i think thats the power supply board for the rear projection screen in your cab,i think its a mitsubishi but you can check by looking at the back of your cab.
i know similar replacement boards for other models can be very expensive so a repair maybe the route to take
i am in the process of fixing an early mitsubishi 50p-ghs41 power supply that took a drink,they are not the easiest of boards to fix.
do you know the problem with your power board