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lunedµ 20 dicembre 1999
note: all the signal & voltage present
in this procedure has to be clear and
at correct level ; compare them with a
good pcb
Supply PCB using pcb test cable code AE20101903.
Set pcb in test mode and digit 38# sim test enable
and check on J803 sim connector :
1= GND
2 = SIM VCC 5V SEE u900 ( C906 )
3 = NC
4 = RESET see CR905 , R940
5 = SIM I/O see R945 , U901 , R938.
6 = CLK see R940
Replace display
with a new one.
Is still a display
issue?
NO
END
Supply pcb using
pcb test cable code
AE20101903; is a
backlight issues
only in any leds?
YES
Replace
the faulty
one
NOTE: check if any components mentioned is correctly
positioned , has not dry joint and is not damaged . If all is ok
replace it . If problem is still the same send BOARD IN htc.
Check on J902 display connector for
1 =data DP_EN it comes from U800
YES
2= 2,7 V RESET it comes from U900
3= data A0 see R716 for missing
4= data R_W it comes from U800
from 5 to 12 = data see on C1714 to C1720
13 = 2,7 Vcc V2 it comes from C939
15 = -5 Vcc it comes from U903.
If all is ok probably U800 faulty.
ALRT_VCC = 3 V presence , if not
NO
BKLT_EN = 2,7 Vcc , in this way
on led's chatode there must be 1 V
, if not ok check for R520 presence
- MOTOROLA CONFIDENTIAL PROPRIETARY -
Dual band Taishan level 3 debug rev 1.0
YES
NO
Check, in order ,
U900 , U800 for
presence of:
14 = GND
Check on Display led's anode for
ok check Q903 and conseguently
U900 for faulty.
Check also on Q907 gate for
,else replace Q907
CHECK
CARD
Probably U800
faulty
faulty
DISPLAY
NO
BACKLIGHT
NO
Page 11
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