Chaos Machine circuit noise

[proffbass]

Hi,

I tried out my new build and got a car alarm high pitched oscillating sound from it.

Here is a clip I put on Youtube so you can hear it. This clip is with the input cable removed from the pedal.

I pulled out the input cable and the sound continued.

I tested my circuit before putting it in the enclosure and didn't hear anything wrong but I hadn't connected two of the pots or the LED. Or input connections, expression pedal inputs etc.

Can you please advise me how to go about diagnosing the issue?

Let me know what sort of pictures to supply if that would help.

Thanks.

 

[z2amiller]

Pictures of the soldered side would be helpful (though of course kind of difficult to see everything with the pots in the way).

Pot in bottom right of picture looks suspiciously soldered. (Middle pin may not be making contact). Dunno if that'd cause
those specific issues or not. Really all of the pots look like they could use some more solder.

Where'd you get your TL072's, do you have any others from a different source? Sometimes those are counterfeited
but if you got them from Mouser/Digikey you have no need to worry.

Do you have an audio probe? They are tremendously helpful in situations like these, to find the place where the oscillation
starts can really narrow down the search space.

 

[leadfoot]

Are you going to use the exp jacks? If not, you need to solder the T-TN, R-RN, and S-SN holes as shown in the build doc.

 

[proffbass]

Here is the current look of the component side of the PCB.
I will try the audio probe to identify the source of the issue.
As suggested, the solder side is heavily masked by pots.
Thanks for your suggestions.
I really value the input.
This was my first component purchase build. So I bought the components from Tayda rather than getting them supplied with a kit.
I’ve learned a lot since placing the order. I ordered some solder lug input jacks for the expression pedal inputs but they didn’t fit in the space I had left myself with the artwork for the holes.

 

[leadfoot]

Any reason you didn't solder the s-sn connections on the right?

 

[proffbass]

Any reason you didn't solder the s-sn connections on the right?

The offboard wiring diagram only asked for 2 connections to that expression pedal output.

Here is a screenshot,

 

[leadfoot]

The offboard wiring diagram only asked for 2 connections to that expression pedal output.

Here is a screenshot,

View attachment 105329

Ok, cool. Totally misremembered the build doc.