Back Light Does Not Turn On - Sharp TQ-GX30E Service Manual

GX30

10. Back Light does not turn on.

Is VBAT voltage applied to C701?
Which back light does not turn on, Main or External?
Is back light setting for External Display set to On?
Is CN705 in good appearance and mounted properly?
Is the contact point of back light FPC clean?
Is back light FPC properly inserted to CN705?
Is 13 - 24 V applied between TP710 and TP711?
Are C790, C791, C702, C707, C713, R718, and D702 in good
appearance and mounted properly?
IC707, and R707 are defective.
Is back light setting for Sub Display set to On?
Is 7 V applied between LED703 anode (A) terminal and
LED704 cathode (K) terminal?
LED703 and LED704 are defective.
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CONFIDENTIAL
YES
Main Display only or both.
YES
YES
YES
NO
YES
C
YES
YES
manuals search engine
FS701 is mounted improperly, or the fuse is brown.
Is fuse (FS701) in good appearance, mounted properly, and is
NO
there conduction?
C701, C703, and L701 are defective.
External dis-
play only.
C
Go to the setting as follows and set it to On:
NO
Settings → Phone settings
Main display → Back light
NO
Does it turn on?
Not defective.
NO
CN705 is defective.
Back light FPC or CN705 is defective.
Clean back light FPC and insert it again. Does it turn on?
NO
Not defective.
YES
Back light FPC is defective.
C790, C791, C702, C707, C713, R718, and D702 are defec-
NO
tive.
Go to the setting as follows and set it to On:
NO Settings → Phone settings
External display → Back light
NO
Does it turn on?
Not defective.
IC707 is defective or mounted improperly.
NO
2 – 58
NO
YES
YES
NO
YES
YES