Nokia RM-42 Service Manual

Also see for RM-42: Service manual

Contents

Nokia Customer Care Appendix A: RF TroubleshootingA-38Company ConfidentialCopyright © 2005 Nokia. All rights reserved• GSM transmitter has to be active before TX control voltage TXC can be measured. Procedure isexplained in section “Transmitter troubleshooting”.• Set TX power level first to the maximum (“5” in EGSM900 and “0” in GSM1800/GSM1900)• Measurement can be done with an oscilloscope and a probe.• Connect the probe to C7549• Typical TX control voltage TXC timing should look somehow similar to figure 6.5.2 “TXC in GSMmode (DC offset 0 V)” (EGSM900 TX power level 5) and voltage levels should be roughly:- EGSM900: 1.8 V while TX burst and 0 V otherwise.- GSM1800/GSM1900: 1.8 V while TX burst and 0 V otherwise.• Change the TX to the minimum power level (“19” in EGSM and “15” in GSM1800/GSM1900)• Typical TX control voltage TXC levels should be now about:- EGSM900: 1.0 V while TX burst and 0 V otherwise.• GSM1800/GSM1900: 0.7 V while TX burst and 0 V otherwise.3.1.2.1.4.1 R7514 in place and working correctly?• Check that the component is in place and solder joints are ok• Disconnect the power supply from the phone and check R514 resistance value with an ohmmeter3.1.2.1.4.2 C7549 working correctly?• Check that the component is in place and solder joints are ok• Disconnect the power supply from the phone and check with an ohmmeter that C7549 is notshort-circuited.3.1.2.1.4.3 Retu ok?3.1.2.1.5 Does GSM PA (N7502) get correct DET_SW_G -voltage from Vinku ASIC (N7501)?• GSM transmitter has to be active before DET_SW_G voltage can be measured. Procedure isexplained in section “Transmitter troubleshooting”.• Measurement can be done with an oscilloscope and a probe.• Connect the probe to C7595 pad. Notice: C7595 is a non-assembled component so the probeshould be connected to the pad that can be still found from the PWB.• DET_SW_G voltage should be about 2.8 V while TX burst and 0 V otherwise.3.1.2.1.5.1 C7595 working correctly?