A lot of Williams games run their CP's through an interface board before going to the CPU. Follow the wiring harness from the CP to the board and check the connectors to that board for cold solder joints, etc.... Sometimes that little board goes bad and causes CP problems. But... try two things first. Jumper the ground from down to the ground on the up to see if it works. If it does, then you have a bad ground and can just run a new jumper to the ground lug of your up. If it still doesn't work, remove your down wire and move your up wire to the down switch and see if pulling down on the joystick makes the ship go up. If it does, then the switch or wiring is probably bad, regardless of your jumpering. Don't forget to move them back afterwards. It's probably a good idea to check continuity from the pad on the board to the switch just in case there is an internal break in the wires or connectors keeping the signal from being routed properly.
By the way, a lot of times RAM errors are caused by unstable power supplies rather than actual bad RAM chips. If you're getting the same RAM error every time, then swap the bad RAM chip with one from a different location to see if the error changes. If so, replace the chip. If not, obviously check the chip socket, but then go to your power supply. If you're getting different RAM errors, then go directly to the power supply.
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Topic: Defender Control Problem (Read 1886 times)
