Nokia Customer Care
Appendix A: RF Troubleshooting
A-94
Company Confidential
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Connect the probe to R7519.
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TX VCO control voltage VC should be constant DC-voltage between 0.7 - 3.8 V. DC voltage level
should change if TX channel is changed. VC is lower on lower channels and higher if higher
channel numbers are used.
4.1.3.1.2.1 VCP2-voltage ok?
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WCDMA transmitter has to be active before VCP2 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 C2221 (or C7550).
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VCP2 voltage should be about 4.75 V.
4.1.3.1.2.1.1 C7550 short-circuited?
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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 use an ohmmeter to check that C7550 is not
short-circuited. If short-circuit is found replace the capacitor mentioned above. If this does not
help go to the next step.
4.1.3.1.2.1.2 Retu ok?
4.1.3.1.2.1.3 Vinku (N7501) ok?
4.1.3.1.2.2 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.
4.1.3.1.2.2.1 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.
4.1.3.1.2.2.1.1 Desolder R7503. Is VREFRF01 voltage still wrong?
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Remember to solder a new component to R7503 pads after measurement.
4.1.3.1.2.2.1.1.1 Capacitors C7518, C7520 and C7570 working correctly?
