Tap Tempo Tremolo

[Guybrush]

Hey all

I'm just starting to put together a MusicPCB tap tempo tremolo.

I was just giving the board the once over to make sure I had everything I need and noticed 2 small solder pads that are unlabeled.

One is under the opto coupler and the other is under the TL072 chip.

Does anyone know what they are for? I can't find anything in the build doc.

Here's a photo, the pads are ringed in red.

[plesur]

They are vias, used to link a trace from one side of the board to the other. Ignore them.

[Guybrush]

Ahh, thank you.

I've not come across these before, thanks for the info.

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[Guybrush]

Next question:

The build doc says to use 22k trimpots but on the board the are labeled as 10k.

Anyone know which value is correct?

Thanks.

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[brejna]

You will have more range if you use 22k or 20k trims

[brejna]

BTW this is mine experience with it that I have post in the building thread on DIYSTOMP:
-First thing I didn't do is build it with waveform pot and that was mistake because I couldn't stop thinking about that option  , so at the end I did add that pot and it gives you  really more versatility.
-Second thing is about NSL-32, I have tried 4 of them and they all had problems with ticking and that drive crazy 'cause I could rid of it, so I grab those GL5516 ldr's that I got from ebay and wrap mine own optocoup. with white led and I got best results with them and no ticking..
-Third thing is that with those GL5516 I have noticed that you have more output if this is something interested to someone.
-Fourth thing is about that 330pF cap, raising value of this cap really helps with ticking and adding buffer in front of the pedal can remove ticking in bypass (at least in mine build)
-Finally This Tremolo is not ticking in the FX loop of the amp even when used with those NSL-32

Hope this will help you

Brane

[Guybrush]

Wow. Thanks for all the info. Really appreciate it!

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[Guybrush]

I've just hooked the circuit up to my test rig and there's a problem. When engaged there's no sound. The tempo indicator LED is working as it should and the knobs effect how fast/deep the LED lights up but there's just no sound. I have sound in bypass.

Anyone have any ideas on what the problem might be?

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[lincolnic]

Sounds like you might have something shorting to ground somewhere. Check for solder bridges and if you're using board-mounted pots, make sure they're not accidentally touching the PCB anywhere.

[Guybrush]

Thanks man. I've had a look and trimmed a few stray strands of wire but the problem persists.

Here are some
photos. Can anyone see anything obvious that I've missed?




For reference (ignore the red circles)


It's so disheartening. I was so careful when putting this one together. I was certain it would work first time.

Thanks guys

[lincolnic]

Don't give up! I don't see anything immediately suspect in your soldering, so I'd say the thing to do now is bust out your signal tester and see what's going on. Don't take anything for granted - start at the input wire and work your way through. If you get signal all the way through the output, then your circuit works fine and something's probably grounding out somewhere outside of the PCB.

[Guybrush]

Cheers.  I've not really had much luck doing this before. I can't read schematics so will need to brush up on this.

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[brejna]

I would definitely check if your input and output is grounded. Next thing could be tl072..
this circuit has very simple dry path so you will find error very fast.

[Guybrush]

I would definitely check if your input and output is grounded. Next thing could be tl072..
this circuit has very simple dry path so you will find error very fast.

Thank you. Please could you explain how to check they are grounded? I know this is incredibly basic stuff but I've just never managed to get my head around debugging.

[brejna]

Do you have DMM? if you have one set it to check connections/diodes, then put one lead on the GND connection and the other on the input and repeat same thing with output. if input or output are grounded you should here that from the DMM multimeter if a form of bip.