Nokia Customer Care
Appendix A: RF Troubleshooting
A-86
Company Confidential
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2005 Nokia. All rights reserved
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Set TX power level to -50 dBm (Set start level “-50” to Phoenix)
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Measurement can be done with an oscilloscope and a probe.
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Connect the probe to C7549
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TX control voltage TXC should be constant DC-voltage between 0.1 - 2.3 V. Voltage level should
change if TX power is changed. TXC is lower on lower power levels and higher if higher power
levels are used.
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TXC voltage should be about 1.0 V with power level -50 dBm and about 1.5 V with power level
0 dBm.
4.1.2.1.4.1 R7514 resistance value correct?
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Check that the component is in place and solder joints are ok
•
Disconnect the power supply from the phone and check R7514 resistance value with an ohmmeter
4.1.2.1.4.2 C7549 ok?
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Check that the component is in place and solder joints are ok
•
Disconnect the power supply from the phone and use an ohmmeter to check that C7549 is not
short-circuited.
4.1.2.1.4.3 Retu ok?
4.1.2.1.5 Does Vinku (N7501) WCDMA-modulator get correct supply voltage (VREG2)?
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WCDMA transmitter has to be active before measurements. 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 R7520
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DC voltage level should be 2.65 – 2.86 V in both R7520 pads. Typical value is 2.7 V.
4.1.2.1.5.1 Inductors L7512 and L7510 in place and working correctly?
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Disconnect the power supply from the phone and use an ohmmeter to check that L7510 and
L7512 are conducting DC.
4.1.2.1.6 Is TX VCO signal level in the T7503 output high enough?
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WCDMA transmitter has to be active before TX VCO’s output level can be measured. Procedure is
explained in section “Transmitter troubleshooting”.
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Measurements can be done with a spectrum analyser and an RF probe. Spectrum analyser centre
frequency should be set according the used TX channel (see section “Frequency mappings”). RBW
