Test with 15V Alim . Resistor has burnt . Why ??

[manu698]

Hi.

I have a SDD300 clone pedal I have build (Dirk Hendrick schematic)
The pedal runs perfectly with a pedal alim (9V/120mA isolated output on pedal alim, so as with individuall 9V/500mA )

I have found a 15V/1000mA in my stuff and I decided to gave it a try , even if I was not sure it would work.

I have tested, and it doesn't work   . The resistor directly at the input of DC feed has burnt immediately. Totally burnt (black color)
it is a 22 ohm / 1/4W.
I suppose it didn't like all the 1000 mA (??) and has overheated, but I would like to better understand.
Or it is maybe a polarity problem (with a resistor ??)

Why exactly has this resistor burnt?
What does this resistor makes exactly at this place ?

Many thanks in advance.

[Fender3D]

What does this resistor makes exactly at this place ?

Maybe it's waiting for schematic link? 

[R.G.]

As a very raw guess, the polarity of your 15V supply is backwards, and the protection diode in ypur pedal is placing most of that 15V across the resistor.

But there is no way to give you anything except a very crude guess unless you post a schematic.

[manu698]

Sorry.

Here is a link to the veroboard layout and schematic
R7  22 Ohm has burnt.

https://www.dropbox.com/s/f30972didzm2qq9/SDD3000%20clone.JPG?dl=0
https://www.dropbox.com/s/wlfqc0zvslqcs42/SDD3000_preamp.pdf?dl=0

[manu698]

I didn't think at first about the polarity inversion, but I really think it could be the cause.

What else could have been damaged then ? I d'ont see anything special. All other Resistor value are correct .
Diode D5 ?
Condensator C9  / C5 ?

I like this pedal and will order parts for fixing it for sure.

[merlinb]

I didn't think at first about the polarity inversion, but I really think it could be the cause.

What else could have been damaged then ?

Probably nothing else is damaged. The resistor acted as a fuse, which is a good thing!

[manu698]

Thanks !
I would be happy it it could be only this resistor.

Just in case, pictures of the pedal befor the burning  !
https://www.dropbox.com/s/ggticpsli7gkf7m/SDDclone%201.bmp?dl=0
https://www.dropbox.com/s/8frf7yec7mi1xoo/SDDclone%202.bmp?dl=0