Nokia RM-42 Service Manual

Also see for RM-42: Service manual

Contents

Appendix A: RF Troubleshooting Nokia Customer CareCompany ConfidentialCopyright © 2005 Nokia. All rights reservedA-77• Measurement can be done with an oscilloscope and a probe.• Connect the probe to R7520• DC voltage level should be 2.65 – 2.86 V in both R7520 pads. Typical value is 2.7 V.4.1.1.1.10.1 Inductors L7512 and L7510 in place and working correctly?• Disconnect the power supply from the phone and use an ohmmeter to check that L7510 andL7512 are conducting DC.4.1.1.1.11 VCTCXO frequency and output level ok?• 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)".4.1.1.1.11.1 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 V4.1.1.1.11.1.1 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.4.1.1.1.11.1.2 Replace Retu4.1.1.1.11.1.3 Replace Hinku (N7500) or Vinku (N7501) or VCTCXO (G7501) or all three components4.1.1.1.11.2 BB AFC-voltage ok?• Measurement can be done with an oscilloscope and a probe• Connect the probe to R7509 (or C7533)• AFC-voltage may vary between 0.1 - 2.3 V. Typical value is 1.2 V. Phoenix “RF Controls” tool can beused to change the AFC value. Voltage level should be about 0.1 V with AFC value -1024 and about2.3 V with AFC value 1023.4.1.1.1.11.2.1 Low pass filter components R7509 and C7533 ok?• Check that components are in place and solder joints are ok