SOLVED Awful Waffle loud *initial* pop

[nondiatonic]

I'm getting a very loud pop when initially engaging the Awful Waffle. However, once it has been turned on once, it does not pop again unless power is removed (unplugged from power supply) and then restored (plugged in again) and then engaged for the first time after restoring power. In other words, I can turn it on and off without popping after that initial loud pop. I tried jumping the LED and that doesn't eliminate the issue. I was planning on rewiring the switch for true bypass to see if that fixed the issue, but before I went through the trouble I thought it best to post here to see if anyone has ever experienced this issue.

Thanks!

 

[PJS]

I would be checking that R2 is the correct value and securely soldered. Any circuit with a true bypass switching will give a bit of a pop when engaged, but it should not be very noticeable. R2 is the component most tasked with stopping that popping.

 

[nondiatonic]

Thanks for the reply PJS.

I checked R2 with a multimeter and it is 1M. I also successfully checked for continuity between R2 to R1 and R2 to R101.

I did some reading prior to making the original post and could only find info on true bypass popping and pulldown resistors. However, I felt this was a unique case since:
1. This circuit is not true bypass
2. The popping only occurs when first engaged (my understanding is that true
bypass popping occurs every time the pedal is engaged)

I just determined that if I leave the pedal off for a few minutes (but still powered), the pop returns for one time again and then doesn't pop unless I leave it off for a while or unplug it from power.

 

[nondiatonic]

I noticed in the schematic for Mad Bean's Hotcake clone there's a pull down resistor that is not in the Awful Waffle schematic (1M at input to ground). So, I rigged up this resistor, but no dice; still pops.

So, I tried measuring the voltage across the input and output jacks.

With power supplied to the pedal there is no voltage across the tip and sleeve of the input jack regardless of whether the pedal is engaged or not (this was after I added the additional pull down resistor). However, the output jack is a different story. When the pedal is bypassed, there is a gradual build up of voltage across the tip and sleeve of the output jack. If I engage the pedal this goes away. But, as soon as I bypass the pedal this voltage begins to build again.

 

[Barry]

Maybe a leaky electrolytic?

 

[music6000]

It's a common problem with the Hotcake on other Forums also.
Have you tried 1M resistor from Output to Ground?
Update : Try 100K as Chuck quotes further down below:
'' Here's what I think is Awful about the Waffle ''

 

[Chuck D. Bones]

Every time I look at this circuit, I get a little headache. Crowther is a clever guy. I'm not crazy about the way he implemented the buffered bypass. Still, it should work and not pop. I'm with Barry, could be a leaky C2. Music6000 raises a good point also.
Here are the obvious questions:
1) Can we see some pix of both sides of the board?
2) Have you followed the Build Docs exactly?
3) Have you cleaned the board after soldering?

 

[music6000]

Pictures are worth a thousand words!!!

 

[Chuck D. Bones]

Here's what I think is Awful about the Waffle (you see what I did there?). In bypass mode, P1 and everything connected to it is floating. There is no DC path to ground, except maybe thru whatever is connected to the OUT jack. That's not good because some pedals and amplifiers don't have a DC path to ground on their inputs. Some of the early Fender amps for instance.

If this is the problem, a resistor from OUT to ground will fix it. That resistor has to be small enough drain off whatever current leaks thru C2. I'd try 100K. I also recommend using tantalum for C2 because their leakage current is much smaller than an aluminum electrolytic.

 

[PJS]

Pop on power up and only power up sounds like somewhere there is a cap that charges up instantly on power up. That's one of the functions of input/output resistors - to slow down the cap charging and so stop the pop. It could be just as simple as the power supply caps charging up.

 

[music6000]

Pop on power up and only power up sounds like somewhere there is a cap that charges up instantly on power up. That's one of the functions of input/output resistors - to slow down the cap charging and so stop the pop. It could be just as simple as the power supply caps charging up.

If you read the other Forums on the Hotcake , it's an issue that has been going since it was cloned & true bypassed donkey years ago!
I personally don't know what all the Fuss about the pedal is anyway, I built a Handwired Eyelet version & it's Meh!
It appears to only work efficiently with AC30 or very bright Amps!
My 10 cents!

 

[nondiatonic]

Thanks for the helpful replies, y'all!

To answer Chuck's earlier questions:
1. I'll need to jump on my computer to attach my pics as the forum doesn't like the file size.
2. The build docs were followed exactly as written (with the exception of the additional pulldown resistor, but the circuit was popping prior to that).
3. I lazily skipped the cleaning step (instant gratification, instant regret).

I'll give the output pulldown resistor a shot and report back. Unfortunately, I don't have any tantalum caps at the moment to try that switch.

 

[nondiatonic]

Success!

I added the 100k resistor to output as suggested, and the pops are gone!

As thank you for everyone's help, I've attached a photo of the finished product (a reference to the film "Bad Taste". A New Zealand film for a New Zealand pedal).

Thanks!

 

[Chuck D. Bones]

Great artwork! You can mark this one SOLVED!

 

[music6000]

Yo Bro, Great Rezult!

 

[modal-wool]

Hi all, total newbie here (I have built a few BYOC kits but have only rudimentary understanding of the technical stuff) but I'm wiring this up and want to make sure I understand where to put the 100k resistor from out to ground to prevent pops. Is this literally just putting one leg of the resistor on the OUT hole on the PCB and the other on the GND hole (or is another ground point better?)?

Thanks in advance for your help

 

[music6000]

Hi all, total newbie here (I have built a few BYOC kits but have only rudimentary understanding of the technical stuff) but I'm wiring this up and want to make sure I understand where to put the 100k resistor from out to ground to prevent pops. Is this literally just putting one leg of the resistor on the OUT hole on the PCB and the other on the GND hole (or is another ground point better?)?

Thanks in advance for your help

Yep, or OUT to GND on the Footswitch or OUT to GND on the Output Jack, they will all achieve the same result !