Help needed with debug before Christmas!

[Fred]

Hi.  Sorry to sound so newb, I should just go away and figure it out myself, but I need to get this sorted before Christmas as this was intended as a present.  

I've just attempted to build a Rocket Fuzz on stripboard.  I thought I'd finished but when I plugged it in for a test, I got sound, and even a very pleasing smooth distortion.  The only problem is that it's being marred by an extremely ugly high-pitched squealing, with it being worst nearing full drive.

I just wondered if this was a well trodden path and there was some obvious cause.

As a sidenote, it seems to vary if I change guitar, but that's probably to do with the ouput level of the respective guitars.  There doesn't seem to be a large 4m7 resistor to ground on the input as in most of my other pedals and it is suggested as an option at General Guitar gadgets (though quite difficult to find).  Could that be the problem?

Thanks in advance.

[puretube]

sounds like a layout/wiring problem...

check, that no part of the circuit output comes near to the input;

there are other possible reasons - someone will chime in here, soon hopefully...

[Fred]

Hi, still got the problem.  I've checked my wiring and it all looks fine.

Having listened around with the audio probe I've found that everything is fine after the first buffer transistor and fine going into the base of the second.  But when I pop the probe on the collector of the second transistor I notice the yucky distortion that culminates in squealing.  The squealing seems to take over as the note fades.

The voltages off the transistors seem to check out fine with the ones at generalguitargadgets except the collector of the third which is 4.9 as a pose to 6.8, but I'm presuming that's within acceptable boundaries, but maybe not?

Here's the schematic if it helps anyone:
http://www.diystompboxes.com/pedals/rocket.JPG

Thanks very much for any help, I've really gotta get this sorted with increasing urgency!  Thanks again.

[aron]

I would try shielding the input and output wires as a start. I bet it's oscillating due to layout.