Nokia RM-42 Service Manual
Also see for RM-42: Service manual
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          | |
Nokia Customer Care Appendix A: RF TroubleshootingA-96Company ConfidentialCopyright © 2005 Nokia. All rights reservedis not as expected then replace T7503. VCO shield has to be removed before measurement.Remember to solder the shield back after the phone repairing.4.1.3.1.2.4 Are components near the TX VCO ok?C7571, R7519, R7523, C7573 and C7568 working correctly?• Check that components are in place and solder joints are ok• Disconnect the power supply from the phone and check resistors resistance values with anohmmeter.• Use an ohmmeter to check also that capacitors are not short-circuited4.1.3.1.2.5 Replace Vinku (N7501) or TX VCO (G7502) or both4.1.3.1.3 Replace TX VCO G75024.1.3.2 Is TX VCO signal level in the T7503 output high enough?• WCDMA transmitter has to be active before TX VCO’s output level can be measured. Procedure isexplained in section “Transmitter troubleshooting”.• Measurements can be done with a spectrum analyser and an RF probe. Spectrum analyser centrefrequency should be set according the used TX channel (see section “Frequency mappings”). RBWand VBW = 1 MHz, Span ≤ 200 kHz.• Check the level of the VCO frequency in T7503 outputs. The level should be about -30…-35 dBm inboth output lines. If the signal level is correct in the input (about -25 dBm) but output level is notas expected then replace T7503. VCO shield has to be removed before measurement. Remember tosolder the shield back after the phone repairing.4.1.3.2.1 TX VCO G7502 output level high enough?• WCDMA transmitter has to be active before TX VCO’s output frequency and output level can bemeasured. Procedure is explained in section “Transmitter troubleshooting”.• Measurements can be done with a spectrum analyser and an RF probe. Spectrum analyser centrefrequency should be set according the used TX channel (see section “Frequency mappings”). RBWand VBW = 1 MHz, Span ≤ 200 kHz.• Connect the RF probe to the T7503 input. VCO shield has to be removed before measurement.Remember to solder the shield back after the phone repairing.• Check if the frequency of the TX VCO is as expected. If the VCO signal is not found try to use widerspan setting. The output level of the VCO should be about -25 dBm.4.1.3.2.1.1 Replace TX VCO G75024.1.3.2.2 Replace balun T7503 |
Related manuals for Nokia RM-42
This manual is suitable for:
manualsdatabase
Your AI-powered manual search engine