Huawei U8950 Maintenance Manual page 64

U8950 Maintenance Guide V1.0
Working Principle
In the above figure, the 19.2 MHz clock outputs to the PM8029 and RTR6285A. The
TPK_LO_ADJ controls the clock output precision. The TPK_LO_ADJ has two filtering
circuits: from R204 to C232 and from R3101 to C3101, which outputs to the main chip
through the PM8029 as the system main clock.
The 32.768 kHz oscillator signal outputs to the PM8029 and is provided to the system.
Troubleshooting Process
Failures:
The phone cannot be powered on or frequently freezes. Check whether 32.768 kHz, X301,
and U3101 have no output, and whether the output is stable.
Solution: Replace X301 or U3101. If the problem persists, replace PM8029.
2012-10-22 Huawei Proprietary and Confidential
10 Principles and Failure Analysis
60