Need help: HP9854B screen shows only an chess board.

Hi,

I could get an defect HP9854B for my little private collection.
The system looks very proper and I'm full of hope to get it back to
running state.

But for that I need some help from HP Expert which knows this system
hopefully as an senior HP technician.

I have nothing about this system, no manuals; no service books an no
knowledge about this system. So everything would be miraculous to get.

The system shows an enigmatic screen if powered up. I made a picture
which could be seen here (http://www.nadhh.hanse.de/10subm_Computer/
05subm_Hewlett-Packard/10subm_HP9854B/Images/defectscreendump.jpg).
The screen (the active area) is filled up with small black and white
blocks. Periodically the screen collapses or changes and it seem there
is something like the system's prompt line is shown for some
milliseconds.

Would be kindly to give some indications to me where I can look for
that error. Schematics and other diagrams I could already get from
here (http://www.hpmuseum.net/collection_document.php).


Regards
Juergen

 

The link was corrupted.
http://www.nadhh.hanse.de/10subm_Co...rd/10subm_HP9854B/Images/defectscreendump.jpg

 

Hi Juergen,

This pattern looks like a RAM problem.
Locate the RAM chips, unplug them (if possible), clean the pins,
then re-insert them again.
HP equipment often have a selftest mode, check out for a dip switch.
Maybe it is only a bad power supply, so you should check out that too.

HTH
Wolfgang