Chimaera with no gain please help!

[JPGraphX]

Hi guys,

I've started a new thread because I wanted to start clean and fresh to help you guys to help me :p!

Here is my situation;

I built a Chimaera and have no gain (distortion) only a boost of volume. I replaced my diode, it is now 1N34A.

I measured IC voltage :

           IC1          IC2              IC3
1    +4.63V    +4.6V        +9.24V
2    +4.64V    +4.63V      +4.62V
3    +3.55V    +4.63V      0V
4    0V             -9.24V         -4.63V
5    +4.63V    +4.63V      -9.22V
6    +4.63V    +4.63V      +3.97V
7    +4.61V    +4.66V      +5.29V
8    +9.27V    +17.02V    +9.25V

Could it be a bad IC?

Thanks a lot!
JP

[JPGraphX]

I get an incredible tone and boost but no gain (distortion)  on my sound..

[Bill Mountain]

Do you have a schematic?

[JPGraphX]

Yeah sorry http://www.grindcustomsfx.com/forum/viewtopic.php?f=2&t=180

[midwayfair]

Do you have a schematic?

He can't post it.

JP, have you made an audio probe? I think it will help here. You can make one from an old patch cable and a capacitor. Then you can probe the circuit at the diodes and make sure that the gain section is working. There aren't really any parts in that section that are commonly mixed up.

Your voltages look fine.

Need a better description of what the gain knob does. When you rotate it clockwise, do any of the following happen:
-increase in volume
-decrease in bass
-decrease in treble

Use you multimeter's continuity setting Check against the schematic, make sue the connections are correct on your dual gang.

Good luck.

[JPGraphX]

I have an increase of volume. No decrease of bass or treble. I dont have an audio probe.

[JPGraphX]

How an audio probe works?

[GibsonGM]

Courtesy of R.G.!    Please make this, and learn to use it, before you go further.  It will save you HOURS of guessing, trust me!!!!!!  Don't forget to put a capacitor in series with the probe.
I made mine out of an old meter probe, works great...so you can actually reach in and touch the thing you want to probe...

http://www.diystompboxes.com/pedals/debug.html

[JPGraphX]

Good Thanks, where should I start By probing. Can you give me some tips? Like before diode what should I hear, after it.. Etc..

[JPGraphX]

Am I looking for a cut of signal?

[JPGraphX]

I built the probe and it is working. I have a realll hard time understanding from where to start. No sound from bot side of my GE diode. But I cant figure the order with the schematics. Someone can help me please?

[JPGraphX]

May I damage anything on my amp or pedal By probing everywhere?

[midwayfair]

May I damage anything on my amp or pedal By probing everywhere?

No.

Pull up the schematic. This is going to be tough because we're not allowed to post this particular schematic here. But anyway, you want to follow the audio path. Look at the circuit and start from "in." Then gradually probe at the intersection of each part. Note how the signal changes. Work your way toward the gain pot. You need to find out if signal is making it to that part of the op amp, and if it's being amplified. You need to figure out where you're losing signal to pinpoint the parts that aren't working.

This is going to be tedious but doing it properly will teach you about the pedal in ways that talking about it on a forum won't. An audio probe is such an awesome tool for debugging. Honestly I can't fathom how I debugged anything without it besides resorting to guesswork. To me it's every bit as essential as a multimeter.

[JPGraphX]

Hey guys! I built a second Chimaera for my friend and I have the exact same problem! No gain (overdrive) only a boost of volume! So I think it is not a bad component..! That is very weird!

JP

[midwayfair]

Hey guys! I built a second Chimaera for my friend and I have the exact same problem! No gain (overdrive) only a boost of volume! So I think it is not a bad component..! That is very weird!

JP

Have you verified with your multimeter that the gain pot is correct according to the schematic? Did you follow my suggestions with audio probing in the last paragraph?

We can't give further suggestions until we know that you've pinpointed the issues. I've built a klone on the Chimera board. I doubt it's a PCB problem.

[JPGraphX]

Im going to probe very carefuly tomorrow. Am I suppose to get signal to both side of the 2 GE diodes?

[Mike Burgundy]

on one side of the Ge diodes - the other is connected to ground.

[JPGraphX]

Anode or cathode side should have ground?

[armdnrdy]

D1 the anode goes to ground, D2 the cathode (stripe) goes to ground.

[JPGraphX]

Okay there is an error on the pdf of my build. C7 and C8 are reverse. Do you think it could solve my problem? I'll try it tomorrow.