Proco Rat build, got some HF noise - [solved, wiring error]

[cassist]

Hello all, just "finished" my first build. I've got a bit of electronics background, mainly theoretical but not much in terms of pratical construction.
The pedal works, but with the distortion knob past a certain amount, rapid oscillations start occurring. Sounds similar to tuning the radio. At first I thought it was feedback from using long unshielded wires for input and output wiring, so I shortened them. The noise is quieter now, but still overpowering. I don't have any shielded wire to use, so buying that would be my last resort.

The schematic I used is the one from tonepad http://tonepad.com/project.asp?id=45. Some of my caps aren't the same physical size, but all the values are the same.

My next guess would be the wiring for the pots. All the wiring is done with old cat5 single core conductor, and for the pots I left the wires as twisted pairs. Could this be the cause of the noise?

Any help would be much appreciated!





Mike


-edit-

One thing I've noticed is that when I dial down (to 0) the tone pot on the guitar, the noise disappears. However, with the guitar unplugged the noise is the same as if the tone pot was at 10.

[R.G.]

1. Are the power supply bypass caps on the PCB?
2. Is the + input bypassed to ground with the indicated 0.001?
3. Try a 0.1uF ceramic cap from pin 8 to pin 4 directly across the IC pins.
4. If those don't help, it's likely to be a wiring problem, either from close proximity or a wiring error.

[cassist]

1. Are the power supply bypass caps on the PCB?
2. Is the + input bypassed to ground with the indicated 0.001?
3. Try a 0.1uF ceramic cap from pin 8 to pin 4 directly across the IC pins.
4. If those don't help, it's likely to be a wiring problem, either from close proximity or a wiring error.

As I was going through your list, I noticed that I had neglected to connect the 30pF capacitor between pins 1 & 8 on the op amp. They were connected to the board but I had not connected the pads to each other.

Thanks for the help!