Service manual

15” LCD Color Monitor Sharp LL-153A
29
8.2 Trouble Shooting
8.2.1 MAIN BOARD
NO SCREEN APPEAR
Note:1. If replace “MAIN-BOARD” , Please re-do “DDC-content” programmed & “WHITE-Balance”.
2. If replace “Power Board” only, Please re-do “ WHITE-Balance”
Measured CN701 pin5,6 = 12 V?
Measured CN701 pin 9,10= 5V?
Measured U702 pin 2= 3.3V?
Measured U602 pin 2= 1.8V?
Measured CN402 pin 1/2 = 5V?
Measured CN402 pin 3/4 = 3.3V?
NG
Check Correspondent component.
Is there any shortage or cold solder?
Yes .there have OSD show
Yes, all DC level exist
Disconnected the Signal cable( Loose the
Signal cable ),Is the screen show “Cable Not
Connected” ?
Connected the Signal cable again,
Check LED status.
Led Green
Replace U402
Flash Rom
No, nothing is
Connected the Signal cable
a
g
ain
Check Power switch is in Power-on
status , and check if Power switch had
been stuck ?
Led Orange
OK, Keyboard no
Led orange
Led Green
Check the Wire-Harness from CN405
Measured RGB (R434, R435, R436 )
H,V Input at U401 pin 63,64 ,was there
have signal ?
Check Correspondent
component short/open
( Protection Diode )
NG
OK, Wire tight
Check Panel-Power Circuit Block
OK ,Panel Power
Check U401 Data-output Block
Re-do White balance adjust
OK, input Normal
NG,still no screen
OK, clock
OK
OK, U201 data
Replace Power board and Check
Inverter control relative circuit
Replace U401 (TSUM13AK)