Because someone had added some jumpers like pinrepair suggest but made a mistake in them, they had created a short on this board.. search for the vaporized trace.
It starts at most right pin of the 2nd connector on the left, and goes along the bottom of the board (3rd trace from the bottom) and continues underneath the black capacitor. Most of it was just gone, only a shadow of where once some copper had been was left..
Bridge rectifiers also had been replaced and soldering wasn't done very professionally. Too much heat (and the game didn't work because some small traces that go to the legs of the bridges didn't have continuity anymore because they were just burnt). Some traces and the board was just burnt, thick blobs of solder where hanging around, ..
Seems they didn't have enough bridges with pins so they used the type with fast-on connectors. Bridges with fast-on connectors are easy to find here in Europe - the type with wires like used on WPC driverboards is not available in most electronic stores. So I can understand the reason why some repair persons use this type or bridge, it's not the first time I encounter it.
To connect this to the board they didn't use wires (like I've seen in the past). The legs of the old bridge rectifier had been cut off pretty high, so that the metal pins were sticking up. Fast-on connectors had been soldered onto these legs. The bridge then just snaps into place. Makes it a lot easier to replace in the future, no soldering is required anymore ! :-)
The back of the board didn't really like the heavy soldering of these fast-on connectors.
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