Bypass... am I stupid?

eleanor296 · July 28, 2008, 05:08:37 PM

hey guys,
finally got around to building my first "from scratch" pedal, and tried Tim Escobedo's Uglyface.
The link below shows you guys some pics

http://s20.photobucket.com/albums/b206/eleanor296/uglyface/

my problem is that... it doesn't work

But I just can't figure out why.
The status LED works, but I don't get sound no matter if bypassed or engaged.

So... either the jacks or the switch are wired wrong. But I can't figure out what I did wrong.
I used the switching arrangement from the beavis audio site (thanks):
http://www.beavisaudio.com/techpages/StompboxWiring/

Thanks for taking a look guys!

~Andy

F.V · July 28, 2008, 05:19:31 PM

I cant recommend enough making an audio probe and testing the pedal with that, schematic and diagram by your side, its a really intuitive way of finding out what's wrong, and you'll be able to find the problem a lot sooner than just stabbing in the dark with it, and if a components gone then it'll be easier to find. It's also neat hearing what different parts of the circuit are doing. Use a headphone amp though helps not to annoy your significant other or family...

eleanor296 · July 28, 2008, 05:23:00 PM

well, shouldn't my problem be solely based on my jack and 3dpt wiring? After all I'm not getting sound during bypass either.

I'm using the ground from the sensitivity pot to ground both jacks.... is that a problem?

~Andy

eleanor296 · July 28, 2008, 05:32:24 PM

ooops... I forgot... I'm using Jan Carreman's layout (thanks again!):
http://www.aronnelson.com/gallery/main.php/v/album171/UglyFace.gif.html
Or, at least, it's pretty close to this one... with addition of a 2.2k current limiting resistor for the LED, and it's a little "wider" in some places due to bigger board size.

~Andy

mdh · July 28, 2008, 05:41:43 PM

Well, it looks like at the very least you probably have the terminals of your output jack swapped. It appears that you have the tip of the output jack connected to the sleeve (ground) of the input jack, and the output from the bypass switch wired to the sleeve of your output jack. I'm certainly not claiming that's all that's wrong, but it would be a good place to start.

eleanor296 · July 28, 2008, 05:50:33 PM

Quote from: mdh on July 28, 2008, 05:41:43 PM
Well, it looks like at the very least you probably have the terminals of your output jack swapped. It appears that you have the tip of the output jack connected to the sleeve (ground) of the input jack, and the output from the bypass switch wired to the sleeve of your output jack. I'm certainly not claiming that's all that's wrong, but it would be a good place to start.

That's what I thought at first too...
they're switchcraft jacks, but weirdly arranged.... I've already tried reversing them. Didn't do anything. There might of course be more that's wrong, but... hmmm. The jack should be right. The sleeve is the one with the purple wire (yeah.. weird... I know... but that's exactly what it looks like.). Weird huh? I'll reverse'em again and tinker around some more.

~Andy

MikeH · July 28, 2008, 06:04:22 PM

The ring (ground) of your input jack is connected to the outside (tip) of your output jack. And the switch (output) is connected to the ring (ground) of your output jack. He's right; you need to reverse them. For starters...

eleanor296 · July 28, 2008, 06:05:13 PM

Quote from: eleanor296 on July 28, 2008, 05:50:33 PM
Quote from: mdh on July 28, 2008, 05:41:43 PM
Well, it looks like at the very least you probably have the terminals of your output jack swapped. It appears that you have the tip of the output jack connected to the sleeve (ground) of the input jack, and the output from the bypass switch wired to the sleeve of your output jack. I'm certainly not claiming that's all that's wrong, but it would be a good place to start.

I switched'em around... and it works! Kinda... output VERY low, and frequency bleedthrough on bypass.
I'll go search for other thread where someone might have had the same issues.

petemoore · July 28, 2008, 06:20:04 PM

DMM, and the jack + anything that could go with it [such as a cable.
For a stereo jack, the lug assignments can be varied, the ring and sleeve connect when a 1/4'' phono plug is in it.
For a DC jack, it also can have a switch in it, the DC plug insertion is what activates it.
Putting a plug in the input jack, and clipping one DMM lead to the tip, then tracing to the lug, through lug to switch, through switch input to switch output lug [check lug assignments here]...you should get continuity between the input cable tip and the first thing on the circuitboard [such as input cap or resistor].
The output can be traced through the same way.
A 3PDT can be installed 1/4 turn 'wrong' [say you have switch in your hand with lugs facing you, turn 1/4 turn to 'correct' or 'incorrect' orientation...I like to have the right middle lug be the input, the right top lug the bypass, and the right bottom lug to circuit input. Testing that the right and left side of the switch switches the middle lugs to the top Or bottom lugs [right middle to right top or bottom // left middle lug to left top or bottom]...because the signal switching will not work with a switch turned 1/4 turn too many or not enough...to make it work the whole switch may need unwired, turned 1/4 turn, rewired.
One jack not grounded, or one ground too many [say grounded signal] will also defunct it.

eleanor296 · July 28, 2008, 06:46:43 PM

ok, so,
bypass is working fine now.
Still very low volume (VERY VERY low), I noticed that I'm only getting around 4V on pin 5 of the 386, but I'm supposed to get 9, right?

Don't have an audio probe yet.. I'll build one soon.

The switch is installed right. I checked continuity on it. Jacks to their respective input/output points on the perfboard check for continuity.
Thanks for the help so far

tiges_ tendres · July 28, 2008, 07:29:09 PM

if the output is low, there is definitely a problem! this thing is ULTRA loud!

