Fld Display Check - LG CM4740 Service Manual

AUDIO ELECTRICAL TROUBLESHOOTIHG GUIDE

4. FLD DISPLAY CHECK

FLD DISPLAY CHECK
YES
Check
CN501 Pin13,14,15 input
voltage.
YES
Check if both end voltage
of FL+, FL- are over 2.9 V
VKK : over 25.6 V.
YES
Check CN301
connection and power
Pin1, 2, 3(FL+, FL-, VKK),
Pin8(5.6 V).
YES
Check
IC301(MC3401) voltage
Pin30 VKK: -25.8 V
Pin13, 43: 3.3 V.
YES
Check
IC501->IC301
data communication
STB/ DATA/ CLK
YES
FLD light on?
YES
OK
NO
Refer to SMPS troubleshooting.
NO
Check CN301 connection.
YES
Check each
Pin voltage.
YES
OK
NO
If voltage is not 3.4 V.
YES
Check IC301.
YES
OK
NO
Check input data
IC501 Pin F1,F2,G1.
YES
Check output data IC501 Pin D2.
YES
Check IC501
YES
OK
3-21
NO
NO
.
Replace IC301.
Replace IC501.