Ugly face oscillation

[Radamus]

Hello. I just "finished" my ugly face a couple of hours ago and I have a problem that I have had once before. When I originally built the PWM, I knew nothing about sockets, so I soldered the IC's, one of them the 386, to the board. I think I fried one and wound up with some serious oscillation, even at the guitar jack. I eventually built another one with a socket and it worked brilliantly. But now I'm on the ugly face and I have the same problem. Both Ic's were socketed and should not have come into any contact with heat.

When I audio probe, I get nothing to work with as the oscillation is quite strong before the LM386, and remains so throughout the circuit. When I alter the frequency knob, I get a pretty good range of pitches with the oscillation, but I can't get any guitar signal in there.

I checked the voltages, and I don't remember them all, but the connections directly to hot were in the 7.8 region (old battery, problem persisted with a new battery as well). The other pins were usually around 2v and pin 7 of the 555 was 3.6 or so. I think that's about where they all should be. I rechecked my wiring and it's all correct as far as I can tell. I used a 4066 for switching, and it works in bypass. I have a lot of jumper wires as I had to make room for the 4066, making the rest of the layout rectangular, rather than the square layout from Jan Carremans. The optocoupler is homemade, in the same way I made the ones in my McMeat, and they work just fine.

The unit is not in a box as of yet. I usually don't put them in any enclosure until after I make sure they work.

I know a lot of oscillation issues have to do with grounding, so I'll probably check out my ground section tomorow, taking all of the IC's out first.

What could be causing my oscillation here? I know the circuits supposed to do it, but I couldn't find any setting where it didn't do it.

Thanks in advance

[Radamus]

I found that some of my grounds were not completely connected for whatever reason and I did my best to fix that. I took the 386 and the 555 out, but I left the 4066 in, thinking it was too far away. I think I cooked it (whenever I connected the battery and then touched it, it burned my fingers), so I replaced it. My problems are now a little more complicated.

There is still a lot of oscillation, but there are settings for each pot where I can get some use, but when I stop playing, there is oscillation again.
The other issue is that I'm not getting clean bypass anymore. I checked the voltages all over the 4066. The V+ part is 8.7v and the two control pins for that side of the switch are also 8.7 or thereabouts. A couple of other pins are 1v or less. I have these parts hooked up to a DPDT (just seemed easier than millennium bypass).  When I use the DMM to tell me if things are connected, I run into some trouble. The circuit input is never within the "beep" region of resistance to any of the other pins on the 4066, making me think that it's internal resistance is a lot bigger than I thought.
Also, I have the DPDT (one side of it) connected to hot in the middle, with the two other sides each going to a different control section. When there is no electricity in the circuit, the middle will connect to one other side, depending on pressing the stomp switch. When I connect the battery and put in an unconnected 1/4" plug, that also stays the same. When I plug in my bass and put the other end into the amp, then the side of the DPDT that is supposed to turn the effect on is always on, taking away my clean bypass.

I'll put down the voltages: Battery- 8.63v
386
1-1.24
2-0
3-wiggles between -.2 and .6
4-0
5- 4.68
6-7.96
7-3.96
8-1 to 1.3

555
1-0
2-4.07
3-4.07
4-7.93
5-5.31
6-4.06
7-0 to 2
8- 7.9

4066 (In bypass)
1- .54 to 1.5 Circuit input
2-same^ Input jack
3-^ Input jack
4-^ Bypass
5- 8.62 Off
6-8.6 Off
7-0 Ground
8- .54 to 1.5 Bypass
9-^ Out
10-^ Out
11-^ Circuit output
12-.8 On
13-.79 On
14-7.9 Hot

Pins 5 and 6 control whether 2 and 3 connect to 4, and whether 9 and 10 connect to 8. Pins 12 and 13 control whether 2 and 3 connect to 1, and whether 9 and 10 connect to 11. That's how I wire it up.

If there are any other voltages I can provide, please let me know.

[Radamus]

I really need some help here. This isn't making sense at all. I tried to audio probe again, but I'm getting oscillation at the input jack, which makes that impossible. Do I have a bad 386 chip? It's fresh from radio shack. No heat on it. Is it possible that my wires are causing it? When I move the audio probe close to the circuit, without touching anything, the noise is audible. It gets much louder when I make contact. And with the crazy noises this thing makes, my girlfriend couldn't even help me debug with the amount of completely ugly sound coming out. I turned the treble all the way down, too.

Anything could help, even if it's something rudimentary I might have missed or never learned. I'm mostly self-taught here, so feel free to treat me like I'm stupid.

Thanks again.

[Radamus]

I waited a little while to let my frustration subside and get some homework done over the last few days. I went to play with it again and I ran into the same exact problem that I've been having. I tried removing each of the chips to see when the oscillation started and began. There was some present each time I removed a chip. I swapped them all out to make sure I hadn't destroyed any of them, except the 386 as it's my last one for now. Finally, as a last ditch effort, I thought I would scrap my 4066 switching and just put it on the DPDT. I had heard of a lot of people having trouble with input bleeding to output and a bunch of other things like that, so I thought that maybe the 4066 wasn't separated enough to keep the sound from bleeding. At any rate, I knew my bypass wasn't working, so I figured I would start there. I wired up the switch so that the circuit output was on the middle pin of the second half of the switch, so I could ground it if necessary, but it wasn't. Now the circuit works pretty well, but I think the 10k sensitivity pot is probably too small for me. Only the very last quarter of a turn is useful, and the decay takes forever. I'm using a passive bass, too. But at least now it works. I might have to figure out millennium bypass in the future, but I think I'll know when this effect is on based on the gnarly sound.

I hope this helps somebody out there. I'm still not sure what was wrong, but that's how I fixed it.