My hm-2 failed, please help me fix it

[gorgieboy]

Pedal:Boss Heavy Metal HM-2

Schematic: http://www.hobby-hour.com/electronics/s/hm2-heavy-metal.php

Fail description:Direct power from my brick stopped working so i put in a battery. Worked fine until i forgot to unplug the guitar overnight and drained the battery. Changed battery and nothing worked, not battery or direct power. Took it a part to take a look, saw nothing and put it together forgetting to put in the plastic isolation shield like an idiot. Stomped it and got power and weirdness. Realized my mistake and put it correctly together and now it works but only like 75%. It's lost it's beautiful buzzsaw edge and now it only works with direct power not battery?

I've gone through the PCB pretty thoroughly both on the component side as well as the soldering side and nothing stands out. Gone through wires and connections as well as measuring the conductivity of the board and found no irregularities.
I tried to do some more advanced measuring and look at the schematic but it's all chinese to me, guess i'm not there yet... 

As you guys can probably see i'm kinda new to this so if anyone could help it would be much appreciated. Also let me know if there is any necessary information missing....

Thanx

[Fender3D]

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

[JerS]

I have experienced these exact symptoms with an HM-2 for a client before. In my client's case, it turned out that the power protection diode had partially failed drawing some power to ground. With a power supply there was enough "juice" to allow the pedal to work - albeit not at full strength. It sounded like it was running with a near dead battery.

Try measuring the voltage after the protection diode - if it is not near 9v, then you may have the same issue. If so, clip out the protection diode and test again. If it works - replace the diode.

Good luck!