LG FFH-3765MVA Service Manual page 21

IC701, IC751 Troubleshooting
Check the signal input of Pin 3
YES
Check the High(5V) of Pin 9, 10
YES
Check the Pin 8, 15 (-), & Pin 7, 13 (+)
YES
Check the signal output of Pin 14
YES
END
FM (TUN101)
Check the +12V input of TUN101 B+ 6
YES
Check the "High" Voltage of TUN101 VT 5
YES
Check the OSC waveform of TUN101 Pin 8
YES
Refer to "IC102 Troubleshooting"
NO
Refer to "Muting Troubleshooting"
NO
Check the +5V of D791
Check the PATTERN
NO
Refer to "Power Circuit Troubleshooting"
NO
Refer to "SPK Relay"
Check the 12V of Q102 "E"
YES
Check the GND of IC103 Pin 7
YES
Replace the Q102
Replace the TUN101
Replace the TUN101
- 2-15 -
NO
Refer to "IC301
Troubleshooting"
YES
NO
Refer to "Power
Circuit Trouble-
NO
Troubleshooting"
shooting"
Refer to "IC103