Sharp Aquos LC 26D7U, Service Manual

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49
LC-26D7U
LC-32D7U
LC-37D7U
TROUBLE SHOOTING TABLE
YES
YES
YES
YES
NO
YES
NO
YES
YES
NO
NO
NO
NO
NO
<Power supply>
The unit does not start even if the power is turned on (the front LED does not light up).
Is the power supply cord properly connected to the main unit?
Is the output voltage of BU+6V line (pin 5 of PO terminal) normal? In stand-by, is a voltage of about 170 V applied to C734?
Check the switching power supply circuit of 13V line.
(T701, T702, Q706-714, PC703-704, D708-716, IC702, L709,
Q733-736, D734-735, etc.)
Check the oscillator side for each DC/DC converter and rectifier
side on the secondary side.
Remove the broken part or short-circuit and check again.
Is voltage (approx. 380V) generated at C709/C710/C832 (*3) when
powered on?
*3: for 37" only
Is the 13V line normal immediately after powered on?
Is each DC/DC converter output normal?
Replace each DC/DC converter. Check peripheral circuits and
each line.
1) URB6V(IC707)
4) BS10V(IC708)
2) UR10V/UR31V(IC709) 5) UR6V/5V (IC707, IC713)
3) 1.8V/3.3V (IC711, IC710)
Reconnect the wire harness, FFC, etc. and check again
.
Check the switching power supply circuit of 380V system.
(L703, IC701, Q701-5, Q715, Q716, D705, D797 (*4), TH701, etc.)
*4: for 37" only
Reconnect the power supply cord and turn on the power.
Are F701, F702, and F703 normal?
If fuses burn out when F701 and F702 are replaced and the
power is turned on again, replace VA702, VA703, D701, D796
(*1), L703, TH703 (*2), Q701, Q702, and IC701, and recheck
them.
*1: for 37" only *2: for 32/37" only
Check the oscillation side (primary side) and the commutation
side (secondary side) of the BU6V system power supply circuit.
Is there any broken part or short-circuit on BU6V line?
Are the wire harness, FFC, etc. in the set connected properly?
•
Power switch: Top panel
(Main) Power (DC cutoff: Detected by microprocessor)
[Scheme of power supply system]
POWER-KEY
Seine
Main
Monitor microprocessor Backup
YES
YES
YES
[(Main) Power OFF sequence]
1) (Main) Power OFF (DC switch)
PS-ON