User Guide

Nokia Customer Care

Appendix A: RF Troubleshooting

A-110

Company Confidential

• Disconnect the power supply from the phone and check resistors resistance values with an

ohmmeter

• 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?

• WCDMA transmitter has to be active before measurements. Procedure is explained in section

“Transmitter troubleshooting”.

• Set TX power level to -40 dBm (Set start level to “-40.0” in phoenix)

• Measurements can be done with an oscilloscope and a probe.

- Connect the probe to C7579

- WCDMA PA bias current Icont_12 should look as a constant 2.5 - 2.6 V DC-voltage with all power

levels.

- 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.

• 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?

• WCDMA transmitter has to be active before Vinku’s RB_EXT voltage can be measured. Procedure is

explained in section “Transmitter troubleshooting”.

• Measurement can be done with an oscilloscope and a probe.

• Connect the probe to R7521.

• RB_EXT voltage should be 1.325 – 1.375 V.

4.3.2.1.1 VREFRF01-voltage ok?

• Measurement can be done with an oscilloscope and a probe.

• Connect the probe to R7503.

• 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?

• 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?

• Check that components are in place and solder joints are ok