Radio Frequency; Gsm Calibration During Production; Gsm Afc Calibration; Gsm Rx Path Loss Calibration - Lenovo S930 Service Manual

LENOVO S930 Cellphone Service Manual

4 Radio frequency

4.1 GSM calibration during production

4.1.1 GSM AFC calibration

⚫
Problem: AFC calibration failed.
⚫
Reason: Connections of RF test cable are not reliable during the calibration. TCXO is fitted
reversely or has a dry joint problem. Receiving channel is open.
⚫
Troubleshooting:
Check whether the crystal (U2104) is fitted reversely or
has a dry joint problem.
Is the separate calibration of GSM
Rx Path Loss successful?
Replace main chip MT6166(U2101) or
MT6582(U1201).
⚫
Note: Normally you need to re-calibrate the corresponding components after the replacement.

4.1.2 GSM Rx Path Loss calibration

⚫
Problem: Rx Path Loss calibration failed.
⚫
Reason: During the calibration, connections of RF test cable are not reliable; components in
receiving channel (such as RF connectors), PA module, saw filter and peripheral capacitors have
AFC calibration
failed.
Check whether
connections of RF cable
and fittings are reliable.
Y
N
N
N
Re-connect and
calibrate.
Y
Y
Analyse the Rx Path Loss
problem at first.
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Re-solder.