Box of rock issues, need help

[thomasolsen84]

Hi. I've got some issues with my recent build. Iys the box of rock on tagboard. I been trying to find the ussue and rebuilt it once. I've built one of these before without issues but cant get this one to work. Ive got bypass signal and a weak signal when on. No overdrive and the gain knob has to be turned all the way up to get any sounds at all.
The voltages i got is beginning from the left transistor.
Q1 S: 0.98 G: 2.47 D: 6.86
Q2 S: 1.66 G: 2.38 D: 6.85
Q3 S: 2.07 G: 2.34 D: 6.86
Im a newbie on this stuff and dont really understand all the physics on this stuff.
9v from power supply going through a 82r resistor measuring only 6.88v is this right?
Any help greatly appreciated.

[GibsonGM]

Hi Thomas, welcome!

Re-check every single connection (especially the pots!), and make sure your ground connections are all good.  Be sure you got the pinout for the Q's correct!  Sometimes they are put in backwards, esp. when some (like these) can have other pinouts.   Check that the diode at Q1 is pointing in the right direction.

If still not working, make an audio probe and try to listen at the gate of each Q..that will tell you if the stage before it working correctly.  Be sure to clip the alligator clip ground to your circuit ground!   At some point I think it will go  "ok...next one's ok....oh, this one is VERY quiet!" and you will have an idea where the error lies, and can at least tell us where the signal dies.  Most always the problem is builder-error, it happens to everyone.  Just be patient...

Run off a battery for testing.

Audio probe: https://www.diystompboxes.com/pedals/debug.html

[thomasolsen84]

Thanks a lot for your help. I made an audio probe. Reflowed every solder points. Im getting the same results as before. Probed from the jack input to the switch and to the input on the board.  Getting clean signal, no overdrive. Probed every point on the board getting only clean signal. Except on the ground points im gettig no audio. Im lost on what is wrong. I know the circuit is verified and I have built pne of these earlier.

[thomasolsen84]

I've checked the pinouts on the mosfets as well they are right. I have a cheap transistor tester not sure what to check for other than pinouts and type and polarity. These mosfets might be fake ones as they're chinese ones. I guess they're allright it must be something i did when building this.

[dschwartz]

Do you have spare mosfets? They are prone to die from static

[Keppy]

Your drain voltages are low, your power supply voltage is low, and your 5.1k resistors connecting the power supply to the drains look like they're actually 5.1R. I say double-check those resistors, and make sure your power supply puts out a full 9v when not connected to this circuit. Good luck!

[thomasolsen84]

Thats it. Ive managed to use 5.1 ohm instead of 5.1k. I stocked up on resistors and misplaced those in my resistor drawer :icon_rolleyes:awer. Thanks a lot i now got it going. I rebuilt it twoce and used loads of hours trying to find the problem. Again thanks a lot.