Sunking Trouble ! Help please !

[Jimihendrix1987]

Hi there !

Yesterday I finished another sunking. I've built another two also (1 for my pedal rig, 1 for recording)... This is my third sunking.

But I'm in troubles now... This one sounds like shit, and there's no sound without the effect... I've tested the DV voltages at every IC and I've got several wrong values. With a 8.82v battery this is what I get:
             IC1          IC2          IC3
Pin 1   1.37          -6.70       8.69         
Pin 2   1.37          0             4.32
Pîn 3   0.93          0             0
Pin 4   0               -8.29       -4.11
Pin 5   0               0             -8.30
Pin 6   1.43          0             4.11
Pin 7   7.98          4.15          3.56         
Pin 8   8.65          15.13          8.67

You can see the wrong values in red. On my first switch on I realized I put c10 backwards !! ... Then I changed it, but I got no improvement... I have also change every IC, and almost CAP... I've checked every resistor and they are allright...

I'm going mad !! Anyone could help me? Any ideas?

PD --> On my third switch on, when I have rechecked all ... One component board (i don't know which) begun to smoke!

[madbean]

I would check to see that you are getting the correct bias voltage throughout the circuit. Remove IC1 and IC2. Confirm that R25, R26 are both 27k and that their junction point produces approx. 4.5v. Next confirm that R3 is 1M. Check pins 3 and 5 of the sockets (or pads) on IC1 and take voltage readings there. What do you get?

A smoking component would indicate incorrect voltage going someplace it shouldn't or possibly a backwards diode.

[Jimihendrix1987]

Ei Brian 

Ok, I've done everything... Here are the results  :

R25 and R26 are both 27k... I've tested the voltage but i'm sure i have done something wrong ... because i get 0v !

My R3 is 100k not 1M (you say 100k in your layout, and the 2 other sunking i've built were exactly the same) ... Pin 3 and 5 = 0v each other... There's no voltage there !

What have i done wrong doctor? ... The diodes are all soldered in the right direction ! ...

... My CPAZ has blown away right now !! It's smoking

[madbean]

Sorry, I meant R2 as 1M, not R3.

Can we have a pic of the top and bottom of the build?

[Jimihendrix1987]

Yes, of course !



R2 is 1M ... I've re-checked every resistor and cap... I can't find where the problem is ! ... Now I know that my CPAZ was smoking because when I was checking the voltages in it, I join pin 1 and 2 with my multimeter tip !!

But now the readings in there are allright... Except pin 7, where i get 3.55 (with a 8.5v battery) instead of something next to 5v !

Do you think my CPAZ has recovered from its dying?

Thanks Brian !

[Jimihendrix1987]

Hi there Boys !

I have just solved it, however I still don't know what the problem was. Finally I keep on desoldering items to begin again. By the time I finished it my brother was already prepared to play it And then, It Worked !!

Hurray !!  

It sounds incredibly awesome with replacing he treble cap with a 6.8nf one ! What a pedal !

[bigmufffuzzwizz]

Hi there Boys !

I have just solved it, however I still don't know what the problem was. Finally I keep on desoldering items to begin again. By the time I finished it my brother was already prepared to play it And then, It Worked !!

Hurray !!  

It sounds incredibly awesome with replacing he treble cap with a 6.8nf one ! What a pedal !

Thats awesome!! I'm gonna have to try some of the suggested modifications when I finally get around to building mine. There's quite a few now!

[madbean]

Good to hear that it is working. I really need to try out this treble cap mod myself. I have a build that's been collecting dust...just waiting to be boxed.

[Jimihendrix1987]

Come on Brian ! I advise you to Replace it ! You are going to love the softer sound it gives at full tone ! Not more edgy sounds with the strat