welp...got my very first DIY pedal debacle!! Yippee! could use a little help--

[plexi12000]

hey dudes-  i put together a tube screamer 808. got the board from the GGG boys......

symptom:  No sound w/ effect on. (can hear a tiny bit if you dime the volume).  bypass mode....got sound.  battery is good....9.85 v   Wired ok. (but will check again, because i'm a freak)

Mods: I used two bs170's for extra clipper mod.  And tried Aron's mod....removed the .22uf at bottom of board (put a length of wire between the holes) and increased the other .047 to a .47 uf.

I have voltages at all IC pins, EXCEPT pin 5....non invert input 2.  I think thats bad, right?

I have DC voltage at both sides of the 914 diodes. (is that right??)  DC volatge at ALL transistor pins- 170's and 2n4401's

Not sure how to trace "back" through the circuit.....any help and i'll send a hooker to your place.  thanks!  T

[Beo]

Audio probe my friend. Schematics work from left to right... somewhere the audio is getting stomped. Then you can focus your search.
http://www.diystompboxes.com/pedals/debug.html

[CodeMonk]

Pin 4 is ground so you shouldn't be getting anything there.

[antonis]

Mods: I used two bs170's for extra clipper mod.

Maybe something wrong with the wiring...
(did you wire them as Mosfets or as "body diode" style..??)

[Thecomedian]

This is why I should make notes.

The last time I had this issue, where you had no sound (possibly ticking or humming) between 0 to 99%, and at 100% you got some sound, it had to do with backwards wiring in the volume control or output.

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

[duck_arse]

erm, any chance of you telling us what the voltages actually are?

if you short the 220nF tone cap, [C9 on the ITS8 ggg schem] you'll cause havoc with the bias of IC1B

if you short the 220nF cap [C5 on the ITS8 ggg], you'll wreck the bias etc as above. lift that link; send hookers.

[plexi12000]

duck_arse.....  you think thats what it is??  my stupid pc. of buss wire?  if you remove the cap, you still need a path for elec. flow, dont you?  or am i missing something entirely?

[duck_arse]

plexi, the 220nF cap will be very selective of the frequencies it shunts to ground, and have NO effect on the stage bias. your bit'o wire has no such pickiness about it. it will shunt all the AC to ground, with the added bonus of taking all the biasing DC to ground as well.

[Thecomedian]

I read that it was Aron's mod to remove that cap. I'm kind of interested in this as well.

[duck_arse]

I just had a look at the ggg mods page for this, and it says "link" C5. seeing as one end connects to ground, and the other to the output of IC1A via R8, this mod will kill your signal.

remove cap ok, but don't link across, leave it mt.

[plexi12000]

DUCK_ARSE..........    I OWE YUOU A BIG THANK YOU!!!!!!    thats what it was.  you nailed it.

Man......of all the bonehead mistakes!!!  i wasnt think straight... "capacitor"---  Ac and DC.    yeah, i get it!  DUH

As a man of my word.....the highly attractive, large breasted, hooker will arrive around 9pm tonight.  Her name is Bruce. She sounded very pleasant.  hehehahaha

Seriously.....THANK YOU SO MUCH. i really appreciate it.

Thecomedian........  the Aron Nelson's mod is EXCELLENT.  my favorite 808...has just been supplanted by this one!!!  seriously.  a little bit bigger, bolder low end. still tight.

GREAT clarity..... now, i used some top secret capacitors in this one....that PERHAPS contributed to this clarity....but not sure because its the first time i ever used these in a circuit. so cant say for sure.

also using asymetrical clipping -extra 914.  still sounds better to me....than BS170's clipping.  but 170's, by no means, "suck"!  in fact,i think they sound better than a couple LED's that i've messed with.

so yeah....it's a GREAT mod.  Do it!  you'll prolly dig it.

[duck_arse]

nice work, plexi. we'll have to get on to aron, tell him someone at ggg is giving him a bad rep.

I liked that description right up to "Bruce". and, um, it's already 22:25 ......



.... I'd better go and turn on the light on the front verandah.

[plexi12000]

hahaaha!!  bruce was a no-show?!  damn him!

[duck_arse]

well, now, there was a bloke there tonight, but he had a stage-box under his arm.