Star Tech Journal

Issue: 1988-December - Vol 10 Issue 10

SNK P.O. W. Credit
Modifications
~
Atari Assault
Leaf Switches
Neal Zook
SNK Corporation of America
Sunnyvale, California
Doug Hutton
EBSGames
Poway, California
SNK Corporation of America's Technical
Service Department has received a number
of calls regarding Prisoners ofWarintermit-
tently not giving a credit when a coin is
inserted. The problem does not seem to be
caused by the same component in every case
and we have not been able to duplicate the
problem in-house. Several customers have
been able to eliminate the problem by per-
forming one of the following:
PROBLEM
1. Adjust the coin switch actuator wire, in
some cases the problem can be solved by
adjusting the wire up slightly.
2. Replace the coin switch, several operators
have successfully eliminated the problem
simply by replacing the microswitch.
3. Install a capacitor across the coin switch.
This will eliminate the problem in every case
and not harm the game. We have heard that
using any value between luf and l0uf
electrolytic (at least lOvdc) will eliminate the
problem. This component is polarized, so be
certain that the (-) lead is conn'!cted to the
common (ground) terminal of the mi-
croswitch.
If you have any questions regarding Prison-
ers of War or these modifications, please
,~contact SNK's Customer Service Depart-
ment Monday through Friday, between 8:00
am to 5:00 pm Pacific Time at 408/736-
8844.
Has anyone else been experiencing frequent
leaf switch failure with the fire buttons on
their Assaults? The piece of spring steel that
adds tension to the fire buttons just snaps in
half. Ours have been failing at about one per
week, and at eight dollars a switch it begins
to add up!
SOLUTION
I fmally replaced our leaf switches with
micro switches and although the buttons
now have a "harder" feel to them, the players
don't seem to mind and rve had no problems
in over three weeks.
Sega Replies
Dari Davidson
I
~~aJ~~~..:~rvlce
Last nwnth's article "Resourcefulness• by Ronnie Belitz of Larlc
Amusement. Bristol, TN drew a response from Segds Manager.
J
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~:·
Currently, I have two motors on my table missing ;,.
brush caps. I have taken these items out of inven- : ~✓- ":
tory and sent the brush caps to distributors be- 1
cause of your report that they were unobtainable. J
The old administration at Sega would never have
done this, but I have a policy: I will do whatever it
takes to get a game up -no matter what! If there is
a way I can help the customer, any way, I will do it
(even if it means disabling an entire motor!).
Please remember this when it comes time to shop
any Segagame and you need to order parts. Ronnie,
I will do my very best to keep you out of K Marts in
th~ ;u_t~r:.'., .. ,,.,
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Mediuni Resolution Monitors
James Beck
Greater Southern
Atlanta, Georgia
QUESTION
What is it and how does it differ from regular
low res monitors. Can a regular PCB feed a
med res monitor?
ANSWER
A "standard" monitor has specs that are
close to NTSC (National Television Stan-
dards Code) standards. That is a l 5KHz
horizontal sweep and a vertical rate of 60Hz
(non interlaced). These frequencies define
the total number of lines that are displayed
on the CRf. Then there is dot pitch, that is
the smallest discrete group ofRGB phospho-
rous that is on the face of the CRf itself. That
defines the smallest "clean" pixel that can be
enabled. The dimension of .41MM or so is a
"normal" pitch. In a game, the sync chains
and RGB outputs are designed to operate
within these specs.
MEDIUM RES
Now comes "Medium" resolution as opposed
to the above standard resolution. First you
up the horizontal frequency. That means
you get more horizontal lines on the screen
per each vertical scan. Sometimes the verti-
cal rate is increased too. 25Khz horizontal
rates are not uncommon. To take advantage
of the higher number of lines the dot pitch is
decreased so each individual pixel is
smaller. Hence, the resolution is higher. So
on and so forth, into higher and higher
frequencies.
COMPATIBILITY
The most obvious problem you see here is
that due to frequency incompatibilities you
can't put a standard res monitor into a
medium res game. Anyone who has tried
swapping with any of Atari's games like
Sprint will first notice that there are two
scrunched pictures on the screen. The
boards are putting out at a higher rate and
if the monitor does sync to one of the har-
monics then you end up with funny results.
It works in the opposite direction too. A
medium res monitor can't be properly driven~
by a standard set of boards.
RASTliiR UNE
HORl?.ONTAL SYNC
VfRTlcAL :S'iNL
BOTTOM LINE
To sum it up. the monitor and the boards
have to be matched to obtain the higher
resolutions and the matched set usually has
to remain together.
***

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