Boss MT-2 Metal Zone question

[Danglin' Fury]

So I have this metal zone on the bench. No lights come on or anything. I cracked it open and saw the diode by the A/C adapter input was charred... Badly...I replaced said diode and cleaned up the board as best I could. Yaaaaay! I get a clean tone out of it, but when I hit the switch, the red light comes on but I get an extremely quiet distortion tone. It is barely audible. Could it be the IC that is in the distortion circuit? Has anyone seen this before? Thanks for looking.

[Helmholtz]

If it's the typical "protection" diode being reverse wired across the power supply input, it will only protect the rest of the circuit if fails shorted in case of wrong polarity.
Otherwise opamps and ecaps might get destroyed.
I hate this "protection" circuit.

Try to find and post a schematic.

[g1]

schematic attached

[Danglin' Fury]

Thanks for the schemmy, G1

[Mick Bailey]

Check you have +9v on the board as well as the +4.5v. A check of the opamps is if the outputs are skewed heavily towards 9v or 0v - they should sit at roughly 4.5v.