Power supply repair question....

[Seven64]

So I have a Boss DD20 that just took a crap on me. 

The power light comes on, but nothing else works.  I am thinking there is a problem in the power supply, as the rest of the board is not getting voltage (apparently)

I found the factory service manual:

http://www.scribd.com/doc/77543643/Boss-DD-20-Service-Notes

I have read on the internet where a similar problem happened that it was the protection resistor.  The BOM calls R76 a Poly Switch, part number MINISMDC075.  I can find it on mouser/digi, and they seem to be cheap. 

Is anyone familiar with what exactly this is?  I can see it is polarized, but according to my multi meter it has continuity both ways.  Does this mean it is not working properly?

I just plugged it in again to try and see if anything was warm when BAM, I burned my finger on IC12.  This appears to be a step down voltage regulator.  I could not tell if q17, a power mosfet was also warm.

I figure a bad protection resistor would cause the step down voltage regulators to go crazy, is this what is happening

[DiscoVlad]

A Polyswitch is a current controlled resistor that is used as a resettable fuse for circuit protection against excessive (fault) current.
At their normal working current they have a low resistance, but if there is a short in the device they're protecting, the increased current through it causes it to heat up and become a very large resistance (10s of megaohms). Once the power supply is removed they cool down, and go back to a low resistance state again.

So basically it's like a fuse - the fact that the fuse has tripped doesn't necessarily mean the problem is with the fuse, but is more likely somewhere else in the circuit.

Next up is IC12 - the DC-DC converter and transistor, this could be getting hot because one of them is faulty, or more likely, something it's connected to has shorted out and is overloading them. Looks like those parts are responsible for the 24 and 11V supplies - check that these voltages are good.

Are there any obviously burnt components on either of the boards?

[Seven64]

no, everything looks fine

[Seven64]

getting 3.3v  off of c98, 23v off of q15, 11.5v off of c100

i really dont think that ic12 should be hot tho, should it?