Weird Doombutter problem

[Guybrush]

Hey there

I've just finished off building a Doombutter that has been on the shelf for ages and surprise surprise it doesn't work.

I doesn't work in a very specific way though. I hooked it up to my test rig and when I turn it on the LED flashes on and off and the circuit makes a clicking sound in time with the flashing.

I have no idea what the problem is so was hoping that someone might have an idea. I've checked the soldering and while far from perfect I can't see any solder bridges or major screw ups.

Any help would be greatly appreciated. Thanks in advance. Pictures below.

[hammerheadmusicman]

A couple of the joints look like they might be dry, and some bridging to the ground plane.

i would say, trim off all the excess from the pads, then reflow all the joints. That generally sorts out 90% of my problems!

[midwayfair]

Good to see you back, Guybrush.

Have you tried audio probing? The audio path in this pedal is pretty simple, so you should be able to follow it to find the place you lose signal. The good news is your LFO's working -- that's the harder part to debug.

[Guybrush]

Cheers man. Life's been getting in the way of late so had to put pedal building on the back burner.

Thanks for the help guys.

I'm not sure if the LFO is actually working. When I said the LED flashes, I was referring of the on/off  indicator. Not the LED on the board.

I've got an audio probe on my test rig but it's been that long since I used it I've forgotten how (that's what she said). I'll figure it out and do some testing with it.

Hammerhead: I'll get re-soldering and hopefully it'll do the trick.

Thanks again.

[Guybrush]

I've re-flowed the joints but it's still the same I'm afraid.

I did notice however that the legs of the socket that the LM78L05 is sat in get incredibly hot when the circuit is powered up. Is that normal?

I can't find my notes on how to use the audio probe. Could anyone point me in the right direction of something that I could read? I've Googled but all I can find is how to build a prove. Not how to use it.

Cheers guys.

[hammerheadmusicman]

try taking voltages, that'd give a better idea, if the regulator is getting hot.

[Guybrush]

Just tried it again on my test rig to take the voltages of the regulator and it (the regulator) instantly started smoking. So I'm guessing there's definitely something wrong with it! Ha.

Here's the one I'm using http://pages.ebay.com/link/?nav=item.view&id=190816232397 do they look right?

[hammerheadmusicman]

That happened to me with an etched cave dweller.. replace it and see what happens. turns out i had a solder bridge somewhere near the regulator. Be warned though, when they smoke, they are F'in hot! I had my brain switch off and just grabbed it, not fun!

[the3secondrule]

Good to see you back, Guybrush.

Have you tried audio probing? The audio path in this pedal is pretty simple, so you should be able to follow it to find the place you lose signal. The good news is your LFO's working -- that's the harder part to debug.

There's no LFO on the clarinot, it the led/ldr combo are driven by the envelope from the 386

[the3secondrule]

Just tried it again on my test rig to take the voltages of the regulator and it (the regulator) instantly started smoking. So I'm guessing there's definitely something wrong with it! Ha.

Here's the one I'm using http://pages.ebay.com/link/?nav=item.view&id=190816232397 do they look right?

Double, triplecheck the pinout on your 5v reg - they can vary by manufacturer. this is something i've learned the hard may more than once   

[Guybrush]

Ahh! So this might explain why in some build reports the regulator is the 'wrong' way round?

Like in Bigrigg's build here: