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15. TROUBLE SHOOTING
In a case of trouble shooting, please try the Self-
Diagnostics operation first. If you find the specific
symptom,
go to the section
(2). If the
Self-
Diagnostics does not work, check as following first.
PREPARATION OF TROUBLE SHOOTING
Before opening the cabinet to trying the machine
repairs, it recommended
that you will take the self
diagnosis operations.
VISUAL INSPECTION
If visual
inspection
does
not reveal
an apparent
problems, use an multimeter to check that there are
no short-circuit on the board or components.
(1) Are there any loose connection cables ?
(2) Are there any discolored parts?
(3) After the AC power is turned on, are there any
parts that will be get abnormally hot, making too
much noise or gives off the smoke?
(4) Are there any loose soldering on the board?
COMMON VOLTAGE INSPECTION
With a multimeter, check the following voltage are
correct. If the some of voltage is out of the specified
voltage range, it should be adjusted by the variable
resistor.
VOLTAGE SPECIFICATION
(1) VPP
; DC +21.5V ~+22.5V
(2) VCC ;DC + 5.0V~+
5.3V
(3) VLL
; DC -25.8V ~+28.0V
(4) VF1, VF2; AC 3.8V
(5) VCM ;DC + 4.9V~+
5.3V (at AC ON)
(at AC OFF = 3.0~4.2VDC)
Note: The minimum
voltage of VCM
is should be
over than +2.5V to be hold the contents of
memory while the AC power is off.
VPP is abnormal
:
Fuse F1 blown ?
y
Fuse F2 blown ?
>
(a) Check L1, C1 or Power
Transformer.
88,/ (b) Replace F1 and check F141
again with no connection
of CP3
(a) Check Q1 and D1-D4
(a) Check all wiring.
(b) Find a short-circuit
place on the M1 PCB.
-—-27-
VLL or VF1/VF2 is
b
I
(a) Check L1, C1 or Power
Transformer.
(b) Replace F1 and check
F1 again with no
connection of CP3.
(a) Check Q1, ZD2, T1
(a) Check ZD1 if the VF1
or VF2 is abnormal.
(a) Check
D9.
(b) Check Ni-Cd battery.
(c) Find a short-circuit
place on the M1 PCB.
s
Plug the AC cord
(a) Check D7
(a) Check IC7
(b) Find a short-circuit
place on the M1 PCB.
Make sure the
display cables are
connect firmly
(a) Check the soldering
of M3 or M4 PCB.
(b) Check display tube.
(a) Check Power supply
(a) Check the segment/
digit signals from the
IC1.
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