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Appendix A: RF Troubleshooting
Measurement can be done with an oscilloscope and a probe.
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Connect the probe to C7591.
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Vcontrol signal should be constant DC-voltage. Voltage level should change if TX power is changed.
Vcontrol is lower on lower power levels and higher if higher power levels are used.
Vcontrol should be about 570 mV with power level +10 dBm, about 2.0 V with power level
•
+21 dBm and about 200 mV when power levels below 0 dBm are used. NOTE: Perform WCDMA
transmitter tests with > 0 dBm power only in RF shielded environment.
4.1.1.3.2.4.1 Is there correct DET_SW_W –voltage coming from Vinku ASIC (N7501)?
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Measurement can be done with an oscilloscope and a probe.
Connect the probe to C7586.
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Voltage level should be about 2.78 V.
4.1.1.3.2.4.1.1 Replace Vinku (N7501)
4.1.1.3.2.4.2 Check WCDMA power detector components – In place and value correct?
Components L7514, C7585, V7500, R7526, C7586, R7527, C7587, C7590, R7529,
R7530, C7591, R7531 and C7592.
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Check that components are in place and solder joints are ok
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Disconnect the power supply from the phone and check resistors resistance values with an
ohmmeter
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Use an ohmmeter also to check that L7514 is conducting DC.
4.1.1.3.2.5 Replace SMPS N7504
4.1.1.3.3 Does WCDMA PA (N7503) get bias currents Icont11 and Icont12?
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WCDMA transmitter has to be active before measurements. Procedure is explained in section
"Transmitter troubleshooting".
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Set TX power level to -40 dBm (Set start level to "-40.0" in phoenix)
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Measurements can be done with an oscilloscope and a probe.
Connect the probe to C7579
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WCDMA PA bias current Icont_12 should look as a constant 2.5 - 2.6 V DC-voltage with all power
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levels.
Connect the probe to C7576 pad. Notice: C7576 is a non-assembled component so the probe
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should be connected to the pad that can be still found from the PWB.
WCDMA PA bias current Icont_11 should look as a constant 2.5 - 2.6 V DC-voltage with all power
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Troubleshooting
