FYI, capacitor C141 is directly across the power input. If you apply reverse polarity, you will almost certainly blow that capacitor. Either check it for a short, or remove it to see if it solves the problem. Of course, replace it when done.
Ummm, you did make sure to turn the LOCK switch "on", right?
Anyway, here's the power path:
1. From the power jack on the AVPower board, negative connects through a small jumper to the black wire, which goes to P103, pin 1, then to board ground.
2. From the power jack on the AVPower board, positive connects to the red wire, which connects to P103, pin 2.
3. From P103, pin 2, it goes to C141 (47uf, 25v) and also through L101 to P102, pin 2
4. From P102, pin 2, it goes to the Power Switch.
5. Back from the Power Switch, it goes to P102, pin 1.
6. From P102, pin 1 it goes through L102 to P404, pin 2.
7. From P404, pin 2, it goes to the Lock Switch.
8. Back from the Lock Switch, it goes to P404, pin 1.
9. From P404, pin 1, to goes to D101 anode (that's the "30D2"), which is the polarity protection diode.
10. Out D101 cathode it goes to C101, C102 and C103 (330uf, 25V) in parallel, then continues on to R101, R102, R103, and R104, which are actually jumpers. These jumpers feed the separate parts of the actual power supply circuit. This was done so each circuit could be powered individually during board design.
You should be able to trace the power to that point. Make sure to check the voltage against both grounds, the one on the AVPower jack, and the common ground on the board.
Charlie
PS. I suppose, if there was a place to upload it, like say a sticky entitled "Repair Guide - Interface Unit", someone might be pursuaded to supply an abbreviated schematic of the above circuit......(I'm just saying..!)
Edit: Added reference to R103, R104.
