No Sound
Whether the audio signal input
Check external
Audio equipment
check the 7th pin of U21/TDA1517P,
Whether there is more than 11V power supply
N
Y
Y
N
check the 8th pin of U21,
Whether there is more than 11V power supply
Repair the U21 power supply
Whether Volume, MUTE setting is normal
Reset the
setting
U1's 11th and 6th pin Whether there is signal output
Y
N
Check external
speaker
N
Y
Repair D47 or R257,
And whether Q28 damage
Check the 50th, 51th pin of U14,wheath have signal output
Y
N
Y
N
Whether U14 haw signal input
Check the circuit from U14 to U21
五
五
五
五、
、
、
、Audio Trouble
Audio Trouble
Audio Trouble
Audio Trouble（
（
（
（no sound
no sound
no sound
no sound）
）
）
）
