Star Tech Journal

Sega Audio Problenis: System 16B
Custoni Chip Substitution
Reinhard Bangerter
NOi
Laguna Hills, California
SUBJECT
SYMPTOM
A large number of Sega kit games (ie. Shinobiand
Altered Beast) have been experiencing audio
problems.
Shinobi:
EPR-11377 EPR-11361
EPR-11372 EPR-11287
Most of the boards sold in America have custom
CPU chips for security. These chips have an
altered instruction set so the Z-80 code in Rom
is encripted and will only run with the proper
decoding.
•
This chip is very sensitive to voltage spikes and
may even have battery backup to hold the
encription table. This is the chip that is usually
the culprit if your board is not making any game
sound or only a few sounds.
SOLUTION
After the fear of bootlegging is over (conjecture
on my part), Sega of Japan provides Rom code
that will work with ordinary Z-80 B's. The new
software should be available from your distribu-
tor. Or if you have had one repaired already, you
have the new software.
There are two types of top boards for System
16B, therefore there are two different Roms to
update your PCB to use a standard Z-80 B. I do
not know if the second type of board was used in
Altered Beast, so I only have the one substitute
in the table that follows.
0
0
0
TYPE
7A
27256
27256
l0A
27256
l0A
Altered Beast:
EPR-?????
CAUSE
Pea LOC
NEW#
Sound problems on Sega System 16B games.
EPR-11671
NOTE
After replacing the Eprom you must replace t h ~
Custom 40 pin CPU on the bottom PCB with a Z-
80B (not Z-80A).
AMP SUPPLIER
The MB3733 audio amp is available from MCM
Electronics for $5.36 in single quantities. 800/
543-4330. Ask for a catalog. They are an excel-
lent source for original Japanese parts (Linear
IC's and 2SXXXX transistors).
0
0
0
Statistical Item ...
Video entertainment is a 10 billion
dollar a year industry. 70% of this
total is Coin Op. The remainder is
from home systems... from a re-
cent article in Business Week.