LG LX-D2640 Service Manual page 10

Muting circuit Troubleshooting (if MUTE)
Q700, Q750, Q720, Q770, Q730 Base "LOW"
YES
Q700, Q750, Q720, Q770, Q730 collector "Low"
YES
MUTE
No sound
Ic702 pin 4, 6 signal output check
YES
Realy connected check
ON
YES
Speaker connected check
IC701 pin3, 4, 15 signal output check
YES
Speaker connected check
ON
Q783, Q784, Q785 "E" High check
ON
IC703 5, 6, 7 pin High check
PATT check
ON
Each appropriate TR replacement
ON
IC702 pin10, 14 pin signal input check
R781 voltage check IC702 pin12 "High" check
YES
IC702 power check replacement
Q780 Base "H" check
ON
IC701 pin8, 12, 13 signal input check
IC701 pin10 "High" check
IC701 Power check replacement
- 2-3 -
YES
ON
YES
IC703 Troubleshooting check
YES
ON
YES
ON
YES
ON
YES
Q702 Base "H" check
Q720/Q770/Q730
Base "L" check
Q702 Base "H" check