Toshiba SD-V55HTSU Circuit Diagrams page 16

(2) No Sound
No Sound.
Check the Vcc of TU701 Pins3, 14.
Check the Tuner SiF signal at IC801
Pin57.
Check the Audio of IC801 Pins78, 80.
Check the Signal flow from IC801 Pins78,
80 to JK601 Audio out(L), (R)
YES
YES
YES
YES
NO
NO
Check the Tuner SIF of TU701 Pin13.
NO
1. Check the Vcc(5.3VA, 9V) of IC801
Pins3, 5, 36, 54.
2. Check the IIC Clock and Data at IC801
Pins37, 38.
3-15
Check 5.2V, 33V Line.