Power Mac 8100 was bought as non working. I plugged it in and after 4 seconds, something blew in the PSU. When I opened the PSU, I found out that fuse was blown and the PSU was very dusty. I cleaned it an then replaced the fuse and plugged it again, now there was another bang, but the fuse survived (it is the same rating as the original). Then I tried it again, but now I got some smoke coming out of the area pictured below. There are two a bit charred resistors that measure 84 ohms across both (wired in parallel), however the center marking is burned off, so I don't know what resistance were they should be.
I believe that something must be shorted down the circuit.

Suggestions?