ThunderPuss problem (updated with a new noise-problem)

[Loztboy]

I'm building a ThunderPuss, and I'm using a Alpha angled pc mount 5k rev log pot. (mounted on top of the components)
When the pot is at minimum the volume is FULL-on, when I rotate it clockwise the volume turns to uniti gain after about 8'O clock and stays that way all the way.

What have i done wrong

[Haberdasher]

Hi

I think you may have pin 3 mounted where pin 1 goes and pin 1 where 3 needs to be.

Also, I would probably mount that pot on the solder side.  You'll need to put something on the back of the pot so it doesn't short to your solder points.

anyway, that's my guess

cheers

[mgwhit]

You must have mounted the pot backwards.  My Thunderpuss gives close to unity gain at minimum dial setting (and goes up from there as you would expect).  I think this is because the volume pot does not act like a voltage splitter  at the circuit output point the way most Output/Volume pots do, but instead acts like a variable resistor manipulating the bias/gain of the MOSFET.  As soon as I get a chance, I'll check my Slambox/SHO and see if it behaves similarly.

[madbean]

It should be mounted underneath.

[Loztboy]

I followed the instructions in the pdf and thought the wiringdiagram showed the component side of the pcb.  I will try to swap leg 1 and 3 tomorrow and report back. Thanks

[mgwhit]

Just to follow-up on my previous post, the SHO puts out slightly less than unity gain at the minimum knob setting, too.  Just the nature of those circuits.

[madbean]

I followed the instructions in the pdf and thought the wieringdiagram showed the component side of the pcb.  I will try to swap leg 1 and 3 tomorrow and report back. Thanks

Correct, it does show the component side. The wiring diagram is kinda fail on my part. It's labeled as 1-2-3 but the illustration of the pot does not match it correctly. I can fix this. But, it is also pretty clear from the build pic that it's supposed to be wired that way.

[Loztboy]

I mounted the pot underneath, and it now works like it should.
Thanks all!

I'm going to test it with my 59' Bassman RI at rehearsal now

[madbean]

Woot! Glad it was an easy fix.

[Loztboy]

hmm, I got a new problem now.
Some times when i plug inn dc power, I get a strange noise.
If I unplug the dc jack and plug it inn again the noise is gone.
When it's working I can play for hours without having any problems.
What can be wrong ?

Here is a crappy video:

[gtr2]

Do you possibly have something shorting to the enclosure?  Does it do the same thing if you tap the enclosure?

Josh

[Loztboy]

I have checked for shorts, tapped the enclosure and pulled and pushed all components without being able to reproduce the noise when it is in "working-mode"

The same thing happens when i leave the dc-plug in the pedal and remove/insert the poweradaptor into the wall.  
When the noise appear and I remove the power, the noise fades slowly together with the led light.

Here are some pictures of the componentside.
I have taped off the pot so there is no short between the pot and pcb.

The Led legs are not cut yet. I have some long legs on the caps to be able to bend them to make space in the enclosure.

And again, when i plug in the dc-plug i either get noise or not. the noise does not appear when it is in "working-mode"

[gtr2]

It may just be a faulty power jack or a cold joint on the jack.

Josh

[Loztboy]

I have tested with a new dc-jack with the same result.
Could it be a bad Cap?

[bigmufffuzzwizz]

I have tested with a new dc-jack with the same result.
Could it be a bad Cap?

Try tracing with an audio probe until you find the culprit.