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Re: BBC Model B Very Ill
Posted by Ian Wolstenholme on Monday, November 18, 2002 at 22:21:37
Rich wrote:

Go for the easy bits first.

Turn the power off. Take the lid off. Then check that all the power leads from the PSU are seated firmly on the mainboard. Next check all SOCKETED ICs are seated, Finally check the keyboard connector at BOTH ends is properly attatched. It wont hurt to remove it and reseat it to be sure.

Give that a go first.

Rich.

Thanks for your help - sadly I have tried all of the above without any luck. I have even tried switching on with various ICs removed one by one but no success. I thought the problem might be associated with the System 6522 VIA which drives the keyboard and sound chip amongst other things but I have replaced the 6522s with chips from a working Model B but the problem persists.

The two 6522 chips (IC3 and IC69) are very slightly different - one is an SY6522 and the other an R6522-31. These are in the opposite sockets on the ill BBC to the working one but even swapping them round does not seem to help.

Any more ideas?



Ian
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