Posted By
Imperious
on 2014-03-29
21:16:41
|  Re: Suspected PLUS/4 Ram fault
Sorry, hit the key for post by mistake (and cannot see a way to edit)
DIAG264 was giving 3 flashes for U13, so that was changed 1st which got rid of the D on the screen, the photo I'll post is after U13 was replaced. After replacing U11 and U15 DIAG264 moved onto the high ram test which gave me a BAD at $430A-08 MUX-UP. The 08 is $08 which is decimal 8 which corresponds to U14.
After changing that all RAM, ROM tests passed with flying colours.
I plugged in joystick, sd2iec, and audio and ran a game and demo, all working very nicely.
Here is links to the pics I took.
http://tinypic.com/r/23saes4/8
http://i57.tinypic.com/29llriu.jpg
http://i60.tinypic.com/16h8114.jpg
http://i61.tinypic.com/59uejn.jpg
http://i62.tinypic.com/21ozrlk.jpg
A BIG thanks to Crock for DIAG264, no doubt I would have replaced all the ram chips without that and the documentation that I have read. Once I got my head around how the data bit system worked it all became a lot clearer. Another Plus/4 working nicely.
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