Check your volume pot wiring, and post some more voltages

eleanor296 · July 28, 2008, 08:29:15 PM

ok, here we go:

JRC386D:
1: 1.28
2: 0
3: 0
4: 0
5: 3.99
6: 9.00
7: 4.40
8: 1.28

CMOS 555:

1: 0
2: 4.50
3: 4.50
4: 2.91
5: 5.97
6: 4.50
7: 0
8: 9.00

Everything looks about right?

petemoore · July 28, 2008, 09:54:21 PM

JRC386D:
1: 1.28
2: 0 I don't have the data sheet for the 386, but from memory, this pin
3: 0 Or pin 3 here is input...check data sheet, find input pin, check bias to have room to swing +/-
4: 0
5: 3.99
6: 9.00
7: 4.40
8: 1.28
And not sure what pins 7 and 8 should read.
CMOS 555:

1: 0
2: 4.50
3: 4.50 Although this looks good...
4: 2.91 Isn't pin four assigned as Gnd. pin on 386 ?...ie should be 0.00 Vdc .
5: 5.97
6: 4.50
7: 0
8: 9.00 Now there's 9v on pin 8 instad of pin 6, and this is the same circuit board ?
I suspect one of these sets of #'s is a misread or typo..

eleanor296 · July 28, 2008, 10:50:05 PM

Quote from: petemoore on July 28, 2008, 09:54:21 PM
JRC386D:
1: 1.28
2: 0 I don't have the data sheet for the 386, but from memory, this pin
3: 0 Or pin 3 here is input...check data sheet, find input pin, check bias to have room to swing +/-
4: 0
5: 3.99
6: 9.00
7: 4.40
8: 1.28
And not sure what pins 7 and 8 should read.
CMOS 555:

1: 0
2: 4.50
3: 4.50 Although this looks good...
4: 2.91 Isn't pin four assigned as Gnd. pin on 386 ?...ie should be 0.00 Vdc .
5: 5.97
6: 4.50
7: 0
8: 9.00 Now there's 9v on pin 8 instad of pin 6, and this is the same circuit board ?
I suspect one of these sets of #'s is a misread or typo..

386:
Pin 3 is input. What do you mean "find input pin, check bias to have room to swing +/-"?
Pin 7: Isn't connected to anything.... should I actually get a reading on it then?
Pin 8: Connected to Pin 1, same reading, so I'm good there.

555:
Yes, Pin 4 is grounding pin on the 386, but pin 1 is grounding pin on the timer IC. If you meant pin 4 on the 555, it's connected to the threshold pot and the 2.2uf cap connecting it to pin 5 of the 386.
9V on pin 8 is right, I don't know how I got 9V on pin 6 the first time... sorry.

eleanor296 · July 29, 2008, 06:12:12 PM

anybody?
Thanks!

eleanor296 · July 30, 2008, 03:05:09 PM

ok, so I'm getting a signal on both pin 4 of the 555 and pin 5 of the 386... don't know how loud the signal on pin 5 of the 386 is supposed to be, but it's about as loud as it's on the 555.

~Andy

eleanor296 · July 31, 2008, 01:27:46 PM

I reflowed a couple solder joints that might have been cold, and now it works.
At least the effect does.
But, I'm now getting an obnoxious loud hum/buzz as soon as both power and the input jack are plugged in.
Grounding issue, right?
Well... I reflowed every ground connection. Still nothing.
Arrrgh this thing is driving me crazy.
Also, first pedal that didn't fire up initially... and that's after 3 tube screamers (2 for friends), a Tripple Fuzz and a wah.

Any tips would be appreciated
Thanks for reading!

~Andy

JDoyle · July 31, 2008, 01:43:56 PM

Quote from: eleanor296 on July 31, 2008, 01:27:46 PM
I reflowed a couple solder joints that might have been cold, and now it works.
At least the effect does.
But, I'm now getting an obnoxious loud hum/buzz as soon as both power and the input jack are plugged in.
Grounding issue, right?

Sounds like a ground loop to me. Did you link any of the input jack ground connections together and THEN to ground? In other words did you take the ground connection of the output jack, connect it to the ground connection of the input jack and then from that point connect a wire to the ground plane? Same goes for the power jack.

Every ground connection needs to have its own path directly to the ground plane. You can get away with not doing this with a lot of effects without a lot of problems, but if you have a 555 in there, you have a lot of hi freq 'hash' coming off of each of the square waves the 555 produces. This makes the grounding very important as well as sensitive. It also makes a ground loop the perfect antenna to pick up that 'hash' and inject it into the signal path.

You have to be really careful about grounding when you use a 555, or anything that outputs square waves.

Regards,

Jay Doyle

eleanor296 · July 31, 2008, 01:46:23 PM

oh, so that IS the problem.
Yeah, in an earlier post I stated that I connected the input and output jack grounds.
I'll re-do the grounding scheme and report back.

Thanks a lot, JDoyle! I didn't know I couldn't do that.

~Andy

JDoyle · July 31, 2008, 01:54:14 PM

Quote from: eleanor296 on July 31, 2008, 01:46:23 PM
oh, so that IS the problem.
Yeah, in an earlier post I stated that I connected the input and output jack grounds.
I'll re-do the grounding scheme and report back.

Thanks a lot, JDoyle! I didn't know I couldn't do that.

~Andy

Andy, like I said, you CAN do that and get away with it in a lot of cases. God knows I have.

But with a 555, everything gets touchy.

I apologize, I just read your last post as I thought the original problem had been fixed...

Regards,

Jay Doyle

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Bypass... am I stupid?