Blu LIFE 8, Руководство по обслуживанию

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3.2.2 TX circuit troubleshooting
Key parameters of TX circuit is “MAX power”, “TX current”, “Time mask”, “phase error”,
“frequency error” etc.
Following is normal analysis of circuit:
Confirm the instrument for analysis is OK.
a. Set up the voltmeter (power supply, voltage=3.8V-4.2V) and oscillograph.
b. Set the right frequency and sweeping time on spectrum analyzer or use CMU200 and
agilent8960.
c. The phone connecting to computer, power on and use the tool(META) control the
phone, set up the channel and power level(for example, GSM:CH=62 or Freq=902.4MHz
Power Level=5.DCS: CH=700 or Freq=1747.4MHz Power Level=0 ), control the phone to
transmitting state.
Note: test on a good radio to get reference signal when you don’t know if the signal is right.
You can depended on your experience to repair, unlucky, if you not enough experience,
you’d better follow this document.
Step1. The phone in transmitting state, first, observe whether the current is raised, if no,
that means PA don’t working. You must check the PA working voltage and control signal
PAEN
Step2. If the output signal from transceiver IC is good, then measure the TX signal at PA
input pin.
Step3. If the input signal is good, then measure the output signal from PA. Measure the
output signal of PA, if the signal is not good then check PA and parts around it Check the
voltage VBAT and control signal VAPC and PAEN and so.
Step4. check RF connector then measure TX signal at antenna point at last.