Nokia RM-42 Service Manual
Also see for RM-42: Service manual
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Appendix A: RF Troubleshooting Nokia Customer CareCompany ConfidentialCopyright © 2005 Nokia. All rights reservedA-313.1.1.1.9.3 Retu ok?3.1.1.1.10 VCTCXO frequency and output level correct?• Measurement can be done with an oscilloscope and a probe.• Connect the probe to C7529 (or C7582)• The frequency of the VCTCXO should be quite exactly 38.4 MHz and level about 0.5 - 0.9 Vpp.Example of the correct VCTCXO output signal is presented in figure 6.5.1. "VCTCXO Output (DC Offset1.24 V)"..3.1.1.1.10.1 VXO-voltage ok? (=Vdig).• Measurement can be done with an oscilloscope and a probe• Connect the probe to C7560 (or C7526, C7513)• VXO-voltage should be about 2.5 V3.1.1.1.10.1.1 C7560, C7513, C7526 and C2214 ok?• Check that components are in place and solder joints are ok• Disconnect the power supply from the phone and use an ohmmeter to find out if the VXO-line isshort-circuited to the ground. If short-circuit is found replace C7560, C7513, C7526 and C2214. Ifreplacing does not help then go to the next steps.3.1.1.1.10.1.2 Replace Retu3.1.1.1.10.1.3 Replace Hinku (N7500) or Vinku (N7501) or VCTCXO (G7501) or all three components3.1.1.1.10.2 BB AFC-voltage ok?• See section "BB AFC-voltage ok?"3.1.1.1.10.3 Replace VCTCXO G75013.1.1.1.11 Replace Vinku (N7501)3.1.1.2 Is there RF-power in the GSM PA (N7502) input at all?• GSM transmitter has to be active before measurements. Procedure is explained in section“Transmitter troubleshooting”.• Set TX power level to the maximum (“5” in EGSM900 and “0” in GSM1800/GSM1900)• Measurements can be done with a spectrum analyser and an RF probe. Remember to make correctfrequency settings to the spectrum analyser. Spectrum analyser centre frequency should be setaccording the used TX channel (see section “Frequency mappings”).• Spectrum analyser RBW and VBW = 1 MHz, Span = 0, sweep time 1 ms. Notice that GSMtransmission has pulsed nature and power should be measured during TX burst (triggeringneeded). Another possibility is to use following settings: RBW = VBW = 1 MHz, Span 200 kHz and |
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