U503 Abnormal; U501 Abnormal - LG SB74 Service Manual

11. U503 ABNORMAL

Check the power supply to U503 pin24
Check the SCL/SDA data of U503 pin25, 26
Check the control function
OK

12. U501 ABNORMAL

LCD display check
YES
Check the power
supply to U501 pin7
YES
Check U501 pin1 CS
pin3 WR, pin4 data
YES
OK
13. U101 FM TUNER MODULE
Check the power supply of U101 pin3
Check TU-SCL, TU-SDA
Check the operation
OK
YES
YES
YES
NO
Refer to power supply
NO
Check MICOM U603 pin71
CS, pin72 DAT, pin73 WR
YES
YES
YES
NO
Refer to power circuit troubleshooting
NO
Check JK601 pin47, 48 Vol_CLK/Vol_Data
NO
U302 3.3V
YES
NO
NO
NO
Check JK600 pin24, 26
3-6
Check or replace U503
Replace MICOM
Check Q305 B "High"