Sharp LC-20S4U-S - 20" LCD TV, Service Manual And Parts Listparts List

Page: 30 / 84

LC-20S4U-S
30
TROUBLE SHOOTING TABLE
(Continued)
Yes Yes Yes Yes Yes Yes Yes Yes
No No No No No No No
No
No No No
Yes Yes Yes
Is there the lack of sound in any input mode (TV, video 1/2, component)?
No sound from right and left speakers
Check the following points:
1
Monitor output set at "variable"?
2
Sound volume at minimum?
3
Mute effect on?
4
Headphones connected?
Do the following and check again:
1
Set the monitor output to "Fixed".
2
Turn up the sound volume.
3
Clear the mute effect.
4
Disconnect the headphones.
Check the following points:
1
Sound heard from speakers?
2
Monitor output properly connected?
3
Mute effect on?
Do the following and check again:
1
Go to "No sound from speakers".
2
Reconnect the monitor output properly.
3
Clear the mute effect.
Is the voltage at pin (7) (power input terminal) of IC3301 as specified (about +12.5V)?
Is the voltage at pin (5) (standby control terminal) of IC3301 as specified (about +2V)? Is the supply voltage of each circuit as follows? Pin (39) of IC3201:
About +8V
Pins (65) and (66) of IC3201:
About +5V
Pins (11), (12) and (13) of IC3201:
About +3.3V
Are the following control signals fed as follows? Pin (2) of IC3201: SCL1 Pin (3) of IC3201: SDA1
Are the audio signal outputs at pins (27) (Rch) and (28) (Lch) of IC3201? Are the oscillation waveforms at pins (71) and (72) of IC3201 as specified?
Check the lines from between pins (27) (Rch) and (28) (Lch) of IC3201 to pins (4) (Rch) and (2) (Lch) of IC3301.
Check IC3201 and its peripheral circuits.
Check X3201 and its peripheral circuits.
Check the lines from pins (29) and (30) of IC2001 to pin (2) of IC3201. Check the line between pin (56) of IC2001 and pin (5) of IC3301.
Check the following points: +8V Line:
check IC3702 and its peripheral circuits as well as the line up to Pin (39) of IC3201.
+5V Line:
check IC702, Q713 and their peripheral circuits, B5V700MA line, Q3702 and its peripheral circuits, and +5V line of IC3201.
+3.3V Line:
check IC703, Q712 and their peripheral circuits, B3.3V1.2A line, and +3.3V input line of IC3201.
Check the built-in AC power supply and the line up to pin (7) of IC3301. Check the following points:
1
No TV sound: check Q3201, Q3202 and TU3401, and their peripheral circuits.
2
No Video 1 input sound: check the lines from J3402 to pins (56) and (57) of IC3201.
3
No Video 2 input sound: check the lines from J3403 to pins (53) and (54) of IC3201.
4
No Component input sound: check the lines from J3404 to pins (50) and (51) of IC3201.
Are the audio signal outputs at pins (36) (Rch) and (37) (Lch) of IC3201? Is the collector signal of Q3403 at "L"?
Check the lines from between pins (36) (Rch) and (37) (Lch) of IC3201 to pins (2) (Rch) and (4) (Lch) of J3403.
No sound from monitor output
Check the line from pin (58) of IC2001 to Q3403, as well as Q3401 and Q3402.
Check IC3201 and Its peripheral circuits.
No Audio Output