Egad! My project is smoking...

[MikeH]

This design worked perfectly on my bread board but when I soldered it all together and plugged it in, there was definitely a burning smell.  Curiosity getting the best of me, I left it plugged in to determine the source, until I noticed smoke and burning embers comming from the volume pot.  Any idea what could have caused this?  It's a modified Tube Reamer. 

Here's the schematic:
http://www.runoffgroove.com/tubereamer.html

And I started with Torchy's vero layout: (It's in the torchy album page 13, under "reamer".  I didn't want to post it here without permission)
http://www.guitartone.net/vero.htm

And here's the layout for my build:

(C6 is 220 nf)

Basically it's the same, but I added a second gain type option, and a resisitor to adjust the output for LED use and a low-pass filter at the end.

[R.G.]

Take your DMM and see where you have the +9V supply connected to the volume pot.

[coffyrock]

just go with it... rename it the "tube smoker"..

[Alex C]

Take your DMM and see where you have the +9V supply connected to the volume pot.

I would check for a solder bridge between the bottom two tracks on the right side (VOL3 and 9V+).

[jonathan perez]

THATS HOT

[MikeH]

I don't see any solder tracks, and unfortunately my DMM took a trip off the kitchen table, so it's not really being cooperative.  I thought the same thing so I removed the pot and ran the power supply through it but nothing happened.

[David]

Smokin, smokin', volume pot just keep on tokin';
Smokin', smokin', it's burning up and I'm not jokin'.

Apologies to Boston...
I'll get me coat. 

[Psych0F0x]

hihi smoking pot.

Still pretty weird, pot that smokes itself.

I was messing around with one of my pedals when it wasn't in a case and suddenly there was a spark and some smoke. The pedal still works but the thing smells..

[MikeH]

Unfortunately mine doesn't work at all.  Can anyone find any flaws in my layout?  I checked my build and it matches up with the layout.

[R.G.]

Back to basics. Can you give us a set of voltages as in "Debugging: what to do when it doesn't work", including the voltages on the pots.

That should tell the tale.

[MikeH]

Yeah, I need to check the voltages everywhere, unfortunately I need to get a new dmm first, I sort of destroyed mine.   

[puretube]

between pin 4&5 there`s direct connection...
normal? - dunno the schemo -

but: "smoking is hazardous to your chips"

[MikeH]

That's a good question, the schematic is different from the Torchy layout, which is what I used to do the layout.  Basically it's just connecting pin 5 to the ground, pins 6 and 7 are wired together- however, on my bread board they would have been separated... I didn't think of that.  Eh boy...

[MikeH]

Ok, I figured it out.... who new sending a full 9v into the center lug of your volume pot would make it smoke and burn up?  Funny thing is, the pot still works!  Crazy...

[Peter Snowberg]

Glad you got it figured out.

When you send 9V into the wiper of a pot with one side grounded and you set to pot to a low value, it's like placing a little heater across the battery. The pot will still work over most of the rotation, but there will be a little area where the resistor element is charred. That spot will wear over time and will probably make for a scratchy pot.

[R.G.]

Ok, I figured it out.... who new sending a full 9v into the center lug of your volume pot would make it smoke and burn up?  Funny thing is, the pot still works!  Crazy...

...tee-hee... I did.

Take your DMM and see where you have the +9V supply connected to the volume pot.

How did I know? Ummm, there is a pile of leftovers from my educational process that have smoke marks on them. 

[Harry]

Hey that would make a nice... um effect. Build a box with a bunch of trivial components not related to the actual circuit and rig it so it starts overheating them to create lots of smoke and bad smells! 

[coffyrock]

instead of smashing guitars, just wire up a fake pedal that catches fire when stomped, then rage on it when playing a show!