COPYRIGHT © 1995 MERIT INDUSTRIES, INC.
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Technical Service Bulletin
TSB2A 5-25-95
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5/30/95
merit industries, inc.
Problem:
Prevent CPU board malfunctions caused by electrostatic
discharge.
Games affected:
All Megatouch II countertop games with CRT-260 CPU
board and PCB mounted touchscreen controller. Effects
model number G20-100-001, serial numbers 348702
through 350000 and 380001 through 381750.
Symptoms:
Game locks up, or does not power up at all.
NOTE: If game
does not power up at all, damage may have already occurred.
Call Merit Technical Service (1-800-445-9353).
Cause:
The touchscreen controller board is not adequately
grounded to dissipate electrostatic discharges.
Additionally, the CPU's reset signal is unnecessarily
connected to the controller and may provide a path for a
static shock to damage the reset circuitry.
Solution:
Cut the reset line to the TTL controller board and attach
extra ground braids to the chassis.
Tools:
Materials:
Screwdriver
(2) - 7” 14 (or 16) AWG insulated wire
Wire cutter
(1) -11” 14 (or 16) AWG insulated wire
Pliers or crimper
(1) - #6-32 x 3/8” machine screw
(4) - #6-32 x 1/2” machine screw
(1) - #4 external tooth lock washer
(4) - #6 external tooth lock washers
(2) - #6-32 kepnut
(6) - #6 or #10 ring lugs
Instructions
1.
If you have ring lugs, attach one to each end of the three pieces of wire. If
you do not have ring lugs, simply wrap the wire around the screw when
you see the term “ring lugs” used in this bulletin.
2.
Open the rear door and slide the CRT-260 into its service position.
COPYRIGHT © 1995 MERIT INDUSTRIES, INC.
TSB2A
Technical Service Bulletin
2
3.
Remove the ribbon cable attached to header J6 (2 x 7) on the CRT-260
board and cut Pin 7 on J6. Header J6 can be seen in Figure 1.
Reattach the ribbon cable to header J6. Make sure that the blue edge of the
ribbon cable is on the left, corresponding to Pin 1.
4.
Untie the green, gray and orange wires tie-wrapped to the touchscreen cable
connector. Retie the orange cable to the touchscreen cable connector.
Strip the insulation from the gray and green wires to reveal 1/2” bare wire and
twist them together.
Connect them to the “ground” on the power supply.
5.
Remove the TTL controller board from the three standoffs holding it above
the CRT-260 board.
Using a #6-32 x 3/8” screw and a #6-32 kepnut, attach one end of the 11”
wire to the unused, plated-through hole on the TTL controller board.
Make sure to put the ring lug on the bottom of the board and screw
from the top.
Attach the other end to the chassis as shown in Figure 1. Use a #6-32 x 1/2”
and a #6 lock washer. Make sure that the washer is between the ring
lug and the chassis.
Replace the TTL controller board by carefully pressing the board back onto
the standoffs.
6.
Remove the thumbscrew securing the power entry/fan/speaker assembly and
pull out the assembly.
Attach the ring lug on one of the 7” wires to one of the studs that mounts the
line filter. Put the #4 lock washer between the lug and filter. This can
be seen in Figure 1, detail C.
Using a #6-32 x 1/2” screw and a #6 lock washer to connect the free end of
the wire to the chassis as shown in Figure 1.
7.
Referring to Figure 1, detail B, remove the screw securing the left-hand side
of the lid hinge to the chassis. Use a #6-32 x 1/2” machine screw, a #6
external tooth lock washer and a #6-32 kepnut. Be sure to attach the
ring lug on the underneath side of the lid.
8.
Slide the CRT-260 back into the cabinet and close the rear service door.
9.
All parts mentioned in this bulletin are available in a kit from Merit Industries.
Call your distributor for details.
COPYRIGHT © 1995 MERIT INDUSTRIES, INC.
TSB2A (FIGURE 1)
Technical Service Bulletin
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