volume pot issues

[ninjadave7]

i just built a drive using this layout - http://freestompboxes.org/download/file.php?id=1606&mode=view

i know it's on a different forum, but thought i'd ask a question here too.

when i first wired it up the volume pot increased volume to a point then quickly got softer and then nothing.  i realized that the vol 1 and 3 wires are mislabeled in the layout and should be reversed so i did that.  now at zero the signal cuts completely and as i increase it gets loudest at around noon and then decreases in volume till it's at about 50%. 

i've tried different pots just to be sure i didn't have a hardware problem, but same issue occurs, so i think it's either a layout or wiring mishap. 

any suggestions?

[KazooMan]

Your link got messed up during posting.  Give it another try.

[ninjadave7]

thanks, i didn't catch that...

http://freestompboxes.org/download/file.php?id=1606&mode=view

[R.G.]

when i first wired it up the volume pot increased volume to a point then quickly got softer and then nothing.  i realized that the vol 1 and 3 wires are mislabeled in the layout and should be reversed so i did that.  now at zero the signal cuts completely and as i increase it gets loudest at around noon and then decreases in volume till it's at about 50%. 

I have not looked at the link and so on, but what you describe is what would happen if you had the wires to the pot still messed up.

Do this: Get out your ohmmeter and using it on the pins of the pot, find out what pin is the wiper, and from that, which is the cold pin (that is, the pin the wiper connects to when turned fully counterclockwise) and the hot pin (that is, the pin which the wiper connects to when turned fully clockwise). From that, you can connect the wires correctly. Numbering pot leads has always been an issue with me, because manufacturers don't do it consistently, and the various informal guides get it both different ways. So I always refer to Hot (clockwise), Cold (counterclockwise) and Wiper instead of 1, 2, and 3.

[KazooMan]

It looks like this forum doesn't like to include the name of the other forum in your url, replacing it with a string of dots.  Entering the other forum name into the browser by hand works.  Now perhaps someone can offer a suggestion.  

Have you double-checked your layout of the components, their values, orientation of the diodes, caps, and the IC, and the four cuts in the stripboard where indicated?

[KazooMan]

After reading R.G.'s reply, I had a look at the layout at "that other forum".  Interesting. They actually DO have leads for the volume pot labeled "to vol 1" and "to vol 3" with nothing for the wiper.  I see the input, but where is the output?  Does it come off the vol pot?  Is there a schematic?

Edit:  I found the schematic and indeed, the wiper is the output. 

[ninjadave7]

the wiper is the output.  checking the pot now with a meter how RG suggested, but since volume goes off completely at fully counterclockwise it seems like the wiring is right.  obviously it or something else is not though.

[Paul Marossy]

Edit:  I found the schematic and indeed, the wiper is the output. 

That's kind of a given, you're supposed to know that. But you wouldn't if you are just starting out with this stuff. 

[ninjadave7]

ok, checked the pot with the ohm meter.  i had subbed a 100k pot instead of 500k in process of trying to solve the problem, so counterclockwise all the way was 91k between wiper (middle when facing me and right side up) and ground (left), 2 ohm between wiper and hot (right).  all the way clockwise was 91k between wiper and hot, 2 ohm between wiper and ground.  i think that's normal, but wouldn't be surprised if what i think is right isnt...

any more ideas?  volume goes from 0 to 10 in the first half of the sweep, then back down half way?

[KazooMan]

[

That's kind of a given, you're supposed to know that. But you wouldn't if you are just starting out with this stuff. 

  Well, of the 22 drive/distortion projects listed at the GGG site the only one I have ever built is the tubescreamer.  You might want to review the schematic for that one.  There is a whole pantload of stuff downstream of the volume pot wiper.   

[ninjadave7]

any other ideas?  volume peaks and then goes back down?  i checked against the schematic here -

http://i239.photobucket.com/albums/ff314/lovepedaldetective/LovepedalBurstEternitySchematic.gif

everything on the layout matches, not sure how to proceed troubleshooting... help?