LG FLATRON L4200A Service Manual page 25

POWER CHECK OF MSP3420G(U503) : L505(8V), L508(5V), R509(5V)
POWER CHECK OF TPA3004(U505) : C510(18V)
CHECK SOUND OF VCR,DVD,PC
(TV)CHECK OF CONNECTION OF
TUNER AND ANTENNA
CHECK MSP3420G(U503) I/O SIGNAL
CHECK TPA3004(U501) I/O SIGNAL
CONNECTOR CHECK
4. SOUND TROBLE SHOOTING
NO SOUND OUTPUT
NO INPUT SIGNAL
NO OUTPUT SIGNAL
NO INPUT SIGNAL
NO OUTPUT SIGNAL
NO INPUT SIGNAL
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CHECK SOUND INPUT
=>PC SOUND(J804)
=>VIDEO, DVD, DTV SOUND
(RED, WHITE OF J809, J808)
CHECK THE PERIPHERAL IC OF
MSP3420G(U503)
CHECK THE PERIPHERAL IC
OF MSP3420G(U503)
CHECK THE PERIPHERAL IC
OF TPA3004(U501)
CHECK CONNECTION OF
SPEAKER ON MONITOR