Echo Base - self oscillating issue

[notid]

Hi guys,

After having 2 builds in a row with no issues, I've broken my winning streak. 

So I ordered Taylor's Echo base pcb and built it this last weekend. However, as of right now, it's not working correctly.

+ I hear the original signal just fine, then this weird self oscillating sound that doesn't sound like it's "based" off the the guitar signal.
+ The level pot doesn't work - doesn't do anything
+ 3 of the other pots all seem to affect the delay time. So it'll make that race car sound if I start messing with them.
+ It sounds the exact same, whether bypassed or not. However the led does seem to work correctly

Other info:
+ I used the mod for a footswitch for self oscillating feedback\
+ I also noticed my voltage regulator looks very different from the one that taylor posted in his echo base page. Mine is much bigger with a heatsink on it. The heatsink is towards the bottom of the board on mine.
+ I double checked the orientation of the ICs
+ I did not put the diodes in to help prevent distortion as I use humbuckers.

Any thoughts?

Thanks,
Bryce

[Taylor]

I think you probably have an issue with your feedback switch. Take it out and wire the pedal up normally, see if it works then. If so, you can add the switch back.

Basically, all of that sounds like the way it acts when feedback is above 100%. Since you added the switch for max feedback, I'm guessing there's an error with that wiring which is causing max feedback all the time.

[tombola]

One slight confusing thing w/ the feedback / dub madness switch. You do not need to remove the 20k resistor, just add the switch on top. I removed the 20k (as that's how the other mods work) and got either zero or insane feedback...

[Taylor]

One slight confusing thing w/ the feedback / dub madness switch. You do not need to remove the 20k resistor, just add the switch on top. I removed the 20k (as that's how the other mods work) and got either zero or insane feedback...

Thanks for that; I'll add a note in the PDF to point out that you shouldn't remove that resistor when doing the dub mod.

[slacker]

Sounds like you've got a 7805 regulator in the T0-220 size, they work fine, that's what I use. The heatsink should be on the side furthest from the opamp, which it sounds like yours is.

Sounds like Taylor's got it right, the problem is probably somewhere around the feedback pot.

[notid]

Great. Will try these ideas and let you know how it goes. I did leave the 20k resistor in place. I was torn about which way to go on that. Looks like I made the right choice.