action now is to audio probe the circuit. If you don't have an audio probe, I strongly urge you to make one. They're cheap, easy to make, and is an indispensable tool for a pedal builder. A google search will give you plenty of info on how to make and use one. There's probably that same info on this forum somewhere.

 

[sticky1138]

Reviving an old thread because it's been months and I still haven't got this one to work.

I built an audio probe, and after following the schematic component by component I located a few silent connections. I double checked the solder joints on each of those, adding some heat to guarantee they weren't cold, but I still have silence when the pedal is on. Once I pinpoint some areas in the circuit where audio doesn't pass, what exactly should I do next?

 

[JamieJ]

If you have reflowed the joint and the signal doesn’t pass at the end of a component it might be a broken trace. You could place a jumper to the next component. It depends really. It could also be a damaged component as to why it can’t pass signal.

 

[sticky1138]

My next thought was to replace the components in question. They are a just a couple resistors and a cap, and don't appear to be damaged, but we'll see.

 

[sticky1138]

Swapped out 5 resistors and 2 caps there were giving me silence when probed. Unfortunately nothing has changed and it's still silent. This is truly a demoralizing build.

 

[Bio77]

When you did your test and got the bypass working but no sound when engaged, was the circuit still out of the enclosure?

My first thought when I read your OP was that you lost the ground at your jacks, since it worked for a week and then quit. You have quite a bit of paint on the inside of the box and you might not be making good contact. What's throwing me though is that the LED is still working.