Elo TouchSystems ET1587C - 2. The OSD is malfunction

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C. CPU Service Procedure
1. The CPU is malfunction.
2. The OSD is malfunction.
3. The data message could not be stored by E2PROM.
4. The CS signal from CPU is not working properly.
5. During mode change, there is a annoying picture appear on screen.
Solutions:
1. The CPU is malfunction
Note:
The CPU mal function is usually caused by the pin 4 not turning to low at power on
(this step will initialize the CPU address to ZERO), and then pin 4 return to high state (at
Check the
pin5=5V
Check pin4
AtU101=5V
Put the test probe
on the pin 4
Turn the monitor off,
then turn on
Make
sure if pin 4 change
from low state to
high state
Check
pin7, pin8 at U101 if
there is 12MHz sine
wave oscillation
Check the front
panel
Yes
Yes
Yes
Yes
Check power supply
circuit area
No
END
No
If pin 4 less than 3V,
check the components
around pin 4
No
No
Check the components
around pin 7, 8
END