First Pedal PCB Build: The Muffin

[Big Monk]

So in the interest of not messing up the board trying to get the LED to work “on board”, I simply jumped the board connections all together and wired right to the DC jack and stomp switch. It’s nice and discrete and everything is working.

Full volume tests to come.

 

[peccary]

So, this is a first.

Got the circuit all wired up:

View attachment 14376View attachment 14377

The circuit works wonderfully. The mid-scoop switch worked like gangbusters.

But, the LED won’t light up. How’s that for the polar opposite of what you would have expected when you were a newbie? Perfectly functional circuit on the first try but no LED.

I checked the obvious: it’s oriented properly, I did a continuity check from power to switch, etc. I tried a different LED.

I guess I’ll have to remove the whole circuit from the enclosure and check my connections from the underside.

Anyone have any ideas?

I might be crazy, but I feel like I read on here that some folks had LEDs (from Tayda?) where the long leg was the cathode. Should be an easy "just in case" check either way.

 

[peccary]

So in the interest of not messing up the board trying to get the LED to work “on board”, I simply jumped the board connections all together and wired right to the DC jack and stomp switch. It’s nice and discrete and everything is working.

Full volume tests to come.

I didn't realize that there was a second page here, just to explain my oddly late reply

That seems odd you got it to work that way - does that mean it might have been the switch?

 

[Big Monk]

I didn't realize that there was a second page here, just to explain my oddly late reply

That seems odd you got it to work that way - does that mean it might have been the switch?

There are two scenarios I see:

1.) I boogered the on-board LED circuit;

2.) A mismatch between the Muffin board and the 3PDT breakout board.

 

[Big Monk]

 

[burger-patty-and-bacon]

But, the LED won’t light up. How’s that for the polar opposite of what you would have expected when you were a newbie? Perfectly functional circuit on the first try but no LED.

I had an identical issue very recently and in my case, the PCB itself had no continuity between SW and the "K" of the LED. I soldered a jumper directly from SW and K LED pad on the PCB itself and my LED worked. No idea why the trace/pads were not linked but that was my issue.

 

[Big Monk]

I had an identical issue very recently and in my case, the PCB itself had no continuity between SW and the "K" of the LED. I soldered a jumper directly from SW and K LED pad on the PCB itself and my LED worked. No idea why the trace/pads were not linked but that was my issue.

In the end it turned out fine. I did the age old “solder an Resistor online with the LED” setup and went straight from the DC jack to the switch. It tucked nicely under the board and the heat shrinked resistor is hugging the side of the switch.

I just left the LED resistor on the board. I didn’t want to try and troubleshoot on the board and mess everything else up.

 

[Big Monk]

So, an anecdote:

I finished up my Aion Ares today and same issue. Circuit worked first time but no LED. I flipped it, still no LED. Continuity check from power to LED was good.

Ended up repeating what I did with my Muffin and jumped in a classic LED string with resistor in line and direct to switch.

Is this a common thing or am I crazy?

 

[Robert]

On either of these builds, were the leads of the LED touching the metal LED bezel?

 

[Big Monk]

On either of these builds, were the leads of the LED touching the metal LED bezel?

On the Ares, no. Now that you say it, I can’t remember on the Muffin, although I’m pretty sure the bent leads still had clearance.

Thank you for this. I’m gonna keep this in mind on future projects.

 

[Coda]

On the Ares, no. Now that you say it, I can’t remember on the Muffin, although I’m pretty sure the bent leads still had clearance.

Thank you for this. I’m gonna keep this in mind on future projects.

The legs on mine were well insulated from the bezel. Also, when I installed the second one, I soldered it before installing into the bezel. Dead for both. Literally dead, once removed, neither LED worked anymore.

 

[Big Monk]

The legs on mine were well insulated from the bezel. Also, when I installed the second one, I soldered it before installing into the bezel. Dead for both. Literally dead, once removed, neither LED worked anymore.

The more I think about it, I don’t believe the Muffin had the leads touching either.

 

[Big Monk]

On either of these builds, were the leads of the LED touching the metal LED bezel?

Turns out I need a lower RLED. I kept the jumped in LED for the Muffin and my Aion Ares but just subbed in a 1k on my Tearjerker build and it lit right up.

 

[Chuck D. Bones]

I've been going with lower values of that, like 3.3nF and 2.7nF

I originally started messing with these based on the Elk Sustainar which had like 390pF, but it sounded very bad lol

I know the R and C values form low and high pass filters, but I don't understand what effect changing the cap vs changing the resistor has

The resistor and cap both do the same thing. You can fiddle either one. No magic here, use TSC and your ears to find what you like. Personally, I like it flat in the middle and I don't want the treble side to sizzle too much. You can even leave out the resistor on the treble side (R2 on the TSC) for less bass cut. A very versatile and often misunderstood tone control.

 

[Chuck D. Bones]

So, an anecdote:

I finished up my Aion Ares today and same issue. Circuit worked first time but no LED. I flipped it, still no LED. Continuity check from power to LED was good.

Ended up repeating what I did with my Muffin and jumped in a classic LED string with resistor in line and direct to switch.

Is this a common thing or am I crazy?

The only time I had problems with LEDs on PPCB boards it was self-inflicted. Wiring error, bad solder joint at the switch or LED lead touching the bezel. I recommend putting some insulation on the LED leads so they can't make electrical contact with the bezel.

 

[Big Monk]

The only time I had problems with LEDs on PPCB boards it was self-inflicted. Wiring error, bad solder joint at the switch or LED lead touching the bezel. I recommend putting some insulation on the LED leads so they can't make electrical contact with the bezel.

In this case, the stock RLED in the build doc was simply too high. I dropped it to 1k and it was all good.

4.7k seems pretty high to me in general.

 

[Chuck D. Bones]

Depends on the LED. The aqua LEDs I use are way too bright with 4.7K; I use 22K with those. The UV LEDs I have need 1.5K or lower to be visible.

 

[fig]

The resistor and cap both do the same thing. You can fiddle either one. No magic here, use TSC and your ears to find what you like. Personally, I like it flat in the middle and I don't want the treble side to sizzle too much. You can even leave out the resistor on the treble side (R2 on the TSC) for less bass cut. A very versatile and often misunderstood tone control.

Thank you for this. I had a note to study this interaction and this gem will fit nicely.

 

[Big Monk]

Depends on the LED. The aqua LEDs I use are way too bright with 4.7K; I use 22K with those. The UV LEDs I have need 1.5K or lower to be visible.

Right! Lesson learned for for me. I’ll breadboard the LEDs from now on to get the right value resistor.

 

[Chuck D. Bones]

Thank you for this. I had a note to study this interaction and this gem will fit nicely.

If you want to simulate removing R2 in the TSC, make R2 10MΩ. Experiment with different tapers because for some R & C values, most of the action is at one end of the TONE pot's rotation.