Tim escobedo's PWM Low output

[rocinante]

Heyaa

I've built a PWM as my first 1509a build and I'm tearin my hair out about the final box up.

I had it on the breadboard- sounded great and really loud. Moved it onto vero board, boxed it up- don't work. Redid all the wiring, double checked that I wasn't grounding out the jacks and now it 'works' BUT: the signal coming through is so low (as if I have it turned right down). The effect sounds the same and is not gating so I'm inclined to think that the problem isn't with the 386. It's just at a really low volume.

I've checked everything a few times and need some new approaches- anyone have any idea why I would be getting a WAY reduced signal just since I've boxed it up. Pots work fine, voltages are fine (I think) - I can post them when I get home later. It's driving me a bit crazy.

I posted my layout under fuzz schematics btw.

Thanks!

[petey twofinger]

i had one like this once , the pcb would flex a bit causing it to NOT make 100 percent connection on the chip .

not saying this is what it is , but it took me a month of hairpulling to find this out .

good luck .

[aron]

That's what the audio probe is for. Trace the signal until you hear where it gets attenuated.

Aron

[rocinante]

Thanks Aron. I completely forgot about my audio probe in my frustration. I've been away from home for a week but I have some time to tame this beast tonight. Wish me luck!!

Thanks Pete... I'll check that as well. Who knows in these tiny tiny enclosures!!

Cheers

[rocinante]

UPDATE:

Ive gone over it on with the audio probe, but it didnt really tell me much more than i knew before.  Signal out of the 386 is huge, then the signal out of the 40106 is low but works.  Basically it does what it should, but at a really low volume. But at least i now know its not a wiring problem at least.

I can obviously swap out the 40106 to a new one, but the fact that i am getting the right sound out, but at a reduced signal tells me there might be an easier fix (fingers crossed).  Does anyone know anything more about these ICs and why that might happen??

I also just took the width pot out of the equation and it didnt do anything either - although in retrospect im not sure why i thought it would.... err..

If anyone could shed some light that would be tops, otherwise Im just going to have to tear out this IC and try a new one.    Oh also - should say that i used this IC on the breadboard and it worked fine.  So unless i damaged it when i soldered it in i dont know why this is happening??

Cheers.

[midwayfair]

UPDATE:

Ive gone over it on with the audio probe, but it didnt really tell me much more than i knew before.  Signal out of the 386 is huge, then the signal out of the 40106 is low but works.  Basically it does what it should, but at a really low volume. But at least i now know its not a wiring problem at least.

I can obviously swap out the 40106 to a new one, but the fact that i am getting the right sound out, but at a reduced signal tells me there might be an easier fix (fingers crossed).  Does anyone know anything more about these ICs and why that might happen??

I also just took the width pot out of the equation and it didnt do anything either - although in retrospect im not sure why i thought it would.... err..

If anyone could shed some light that would be tops, otherwise Im just going to have to tear out this IC and try a new one.    Oh also - should say that i used this IC on the breadboard and it worked fine.  So unless i damaged it when i soldered it in i dont know why this is happening??

Cheers.

Sounds like the 40106 is bad or there's a mistake in the circuitry operating it. Just because you're getting some sound doesn't mean it's working. It's not working properly.

[rocinante]

Sounds like the 40106 is bad or there's a mistake in the circuitry operating it. Just because you're getting some sound doesn't mean it's working. It's not working properly.

So best to just abandon it and save myself a headache in trying to diagnose something that is probably effed?

[midwayfair]

Sounds like the 40106 is bad or there's a mistake in the circuitry operating it. Just because you're getting some sound doesn't mean it's working. It's not working properly.

So best to just abandon it and save myself a headache in trying to diagnose something that is probably effed?

No, just replace that one part. And/or double check all your values. :/

Got a layout, schematic, pictures, voltages? You will get more troubleshooting help if you post according to the troubleshooting rules thread, which also has lots of helpful tips.