Posted By
Gorack
on 2015-04-04
20:48:34
|  Re: Faulty Plus 4
I had this exact problem. When first turned on the plus 4 would work normally but after a few minutes it would do what paulcan2 describes. I guessed that it was failing when the machine heats up. I wrapped an ice cube up and placed it on each chip until I found that the 6551 UART was the culprit. While the ice cube was on the chip the machine would work perfectly. It was weird, touching the chip you could not feel that it was getting hotter, but it must have been since the ice would stop the problem and the machine work. The solution:- Since i don't really need the UART for 99% of the software I simply cut the 5v trace on the underside of the circuit board to disable the chip.
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