Posted By
MMS
on 2019-02-10
15:04:29
 |  Re: Dead Plus 4 (not by TED or CPU)
Hi,
The experts will surely help. My 2cents:
Our usual "toplist"
8501 checked
TED checked
PLA I do not see on your list.
RAM checked
PLA in C64 is a similar troublemaker, than in 264 series. So I think it worth a try. C64 version is not the same.
There are some modern retrofit versions too.
Commodore 16, 116 and Plus/4 replacement for PLA Programmable Logic Array - 251641-02
The problem:
A faulty PLA can cause: Blank screen, no border, colored screen or flashing color garbage instead of startup screen, intermittant loss of cursor, screen freeze and/or program crashes after warmup or random characters on screen.
The original chip 251641-02 runs very hot and is very poor reliable. This is the first cause of problems on Commodore computers.
Replacing the fault PLA with an original chip doesn't fix the problem definitely due to their poor reliability.
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