Acer X34GS Lifecycle Extension Manual page 57

5.4 LED backlight debug flow：
LED driver Debug
Check Net
19V_BLD is
19V?
Y
BU3 is damaged?
N
BD4 is damaged?
N
BR31 is open?
N
Check BU5 pin5
is high ?
Y
Backlight on?
Y
END
Replace FB36
N
FB36 is
open?
N
Y
Replace BU3
Y
Y
N
Open BR67
N
Reassemble BR67
Y
Y
Replace BD4
Replace BR31
Check NET BL_CTRL
level is high?
N
Check U12 works
Y
Replace BU5
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