Fukuda Denshi FCP-7101, Service Manual

Page: 27 / 170

Maintenance
2 - 7
●
LCD does not display or display is abnormal.
Item to Check Method of Checking and Corrective Action Place to Check
Contrast
Operate the contrast control knob to adjust the LCD
brightness.
Contrast adjusting knob
REFERENCE
P1-2
Connector Verify that the flat cable of the LCD unit and P1 on
the KEY
•
LCD I/F board is securely connected.
Verify also that the flat cable is inserted in the
correct direction and is free of cuts and separation.
Flat cable of LCD unit and P1
REFERENCE
P5-32
Power supply Check the voltage for the main board.
･ V
SS
: P1 (11 and 14 pins) GND level
･
V
DD
: P1 (10 pins) +5V
If V
SS
or V
DD
is abnormal, refer to the section of +5
V in "Troubleshooting related to supply voltages".
P1 pins 11,14
P1 pins 10
REFERENCE
P2-4, P5-32
Control signals Verify that LCD control signals FLM,CL1,CL2 and
D0-3 are not at the H or L fixed levels.
Verify also that the DISPOFF* signal is at the H
level.
The LCD module is controlled by IC7(CPU); thus, if
the control signal is abnormal, IC7 is likely to be
defective. P1 Pins 1 to 4 and pins 6, 8, 9
IC7
REFERENCE
P5-28, 32
Liquid crystal voltage
V
EE
Check the voltage on P1 pins 12.
･
V
EE
P9 (pins A24, A25) V
EE
.
V
EE
is a liquid crystal drive voltage. The LCD
contrast is controlled in terms of this voltage. The
voltage depends on the operation circumstances.
Operate the contrast adjusting knob to see if the
voltage is b21 and +24 V.
If V
EE
is abnormal, refer to the section of V
EE
in
"Troubleshooting related to supply voltages". Also
check the action of Q1 area.
P1 pins 12
Q1
REFERENCE
P2-4, P5-32
P5-27