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STAR*TECH Journal
Hantarex
Zenith
MTC9000
9-227-01
Excessive
Width
Vertical
Foldover
JoeBurtzel
Music Service, Inc.
Marshall, Minnesota
April 1992
SNK
~
Neo•Geo
Interm.ittent
Graphics
Sam Cross
Godwin Distributing
N. Little Rock, Arkansas
Dan Doctor
Inter Provincial Amusement Co.
Etobicoke, Ontario, Canada
SYMPl'OM
SYMPI'OM
PRoBLEM
Cannot reduce width down far
enough to view entire picture.
Vertical foldover.
PROBLEM
Check C2103 100uf/35v radial
capacitor. Replace and verify.
So far we have had a couple of 4
slot Neo Geo's come to our shop
with graphics problems. Both
games work fine for a few hours
and then suddenly the screen
would be missing lines of graph-
ics.
CAUSE
This particular monitor I encoun-
tered was in a Taito Chase HQ.
PRoCEDURE
After confirming that my B+ was
running at+ 130vdc, I went hunt-
ing in the width coil circuits and
found that C42, a 4. 7uf @ 50v
electrolytic, was open.
Replacing C42 brought the width
down and was then completely
controllable by the Horizontal
Amplitude Control RV 4, located
on the stand up PCB with all of
the other vertical and horizontal
controls.
CAUSE
Upon inspection with a high~
power magnifying glass, I found
some legs on the custom chips
were lifted slightly off the runs.
(Cold solder joints)
WellsGardner
K4914
Horiz Tear
SOLUTION
Applying pressure to the legs
with a pair of tweezers while
heating up the joint with a fine
tipped soldering iron will
reattach them properly to the
board.
l..oCATION
C42 is located inside of the big
metal heat sink, to the left of the
flyback, and requires the use of a
needlenose pliers to remove and
replace.
Phil Ivany
Regent Vending & Amusements
Ottawa, Ontario, Canada
PROBLEM
Horizontal tear when the moni-
tor is cold, but seems to correct
itself when it warms up.
SOLUTION
Replace C354 (47uf@25v). Read-
just horizontal hold and horizon-
tal shift to properly center the
picture.
NOTE
Extreme care must be taken
when doing this procedure.
Double check all connections to
make sure you have not shorted
any legs or traces together.