Taito The New Zealand Story arcade pcb repair

Game didn’t boot and immediately shut down the power supply.  Indeed, a meter confirmed only 2 or 3 ohms of resistance between GND and +5V at the edge connector, so something was shorted on the board.  There’s really no easy way to find a short on a board like this.  Removing all the socketed chips to eliminate them is a good first step as well as looking for physical damage, especially to capacitors that may bridge GND and +5V.

Luckily I found the fault fairly quickly – when I lifted one of the legs of the ZD1 component the short was gone and the board played correctly.  I believe the design of the board is ZD1 provides some overvoltage protection by bleeding the +5V line to GND if required, however in this case it had simply failed and shorted +5V to GND.