Trouble Shooting - Dell E156FPc Service Manual

9.2 Trouble shooting

9.2.1 Main Board
No display
Measured CN701 pin5/6 = 12 V?
Measured CN701 pin 9/10= 5V?
Disconnected the Signal cable (Loose the
Signal cable), Is the screen show Block
WRGB color bars?
Connected the Signal
cable again Check LED
status.
Check the Wire-Harness from CN101
Check Panel-Power Circuit Block
Check U401 Data-output Block
Replace Inverter board and Check
Inverter control relative circuit
Re-do White balance adjust
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"
OK
NG
Check Power switch is in Power-on
Orange
status, and check if Power switch had
been stuck?
OK, Keyboard no stuck
Green
OK, Wire tight
enough
OK, Panel Power OK
OK, U401 data OK
Check main board Power; is there DC level
NG
output? Check U701 pin 2= 3.3V? U702
pin 2= 1.8V? Is there any shortage or cold
solder?
Connected the Signal cable again,
OK
check LED status.
Measured RGB (R434, R435,
R436,) H/V Input at U401 pin
89,90, Was there have signal?
OK
Measured Crystal X401
OK
Replace U401 (GM2621)
OK
40
Dell E156FPc
Green
Replace U401
Scalar IC
Orange
Check
Correspondent
component
short/open
(Protection Diode)
NG