# Spirit Box white noise - PT2399 problem?



## sticky1138 (Jul 13, 2021)

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?


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## blackhatboojum (Jul 13, 2021)

I can’t say with 100% certainty but, it does sound like you have a faulty chip and that it’s latching up.  Even though it’s bypassed it will still do this and give you white noise when that happens with some circuits.  Have you tried disconnecting power to to it, waiting a few seconds, and trying the effect again?


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## Barry (Jul 13, 2021)

You probably want to order several PT2399's for builds that use them, put in a socket and swap through and find the best one for that circuit


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## finebyfine (Jul 14, 2021)

Are your tl072s legit? Counterfeit ones really show their true color and add noise in cleaner circuits like the spirit box.

I agree that it’s probably the pt2399 - just haven’t had that exact behavior with one myself.


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## sticky1138 (Jul 14, 2021)

Everything is from Tayda, never had a problem with their parts after more than a dozen orders, but I suppose there has to be a dud sometime. I swapped the TL072s with some others without luck. I'll probably order a handful of PT2399s next time, unfortunately I just placed a separate order a few days ago, wish I would have known earlier!

Also, after a few more tests, I wouldn't say it's necessarily generating more white noise beyond regular amp hum, if that means anything.


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## Robert (Jul 14, 2021)

Nothing on the PCB should affect bypass.

I would look closely at the wiring (again), jacks, switch, or even your cables.

If it doesn't pass a clean signal in bypass it's not the TL072s or PT2399 causing the problem.      The pedal should pass a clean signal in bypass even with no power applied.


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## blackhatboojum (Jul 14, 2021)

I’m an idiot and retract my comment.  I missed the part about “*NO *dry signal” in your post.


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## sticky1138 (Jul 14, 2021)

I'm probably going to end up swapping the 3PDT/breakout board, all the wires and both audio jacks here shortly. I've been messing with it for a while now with it and haven't pinpointed a bad connection yet. It makes sense that it would be an off-board issue since it doesn't have a bypass signal.


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## fig (Jul 14, 2021)

...or throw up some pics. Some of these folks can spot a mole hair on the northbound side of a southbound mosquito at 1000 paces.


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## sticky1138 (Jul 14, 2021)

fig said:


> ...or throw up some pics. Some of these folks can spot a mole hair on the northbound side of a southbound mosquito at 1000 paces.


Alright, then here's a challenge for all the aspiring entomologists on this board before I face the music (or lack thereof) and rewire a third time:



https://imgur.com/a/JpSTfhl


There is a decent amount of residue now from all the soldering and resoldering, which is why I was thinking about swapping for a fresh 3PDT/breakout board and cleaning that one later. Also confirmed that amp/guitar/cables/power supply are not the culprit.


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## untamedfrontier (Jul 14, 2021)

If you bend the LED leads so they aren't touching the case, does anything change?


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## sticky1138 (Jul 14, 2021)

The exposed legs of the LED are normally covered and positioned more neatly, but I moved them for a better view and they aren't touching anything when I test it.


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## Robert (Jul 14, 2021)

Do you have a DMM?

If so, with the pedal bypassed (and no power applied) check for continuity between the tip contacts of your Input / Output jack. 
While you're at it, make sure neither of them are shorted to ground.

Then with the pedal "active" (still no power applied) check for continuity between the tip contact of the Input jack and the IN pad of the PCB.
Do the same for the tip contact of the Output jack and the OUT pad of the PCB.


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## sticky1138 (Jul 14, 2021)

Just tried it and was able to get continuity with all your suggestions.


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## blackhatboojum (Jul 14, 2021)

sticky1138 said:


> Just tried it and was able to get continuity with all your suggestions.


Just to clarify… on the first test @PedalPCB suggested, did you have continuity from the tip contacts to ground?  If so, then you have a short and that’s no bueno.


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## Barry (Jul 14, 2021)

Can you get a shot of the other side of the board?


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## sticky1138 (Jul 14, 2021)

blackhatboojum said:


> Just to clarify… on the first test @PedalPCB suggested, did you have continuity from the tip contacts to ground?  If so, then you have a short and that’s no bueno.


No connectivity between either tip to ground.

Without the brick:



https://imgur.com/tU5BCJE


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## blackhatboojum (Jul 14, 2021)

No shorts but continuity from input to output 🤔… Have you checked your instrument cables?  Seriously, that’s the only thing it could be.  If you have continuity from input to output but no signal when you plug into it, then you have an issue outside of the pedal.


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## sticky1138 (Jul 14, 2021)

blackhatboojum said:


> No shorts but continuity from input to output 🤔… Have you checked your instrument cables?  Seriously, that’s the only thing it could be.  If you have continuity from input to output but no signal when you plug into it, then you have an issue outside of the pedal.


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 wiring?


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## Jonnytexas (Jul 14, 2021)

Did the output jack twist to where the tip connection is touching the enclosure?  Also, is there a little solder blob between 2 and 5 on the FS?


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## sticky1138 (Jul 13, 2021)

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?


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## fig (Jul 14, 2021)

$10 on the jack lug. Nice Jonny.


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## blackhatboojum (Jul 15, 2021)

sticky1138 said:


> 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.


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## sticky1138 (Jul 15, 2021)

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.


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## fig (Jul 15, 2021)

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


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## blackhatboojum (Jul 15, 2021)

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.


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## sticky1138 (Nov 21, 2021)

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?


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## JamieJ (Nov 21, 2021)

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.


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## sticky1138 (Nov 21, 2021)

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.


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## sticky1138 (Nov 30, 2021)

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. 😢


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## Bio77 (Nov 30, 2021)

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.


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