BMP Opamp Kit – No Sound (First Build!)

[tomsgreenmind]

Hi All,

So I’ve built my first pedal, and I’ve come unstuck. I’ve read through the beginners guide here and gone through basic fault checking, but I cannot get a signal to pass through this pedal!

I’ve checked solder joints, all looking good. No dry joints or bridges.
I’ve checked polarity of components (including ICs) and all looking good there.
I’ve used continuity mode to go from input to output and my multimeter beeps.
I’ve checked each component and I’m getting a value returned on my multimeter.

I’m just testing it using alligator clips to go to a battery and jack sockets, but I cannot get a sound out of it.

Are there any other troubleshooting steps I have missed? What could be the problem here?

Thanks in advance.

[Billy]

Do you get power to the pcb and bypassed signal

Post pictures of both sides of the pcb and offboard wiring to jacks, 3PDT etc so that it can be easily traced

[tomsgreenmind]

Hi Billy,

Thanks for the reply. I get power, but no bypass signal. I haven’t wired the witch up yet as I just want to test it before going any further.

I’ll get a picture up later (it’s late here in Aus) to see if that helps.

[Billy]

Double check you’ve wired the T for tip pad on the pcb in and out to your jack tips

Its easy enough to get them wrong even if you are aware that the in and outs have one pad for jack tips labelled with a small T and another for grounding the jacks

[tomsgreenmind]

I did miss the T early on, but after reading the guide I did correct that.

I’m sending T to tips, the other pad to sleeve, 9v pad to + on the battery, ground pad to – on the battery. Does that sound right for testing purposes?

[Billy]

Yes that will work to test it as long as you have 9v powering the board, everything that needs grounding  connected to ground and your in and outs are correct it should fire right up

Are you using 2 mono jacks if using a stereo jack for in make sure you don’t have the tip or ground connection from the pcb going to the ring connection on the in jack

 

 

[Barry]

Clear photos of the board itself front and back as well as separate photos of the off-board wiring would likely be very revealing. When there is no sound the wiring is usually the suspect. If we can see it may help.

[tomsgreenmind]

Why when I post images the post doesn’t show? Has it gone to a moderation queue or something?

[Barry]

There is no queue.

Here is a photo of Rory as a test.

 

Without knowing more all I can guess is to make sure you are using the photo icon in the menu bar and uploading an actual photo and not trying to post a link.

[tomsgreenmind]

Ok, here’s another try. Maybe one picture at a time might work.

[tomsgreenmind]

[tomsgreenmind]

ok, looks like it was just an issue with putting two images in one post.

Wiring is just “T” pad to tip, other I/O pads to sleeve (using mono jacks for both), +9v to positive battery terminal and GND pad to negative battery terminal.

[Billy]

Do you have an image with the jacks and battery snap wired

A few of your solder joints look dry remove the ICs from thier sockets and reflow them all especially those that look dull

Also check you have continuity from the in and out T pads and the jack tips and all grounds

[tomsgreenmind]

Thanks for the advice, I’ll reflow the solder joints and report back. Hopefully it’s just a few dry joints.

[Barry]

When you put everything back please take a couple photos showing the off-board wiring since that is a huge suspect when there is no sound. We need to see the wiring to Jacks and the wiring to the 3PDT switch especially.

[Author]

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