Nokia Customer Care
Appendix A: RF Troubleshooting
A-92
Company Confidential
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2005 Nokia. All rights reserved
4.1.2.3.3.1.3 VB_EXT voltage ok?
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Measurement can be done with an oscilloscope and a probe.
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Connect the probe to C7518.
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VB_EXT voltage should be 1.325 – 1.375 V. Typical value is 1.35 V.
4.1.2.3.3.1.3.1 R7503 in place and working correctly?
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Check that the component is in place and solder joints are ok
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Disconnect the power supply from the phone and check R7503 resistance value with an ohmmeter
4.1.2.3.3.1.3.2 Capacitors C7518, C7520 and C7570 working correctly?
•
Check that components are in place and solder joints are ok
•
Disconnect the power supply from the phone and use an ohmmeter to check that capacitors are
not short-circuited. If short-circuit is found replace capacitors mentioned above. If this does not
help go to the next step.
4.1.2.3.3.1.3.3 Replace Vinku (N7501) or Hinku (N7500) or both
4.1.2.3.3.1.4 Replace Vinku (N7501)
4.1.2.3.3.2 Is capacitor C7579 in WCDMA PA (N7503) bias line working correctly?
Icont_12 – C7579 short-circuited?
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Check that the capacitor is in place and solder joints are ok
•
Disconnect the power supply from the phone and use an ohmmeter to check that the capacitor is
not short-circuited. If short-circuit is found replace the capacitor.
4.1.2.3.3.3 Replace Vinku (N7501) or WCDMA PA (N7503)
4.1.2.3.4 Replace PA (N7503)
4.1.2.4 Does duplex-filter (Z7502) get correct RF-power from WCDMA PA (N7503)?
•
WCDMA transmitter has to be active before measurements. Procedure is explained in section
“Transmitter troubleshooting”.
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Set TX power level to 0 dBm (Set start level “0” to Phoenix)
•
Measurements can be done with a spectrum analyser and an RF probe. Remember to make correct
frequency setting to the spectrum analyser. Spectrum analyser centre frequency should be set
according the used TX channel (see section “Frequency mappings”)
•
Spectrum analyser RBW = VBW = 10 MHz, Span
≤
2 MHz, sweep time 100 ms
•
Connect the probe to Z7502 TX input. The RF level should be roughly -20…-30 dBm.
