TECH Star Wars PCB

I have a Star Wars upright boardset that I am having some
issues with. I am getting Matrix Errors:

AFFFF
B0000
CFFFF
DFFFF
NNNF FNNN FFFF
NNNF NFFF FFFF
NNNF NFFN FFFF
NNNF NFNF FFFF

There are no ships or stars. The Screen also is about 1/3
smaller than the actual monitor...

I have a good / working boardset that I switched out the
PROMs with and that had no effect so I know it's not the
Mathbox PROMS.

Looking in the manual I see that the Serial Subtractor (8b)
is involved heavily with tests A,B,C,D so I am going to try
to change it out. The manual also says that missing ships
are most likely due to a bad Math Ready line but I don't get
that error.

So I am going to change out the IC at location 8b (Serial
Subtractor). The Schematcs say this IC is a "LS385".
Searching the internet essentially claims there is no such
part as a "LS385". Looking at the actual boardset the IC at
location 8b is labeled "AM25LS15PC"... Is this a typo on
the schematics? I find it hard to believe that you could
get the two numbers confused. When searching for AM25LS15PC
I did find some hits but none of them crossed with LS385...

Jono
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Received on Sun Aug 26 10:58:19 2007