U8950 Maintenance Guide V1.0
9 Maintenance Records During Verification
2012-10-22
Huawei Proprietary and Confidential
37
Stage
Station of Fault
Faulty Item
Symptom
Solution
V4
MMI
MMI02A SIM
card detection
failure
The SIM card was
worn, resulting in
probabilistic poor
contact.
The SIM card voltage, clocks, reset
signals, and signal lines were all
proved normal. The SIM card was
removed and inserted again and the
test then passed. However, failure
was detected during multiple tests
with a low probability. The SIM
card for test was found of several
abrasions. It was recommended that
this card be replaced.
VN1
MMI
MMI09A
interface
malfunction
The interface J903
connecting to the
antenna board was
poor soldered and
could be easily
tilted.
The interface was re-soldered and
the test then passed.
VN1
Assembly
The shielding
cover could
not be
installed.
The shielding cover
was over-glued or
the silica gel
dispensing line was
defective, resulting
in overflow of the
glue from the holes
on the shielding
cover to the gaps.
The assembly was
then hindered.
A photo was taken to confirm with
the PE. The overflow of glue was
heated using the heat gun and then
cleaned using a pair of nippers.
VN1
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interface after
the loading
VPH_PWR,
VREG_S2,
and U401 were
short-circuited.
The PMU chip and relevant
capacitors were removed and the
chip U401 was determined to cause
a short circuit. The chip U1002 was
short-circuited during the SMT.
pPMU
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The resistance of
VPH_PWR was 0
ohm. The
chip U1002 was
short-circuited.
The problem was proved to result
from short circuits of U1002
and U1402 and reported to the R&D
department for further analysis.
VN1
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interface after
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The resistance of
VPH_PWR was 0
ohm. The
chip U1002 was
short-circuited.
Bridging occurred
during the SMT.
After U1002's shielding cover was
removed, the solder points of
VPH_PWR were found bridged,
resulting in a short circuit. This
problem was reported to process
personnel for further analysis.