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Discussion Starter · #1 ·
I have a silicon fuzz that can operate at 9 or 18 volts (says so right on the pedal). I was rearranging my board and it made more sense to run this pedal using a battery adapter to my power supply. In other words, rather than running power to the jack on the side of the pedal, I added a battery clip adapter to the power cable and connected it to the battery terminals inside the pedal. The pedal hummed alot made some weird noises but worked for a while. Then it got really 'gated' without any real attack on each note. It sounds like a broken Atari 2600 at times, but at other times it sounds right for a moment then goes crappy.

I am wondering if 18volts through the battery terminal (rather than the power input jack) damaged the pedal. I opened up the pedal to see if anything looked mess up. Check out 'D1" on the board (right by the footswitch). Is it fried?


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If that's a resistor then yes, it looks like it's toast. You can find from a schematic or reading the coloured bars (assuming the carbon wipes off) and you can test its value with a multimeter.

Edit, if the naming scheme holds, that might be a diode and not a resistor.
 

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D1 is a diode.
Likely a power protection diode as it's not part of the 'fuzz' circuit itself.
Looks a little rough.
Easily replaced for < $1.
Make sure the white stripe is facing the same way when you replace it.
There's a look inside & a schematic here.
 

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Yep, a diode. Doesn't look especially healthy, from the picture, particularly compared to the picture Ray linked to.

If the schematic linked to is correct, those 2N3904 transistors are pretty indestructable. In most instances, whatever protection is included in the circuit for external power, is also applied to the battery source.

Um, are you sure the orientation/polarity of the power you provided was correct?
 

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Solder joints at either end of that diode look pretty non-existent too...
Melted? Best test without a meter - hold the part under your nose & take a good whiff.
If it smells like a burned diode, well, you can guess the rest.
I'm with mhammer, the only way this should happen is if the power supply polarity was revered -
Pretty easy to do when you look at a battery clip & the small connector is the (-ve), i.e., the opposite of what we're used to thinking looking at a 9V battery!
A '1N4001' would be a decent replacement.
 

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Discussion Starter · #7 ·
Thanks for all the info everyone! Much appreciated.

The pedal's power requirements are not reverse polarity running off a normal possibility. Miss it possible that, while running to the battery clip polarity somehow became reversed? The pedal did work.

Thanks again,
TG
 

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It's not clear if the diode is 'in line' with +9v or if it bridges 9v and Ground. Probably bridged from the looks of the heat buildup.

As a quick test, you could just clip the top end (as pictured) of D1, then power it up with 9v power. I'd suggest trying the adapter plug first, just in case the battery connector is fubed (unlikely, but if D1 was hot enough to melt solder...). If the pedal powers up, try the battery.

Best to isolate the pedal, (guitar/pedal/amp) for the test. If you apply power and get no signal, unplug the power asap. It can't hurt to try and you will get a better picture of how to proceed with a repair.
 
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