egodriver help

[randel_07]

ok so basically i'm not getting any overdrive.

vol control works, tone control works. but even when the gain is all the way up, there is no overdrive
here's my pcb



there's that one cap that's sticking out, but i think it's not what's wrong

[maysink]

You sure you have the right cap values for C4 & C11? C11 looks to be in the power section of the circuit but C4 appears in the transistor/diode clipping section. At least I think that's clipping section...

[randel_07]

i have 1nF (102) for C4, and 100 nF (104) for C11

[madbean]

What kind of op-amp are you using? Did you use 2n7000's for the mosfets? Do you have a DMM so you can give us some voltages of the pins of the amp?

[maysink]

Yep, that's right! Do you have 4 pots in this build? Check all your solder joints and maybe try a different opamp. You can see the components in the drive section in the schematic--double check all them. Good luck!

[randel_07]

I'm using a TL082CN op amp, and the readings are

1,2,3,5,6,7 = ~4.57V
4 = 0.04mV
8 = 9.14V

i'm using 2n7000's too

thanks for all the help btw. truly appreciate it

[jkokura]

Based on those readings I'd put money on the pot being wired incorrectly. It looks to me like you're eiter running a dual volume or dual gain pot system with the 2nd 3PDT switch. Perhaps you should share exactly what's going on in your pedal and also give us the readings from the 2N7000s as well.

Jacob

[randel_07]

o yea. basically, the other pot and 3pdt switch is for a SHO circuit
because i wanted a boost before the ocd. the SHO works fine, i just dunno why the ocd doesn't

[madbean]

Yeah, voltages are good, although I do wonder where that stray 4nV comes from.

You aren't going to want to hear this, but I don't think there is much you can do without first dissembling the board from the enclosure and working on it individually. If it were me, I would hook the board up to my testing rig without any switching to see if it is indeed working properly. If so, then you know it's a wiring problem in the enclosure. If not, then it is an actual problem with the build, which means you would have to remove it anyway.

Sucks, I know, but the process of elimination is sometimes the best route to take when debugging.

[randel_07]

haha yea i figured i had no choice so i started doing that already
but i have no more time, so i'm just gonna have to finish debugging when this semester ends

thank you for all the help

[jkokura]

Sometimes a break from a pedal can be the cure. Let us know when you need more help.

Jacob