6532 expansion card not working

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6532 expansion card not working

Postby Norbert » Feb Mon 27, 2012 12:28 am

When trying to play 'Farmer Brown' I noticed that the second 6532 (in the expansion slot) does not seem to work properly. The game gets a random pattern from location $1704 in the working area of the second 6532. The whole data area between $1700 and $173F only shows zeroes. It makes no difference to change the places of both 6532. I know that at least the 74138 and one of the 7400 are responsible for addressing the expansion area, but replacing them as well as the 7404 (on the expansion board) with new chips has no effect. Apart from that my Micro-Kim behaves normal.

Has anybody got a hint for me how to proof and fix this?

Thanks in advance
Norbert
Norbert
 
Posts: 17
Joined: Feb Tue 15, 2011 2:17 am

Re: 6532 expansion card not working

Postby Norbert » Feb Mon 27, 2012 11:24 am

I found the problem: tricky, there was a little part of solder that 'bridged' PB7 and IO3 ( Pins 19 and 22) under the plastics of the expansion connector.
Norbert
 
Posts: 17
Joined: Feb Tue 15, 2011 2:17 am


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