Demo tape fuzz - no sound

[John R]

Mid-Fi Electronics Demo Tape fuzz
https://tagboardeffects.blogspot.com/2014/02/mid-fi-electronics-demo-tape-fuzz.html

Not producing any sound. I'm just clipping alligators to the input and volume 3 strips. My assumption is that the tone controls should not need to be hooked up for some signal to come through -- they're all just essentially set to 0. Is that not correct?

IC voltages:

9V battery: 10.79
1. 9.43
2. 9.06
3. 9.83
4. 11.09
5. 4.9
6. 0.0
7. 8.19
8. .03

Also, I only had tantalum 1u caps, so I had to take my best guess at the polarity. They're the three orange ones.
Top: top + / bottom -
Middle left: top - / bottom +
Bottom: top + / bottom -

Thanks for the help,

John

 

[rocket88]

Couple of things I notice.

1. Pin 4 is ground so you should have 0V not 11.09
2. The tone controls do need to be in place since without them there's no connection being made between those points, i.e. not having them connected you're breaking the circuit.
3. I see a lot of bridges going on.
4. Looks like your alligator clip is touching multiple tracks.
5. I see a lot of components that aren't completely soldered.

I would make sure you have no solder bridges between any of the tracks, reflow the solder to make sure the components are connected completely, and connect the tone pots and retest.

[John R]

Thanks for the super-fast reply! Finally had a chance to try your suggestions, and they worked! I think the trim connection was the crucial one -- when that grounds out, it's super loud and fuzzy (contrary to most control pots). I also noticed that I had the 4001 diode going to the top row instead of row 2.

thanks for the help! This one's taking me back to 4-track days...

john

[rocket88]

great to hear man. not sure how many builds you've got under your belt, but sometimes it's little things like that which prevent a build form working. '
here's what i do every time a build doesn't work:

1. check for transistor/ic orientation and that they're installed. ashamed to admit the number of times a build doesn't work only to realize that i didn't put in the transistors or ic.

2. run a knife through all the tracks to ensure no solder bridges.

3. check that my solder joints are all good,

4. if they look good i check continuity to ensure no cold joints

5. check component placement.

6. if none of that makes it work i walk away for a few, usually a day or so and comeback with a clear head and really examine the board and component and wire placement.

usually i get to step 3 and it's up and running. most of the time its a simple thing like a solder bridge or a transistor/ic not installed completely and seated with the occasional wire or component off by 1 row.

[Marbles]

I second the walking away bit. In my first builds I got so frustrated when stuff didn't work. Nowadays, I glance at most, and forget about it for the day, knowing that it'll be fine the next day.

Almost every error I had was solved cause of a clear head. Cup of coffee and check placement of every component (resistor, 2 blank holes, cap spanning 4 etc :D) works almost every time.

Great choice of build I must add. I love his overdrive for the gritty, garagy, velvet underground cleanish dirt. Absolutely love it.

[John R]

Thanks for the encouragement. I've done at least a dozen builds off the tagboardeffects site, and maybe 1/3 of them worked. Asking for help on the project pages there elicited crickets, so I guess this is the place to post! I'm looking forward to going back through them with fresh eyes to see what I can resurrect.

Rocket88, I checked out your facebook page -- looks like you're making some very cool pedals! I wish I was on the East coast to come check 'em out.

John

[rocket88]

Thanks man.

Yea posting for help with the layout is hard to get help cause it has to be caught before its pushed off the recently posted sidebar. Always better to post here for help.

If you need anything you can always shoot me an email.

[Beaker]

+1 on walking away and leaving a non-working build for a while. I usually leave it a couple of days if I don't spot an error immediately. I find that I just see what my brain is telling me I'm supposed to be seeing if you know what I mean. I can consistently overlook an error without registering that it's wrong.

Leaving it a couple of days means I stop seeing what I want to see, and the error just jumps out at me.