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Retrocomputer, Heimcomputer und Videospiele der 80er

IBM PS/2 model 55 repair 

IBM PS/2 model 55 repair  A very common sight on IBM PS/2's

The errorcodes basically mean the CMOS is corrupted. Most of the time this is caused by an empty battery...

IBM PS/2 model 55 repair  The IBM PS/2 model 55 uses a Dallas DS1287 Chip, which has an integrated battery...
IBM PS/2 model 55 repair  As i do not have a replacement Dallas chip i opted for the "hacking the Dallas method".

First i had to remove the cablebinder.

IBM PS/2 model 55 repair  Then i carefully removed the Dallas DS1287 from its socket.
IBM PS/2 model 55 repair  Dallas removed...
IBM PS/2 model 55 repair  I marked the 2 positions...
IBM PS/2 model 55 repair  and started to file using my smalest file.
IBM PS/2 model 55 repair  Here you can see the internal bend up pin and on its upper end the place where it is soldered to the internal battery.
IBM PS/2 model 55 repair  I filed until the connection between the pin and the battery was broken to disconnect the internal battery.
IBM PS/2 model 55 repair  I used a CR2032 cell as a replacement.
IBM PS/2 model 55 repair  Two wires soldered onto the two upturned pins.
IBM PS/2 model 55 repair  And connected to the cell. At the time i had no cell-holder. With a cellholder it would look much more professional ;-)

As you see the positiv end of the battery goes to the right side of the dallas-chip.

IBM PS/2 model 55 repair  I fixed everything with tape and ...
IBM PS/2 model 55 repair  Using the right "Reference Diskette" the PS/2 booted fine!

With the "Reference Diskette" you have to set Date and Time ...

Autor: Thomas Gutmeier