Star Tech Journal

STAR*TEcH
September 1 996
Journal
MERIT
TOUCHSCREEN CONTROLLER MODIFICATION
Customer Service
Merit Industries
Bensalem, Pennsylvania
PROBLEM
UART chip blowing out.
GAMES AFFECTED
All video games using the CRT-
260 board.
SYMPrOM
Touchscreen controller failure.
CAUSE
Electro-static discharge feeding
through the +SV line.
I
INsTRucr10Ns
I
1. Tum off the game and unplug
ft from its power source.
2. Open the CPU section door
and slide the CRT-260 into its
service position.
3. Disconnect all wires, harnesses
and ground straps attached to the
CRT-260 and its daughter
boards.
4. Remove the CRT-260 from the
cabinet and tum it over to the sol-
der side.
5. Place a piece of kapton tape
between the pin rows for U 41 ( on
the solder side), covering the
traces and vias located between
the pins. (This is to prevent the
suppressor diode you are about
to install from shorting any ex-
posed vias.)
plane). Make sure that the cath-
ode end of the diode ( the end
with the band) is attached to the
UART pin and the anode end is
attached to the ground.
8. Using silicone, seal the diode
in place.
9. Place the CRT-260 back into
the cabinet and reconnect all
wires, harnesses and ground
straps. Close the CPU section
door.
10. Plug in the game and power
up.
6. Attach a 22 A WG wire from
Pin 12 of U41 (chip select O and
chip select 1 of the UART) to the
+SV pin of the capacitor at CX41
(when viewed from the solder
side, the +SV pin of CX41 is on
the left).
7. Attach a transient suppressor
diode from Pin 13 of U41
(UART) to the ground pin of
CX41 (when viewed from the
solder side, the ground pin of
CX41 is on the right; you can see
that it is connected to the ground
CX41
GROUND
,,,-GROUND
J.>LANI:
• 01101
PIN 13
Pl.-kaplon
tapabetMen
the rows pill$ _
or
50000f95
___.
Figure 1 • Solder side CRT-HO