Appendix A: RF Troubleshooting
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A-81
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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.
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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.
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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.
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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
levels.
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Connect the probe to C7576 pad. Notice: C7576 is a non-assembled component so the probe
should be connected to the pad that can be still found from the PWB.
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WCDMA PA bias current Icont_11 should look as a constant 2.5 - 2.6 V DC-voltage with all power
