Colorsound Overdriver not Working

[Ofek Deitch]

Hi guys,

I finished a few hours ago a clone of the Colorsound Overdriver, and when I fired it up there was only weak signal. after messin' with it a bit I found out that when I tilt the circuit board a bit the sound suddenly comes back.
The pedal is true bypass, and only the effect isn't working. nothing is changed when the effect is off - so I figured there was a bad soldering joint or some thing and started reheating some who looked bad.
But then, when I tried it again there was no sound.  

I don't know why, but when I touch with my thumb +9v on board and Q1's Base I get signal again (with effect).


Here are a few pix:





and this is the layout I'm using



Thanks for any help!
Ofek  

[GibsonGM]

Go thru this, and post us some info...

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

[Ofek Deitch]

This is the schematic I used to make the layout from:



The layout has been verified by the two other builds I made in the past.

All knobs used to work until I messed something in the circuit board, and now there's no signal when effect is on.

Voltages are:
Q1:
C 0.7v
B 0v
E 0.15v

Q2:
C 0.13v
B 0.7v
E 0v

Q3:
C 5.76v
B 1.44v
E 0.84v

Dont know if this is important, but all knobs were all the way up when I measured the voltages.

[R.G.]

I finished a few hours ago a clone of the Colorsound Overdriver, and when I fired it up there was only weak signal. after messin' with it a bit I found out that when I tilt the circuit board a bit the sound suddenly comes back.
The pedal is true bypass, and only the effect isn't working. nothing is changed when the effect is off - so I figured there was a bad soldering joint or some thing and started reheating some who looked bad.
But then, when I tried it again there was no sound.  

I don't know why, but when I touch with my thumb +9v on board and Q1's Base I get signal again (with effect).

You already know what's wrong - there's a bad contact somewhere. It's just a matter of running it down. You've almost located it already - Q1 is not pulling enough current to keep Q2 in the linear range, and when you turn it on a bit with your thumb, things work.

Go find why Q1's base isn't biased correctly. From the voltages, Q1 base looks open or shorted to ground.

[Ofek Deitch]

Found it!
The legs of the 25uf Electro Cap to ground next to Q2 are shorting each other!~

Everything works now!
I actually find the error in the picture I uploaded to this thread. Much bigger and clearer..

[Electric Warrior]

The cap across the bass pot is missing in the schematic you used..

[Ofek Deitch]

what value is it? .1uf? nf or pf?

[Hemmel]

.1 with no other indication usually means .1µF, or 100nF.

[Davelectro]

Everything works now!

Great. How does it sound?

I really like this circuit. Excellent clean boost and magnificent fuzz. The problem seems to be in the overdrive region, which is kinda splatty no matter how close to 5V you get through biasing.

Maybe it doesn't like humbuckers. I don't know.

[Ofek Deitch]

I love it! It is, with no doubt, one of the best pedals I've had a chance to make/play with !
I like to use an Anti-Log pot for the Gain (10k) instead of a Linear one - really gives a lot more control over your tone 

[GibsonGM]

Glad you found the problem ) 

[Lurco]

Everything works now!

Great. How does it sound?

I really like this circuit. Excellent clean boost and magnificent fuzz. The problem seems to be in the overdrive region, which is kinda splatty no matter how close to 5V you get through biasing.

Maybe it doesn't like humbuckers. I don't know.

With or without that cap across the bass pot?

[Davelectro]

With cap across the bass pot, of course. Just like in the original.

No doubt the splattiness is related to biasing. In fact this is a known issue with this circuit.