GX20
2 – 53
CONFIDENTIAL
9. Back light does not turn on.
Do the keypad tones and ring tone sound from the speaker?
Jumper (TPB333 to CN305 36, 37 pin) or Relay FPC_A,
CN305, CN201 defective.
Voltage of VBAT_AP applied to FS401?
Jumper (CN201 2 pin to FS401) defective or defective mount-
ing.
Defective mounting or blowout of FS401.
Voltage of VBAT_AP applied to IC404 6 pin?
Apparance, mounting and continuity properly given to FS401
(Fuse)?
C465 and C466 defective.
Only external display back light.
Which display does not light up? Main or external?
(To page 2-54)
Is the main display back light set to ON?
ON Setting by the following menu.
Settings
→
Phone settings
→
Main display
→
Back light
Does the back light turn on?
Nondefective.
Are appearance and mounting of CN402 properly given?
CN402 defective.
Back light FPC defective or CN402 defective.
Dirt and foreign matter detected at the back light FPC termi-
nal? Back light FPC properly inserted in CN402?
Clean the back light FPC and insert it again. Then does it light
up?
Nondefective.
Voltage of 13 to 24 V applied between TP428 to TP429?
Back light FPC defective.
IC104 or Jumper (IC104 42 pin to IC404 4 pin) defective and
defective mounting.
Does the back light slightly light up as the auxiliary light?
Is the pulse shape sent to IC404 4 pin? (Don’t hold to Low?)
IC404, L410, L411 and D413 defective.
Voltage of 3 V applied to Q404 gate (G) terminal?
IC104 defective.
Voltage of less than 10 mV applied to Q404 drain (D) (R453
side) terminal?
Q404 defective. (0.95 mV at drain terminal)
R453, R437 and IC404 defective.
NO
YES
NO
YES
NO
NO
YES
YES
H
Only main display back light
or both displays' back lights.
NO
YES
NO
YES
When the external display
back light does not light up.
(To page 2-54)
H
NO
YES
NO
NO
YES
YES
YES
NO
NO
NO
YES
YES
NO
YES
NO
YES
Содержание GX20
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