LG MICRO Hi-Fi SYSTEM Service Manual page 18

7. FLD DISPLAY PART CHECK
FLD DISPLAY CHECK
YES
Check
P7904 1,2,3 power
YES
F1+,F2-both terminals:over 4.4V
Check power VKK:over -32V
YES
Check
P7904 connection
condition and power F1+,F2-
both terminals:over 4.4V
check power VKK:over 32V
check 5pin:5.6V
YES
Check
IC301 PT6302
power 48pin VKK:-32V
57pin +5V
YES
IC100
check→IC301
data communication
pin pin
26pin→55pin DO
28pin→54pin CLK
27pin→53pin STB
5pin→52pin RST
YES
FLT light on?
YES
OK
NO
Refer to SMPS
troubleshooting
Check P7904 assembly
Check
NO
power of each pin
OK
NO When 5V fails,check D303 SR35
input and output power
Check the related part
OK
IC100 27pin
NO
28pin→CLK
check data output
Check 26 PIN→DO→DATA input
Check the related part
OK
3-5
YES
NO
YES
YES
NO
YES
→ STB
YES
YES
NO
YES
Replace the related part
Replace the related part
Replace the related part