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Projects => Tech Help - Projects Page => Topic started by: Loztboy on August 03, 2011, 09:57:47 PM

Title: ThunderPuss problem (updated with a new noise-problem)
Post by: Loztboy on August 03, 2011, 09:57:47 PM
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 :)
Title: Re: ThunderPuss problem
Post by: Haberdasher on August 03, 2011, 10:15:12 PM
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
Title: Re: ThunderPuss problem
Post by: mgwhit on August 03, 2011, 10:18:19 PM
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.
Title: Re: ThunderPuss problem
Post by: madbean on August 03, 2011, 10:19:51 PM
It should be mounted underneath.
Title: Re: ThunderPuss problem
Post by: Loztboy on August 03, 2011, 10:30:50 PM
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
Title: Re: ThunderPuss problem
Post by: mgwhit on August 03, 2011, 10:38:37 PM
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.
Title: Re: ThunderPuss problem
Post by: madbean on August 04, 2011, 12:49:46 AM
Quote from: Loztboy on August 03, 2011, 10:30:50 PM
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.
Title: Re: ThunderPuss problem
Post by: Loztboy on August 04, 2011, 03:25:52 PM
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 :D
Title: Re: ThunderPuss problem
Post by: madbean on August 04, 2011, 04:22:13 PM
Woot! Glad it was an easy fix.
Title: Re: ThunderPuss problem
Post by: Loztboy on August 04, 2011, 09:18:25 PM
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:
Title: Re: ThunderPuss problem
Post by: gtr2 on August 04, 2011, 09:24:11 PM
Do you possibly have something shorting to the enclosure?  Does it do the same thing if you tap the enclosure?

Josh
Title: Re: ThunderPuss problem
Post by: Loztboy on August 04, 2011, 09:48:58 PM
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"
(http://home.online.no/~tv79/gitarnorge/TP/tp1.jpg)(http://home.online.no/~tv79/gitarnorge/TP/tp2.jpg) (http://home.online.no/~tv79/gitarnorge/TP/tp3.jpg) (http://home.online.no/~tv79/gitarnorge/TP/tp4.jpg)
Title: Re: ThunderPuss problem (updated with a new noise-problem)
Post by: gtr2 on August 06, 2011, 01:30:17 AM
It may just be a faulty power jack or a cold joint on the jack.

Josh
Title: Re: ThunderPuss problem (updated with a new noise-problem)
Post by: Loztboy on August 08, 2011, 01:43:01 PM
I have tested with a new dc-jack with the same result.
Could it be a bad Cap?
Title: Re: ThunderPuss problem (updated with a new noise-problem)
Post by: bigmufffuzzwizz on August 08, 2011, 07:10:11 PM
Quote from: Loztboy on August 08, 2011, 01:43:01 PM
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.
Title: Re: ThunderPuss problem (updated with a new noise-problem)
Post by: Loztboy on August 09, 2011, 08:27:15 PM
I think I finally figured out what was wrong.
There was a bad trace between c3- and the pot leg.
This probably happened because i mounted the pot backwards and had to desolder it to put it on the right way.
Thanks for all the help.
Title: Re: ThunderPuss problem (updated with a new noise-problem)
Post by: Loztboy on December 10, 2011, 12:39:46 PM
Update I found out that the noise problem was caused by a bad power supply.