OMG Mongoose Oscillation

[Jason Thomson]

G’day Troops, I’ve got a OMG Mongoose build here that gets an oscillation going when pushing the Sensitivity & Fuzz controls up reasonably high. I’ve had this built for quite a while and had actually sold it but upon final testing before shipping, I found that it oscillates. Subsequently, having to cancel the order. I don’t have the build doc any more and I can’t find it online, so can’t check my part values.

Here are the OPAMP voltages:

Vin- 9.44v. P1- 4.78v, P2- 4.80v, P3- 4.55v, P4- 0.00v, P5- 4.78v, P6- 4.77v, P7- 4.76v, P8- 9.43v

Board pics below.

Cheers,

Thommo.

[Billy]

Here’s V3 build doc

https://drive.google.com/file/d/1WqKQNCBHqxn6tkN-b-mtZ7fskTb68koH/view?usp=drivesdk

Idk if increasing R6 may solve it yours looks like 100R instead of 220R did you try it with battery only power or to try and find the cause try tapping your finger on and off the solder joints to see if it affects the oscillation

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