Escobedo Uglyface issues

[fifteenrabbits]

alright. I had this thing working beautifully. I played my guitar through it for a couple hours, and then I tried my bass. after about 10 minutes of bass playing it cut out. I don't know if the two are related.

Now, I probed the circuit a little bit and found out that the 386 is still working, but the 555 didn't seem to be doing much. and then I mistakenly bridged two legs of the 555 and it smoked. I decided to install IC sockets and replace the ICs and see if that works.

Now I did that. Still does the same thing. Very low output, no oscillations, no envelope follower, very little effect from the controls.

I checked it out and the 555 is hot as hell.

Any idea what might be going on??

For those of you who don't know the circuit...

http://www.experimentalistsanonymous.com/diy/Schematics/Fuzz%20and%20Fuzzy%20Noisemakers/Uglyface.gif

[glops]

Are you using the same type of 555 chip?  I used a CMOS 555 from Radio Shack for my build.   I don't have a solution for you but something about your post seems familiar in regard to that circuit.  Have you tried the search function here?  Did you put this down on perf or is it on a breadboard?  I always breadboard everything first to make sure it works well.   It's a cool circuit.  The one I made has some different part values than the schematic and is definitely missing something.  Need to pull it out and do some tweaking some day.... 

[fifteenrabbits]

Yeah, I used the CMOS 555...


The thing worked goddamn perfectly before I plugged my bass in!


damn. I suppose I'm going to start troubleshooting my first circuit soon.

I suppose if nobody can help me with specifics about the circuit maybe somebody can give me some pointers on troubleshooting or link me to a good page about it?


Thanks,
Rabs

[soggybag]

Not sure tat your bass is the problem. I have built a few of these and they are all durable. Though I have burned up a few 555s. Not sure what does this. But the chip gets hot and that's it.

[1878]

Try the vactrol. I had this thing built perfectly (but not working) before I realised the two manufactured vactrols I'd bought were the problem. I built my own vactrol and it worked perfectly. I wouldn't have a clue if a bass would blow a vactrol, but 'Very low output, no oscillations, no envelope follower, very little effect from the controls' sounds like my Uglyface build before the homemade vactrol was installed.

Vactrol 

[fifteenrabbits]

Hm. Wow. Nice to have responses. I've been doing this stuff for maybe a half of a year and this is my first real forum post.

Well, I'm looking at datasheets for the timer. and I'm trying to find a datasheet for the 386. (the internet is throwing me around like a basketball for this! I'm about to grab it from mouser)

Trying to figure out how the circuit works. I'm about to rebuild it. This time with standoffs from the case for better heat dissipation and to lessen the likelihood of a short against the enclosure.

I have a feeling that the optoisolator isn't the issue. Mine actually was homemade, but I don't think that that should matter. I'll test it again in just a bit. My vague (and possibly premature) understanding was that the optoisolator was part of an envelope follower in the circuit, and thusly, the circuit should be able to self oscillate without it. I'll test the optoisolator now and make sure, though.

Thanks a bunch! Still working on it!
Rabs

[glops]

Is the Ugly Face your first one?  I would have been at a loss if it was my first.   But it was my second!

My advice is to bread board the circuit and get it working and then solder it to perf/vero/etc.  

If it was working before though, maybe you messed a trace when desoldering the 555?  Check your soldered connections near those points
of the socket, make sure the 555 is installed the right way in the socket....

[fifteenrabbits]

Nah, its not my first.

I actually breadboarded it and it didn't work correctly. The escobedo schematic is a little messy to me and so I figured I would just go ahead and build it from a layout.

I used this:
http://www.home-wrecker.com/uglyface.html

I also used his .001 caps on the input and output. Only, though, I used three smaller caps to get the right capacitance. I'm thinking maybe I blew one or more of those?

Like I said, I put the thing back together with sockets. I did double and triple check my work so a backwards chip or missing connection shouldn't be the problem.

Rabs

[fifteenrabbits]

Hey 1878! forgive me for my doubts! the led on the optoisolator was dead. I'm still going to entirely rebuild the thing more cleanly though!


I'll keep y'all updated.

[1878]

No probs at all. The Uglyface was my first build and I learned quite a bit (mainly by my own mistakes !!) whilst doing it.

[fifteenrabbits]

Alright! second uglyface I got working correctly that ended up the same way!

once again, the 555 is steaming hot and the controls don't do anything.

This was an entirely new build. Maybe something is wrong with the layout?

This time I had the thing debugged and working for only about 5 seconds before it cut out to a low volume and the controls became largely useless. This time I was running a small casio into it.

I really think it just hates something about strong signals, maybe I should cut the gain on the 386 and throw a new 555 in there?

-Rabs

[soggybag]

I've built more than a few of these, and people on the forum have been building this for years. There is nothing wrong with the 386. This works fine.

There is probably an error in either your PCB or your wiring. I have had a similar trouble in the past. I don't remember exactly what was the culprit. But the symptoms were the same, hot 555, then nothing. In your next build put your finger on the 555 right after power up and see if it's getting hot, before playing. If so power down and find the problem.

Check the wiring around the frequency and threshold pots. If one these was wired wrong you might send too much juice through the wrong pin. Remember the Threshold pot connects to +9v through a resistor. If this resistor is not there you could have problem.

The same goes for the frequency pot. This is connected to +9v through that 100k resistor. If this resistor were jumped you'd 9v going into pin 7 and pin 3.

When testing if you fire things up and there is no heat at the 555, try moving the Threshold pot to either extreme and check the 555. Try it again for the Frequency pot.

[fifteenrabbits]

Might removing the power diode have anything to do with this?

That seems to be the only thing that differs my circuit from the schematic. My resistors and pots are wired up correctly.


Thanks,
Rabs

[1878]

Not too sure on the power diode, but I think it's there as polarity protection. I included it in my build & I've never had any problems with either of the chips etc.

[fifteenrabbits]

So I'm thinking of beefing up those resistors a little bit to see if that will help. I suppose I'm going to go ahead and do it.

If anybody has any better ideas, shoot em to me.

Rabsy

[1878]

It seems that something, somewhere is letting too much power get to the 555. Are you still using sockets ?? Maybe too much heat from the iron is weakening the chip before you start. What is the chips power rating ?? Get a couple of different 555's and see what happens. Easy if you've socketed.

Hope you get it sorted. I know how frustrating this can get, and how much fun you can have when you've cracked it !!

[fifteenrabbits]

I actually checked without a chip in the socket, what the voltage relation to ground was on all of the pins.

A lot of it seemed way high, would the chip being in there make a difference?

Should I be checking in relationship to some other point than ground?

[fifteenrabbits]

nobody? nothing?

...,
Rabs