Nokia Customer Care
Appendix A: RF Troubleshooting
A-110
Company Confidential
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2005 Nokia. All rights reserved
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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.
4.3.1.5 Replace SMPS N7504
4.3.2 Does WCDMA PA (N7503) get correct 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
levels.
4.3.2.1 Vinku (N7501) RB_EXT voltage ok?
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WCDMA transmitter has to be active before Vinku’s RB_EXT voltage can be measured. Procedure is
explained in section “Transmitter troubleshooting”.
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Measurement can be done with an oscilloscope and a probe.
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Connect the probe to R7521.
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RB_EXT voltage should be 1.325 – 1.375 V.
4.3.2.1.1 VREFRF01-voltage ok?
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Measurement can be done with an oscilloscope and a probe.
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Connect the probe to R7503.
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VREFRF01 voltage should be 1.325 – 1.375 V. Typical value is 1.35 V.
4.3.2.1.1.1 Desolder R7503. Is VREFRF01 voltage still wrong?
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Remember to solder a new component to R7503 pads after measurement.
4.3.2.1.1.1.1 Capacitors C7518, C7520 and C7570 working correctly?
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Check that components are in place and solder joints are ok
