Nokia RM-42 Service Manual
Also see for RM-42: Service manual
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Nokia Customer Care Appendix A: RF TroubleshootingA-40Company ConfidentialCopyright © 2005 Nokia. All rights reserved3.1.2.1.7.2 Replace balun T75033.1.2.1.8 Replace Vinku (N7501) or GSM PA (N7502)• If the output level of Vinku is higher than wanted then replace GSM PA (N7502). Otherwise replaceTX ASIC Vinku (N7501).3.1.2.2 Does GSM PA (N7502) have enough RF-power in its input?• 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 andsweep time at least 2.5 seconds.• EGSM900: Connect the probe to J7521 (test point). The RF level should be roughly -15…-20 dBm.• GSM1800 or GSM1900: Connect the probe to R7512 output. The RF level should be roughly -20…-30 dBm.3.1.2.2.1 EGSM900: Replace SAW Z75043.1.2.2.2 GSM1800/GSM1900: Is Vinku (N7501) output RF-signal coming correctly to the T7502 (Balun)?• GSM transmitter has to be active before measurements Procedure is explained in section“Transmitter troubleshooting”.• Set TX power level to the maximum (“0” in GSM1800/GSM1900)• 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”).• 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 andsweep time at least 2.5 seconds.• GSM1800 or GSM1900: Connect the probe to T7502 input. There are two input ports in T7502because the input port is balanced. The RF level should be roughly -25 dBm in both inputs.3.1.2.2.2.1 Matching components ok?GSM1800/GSM1900: C7575 and C7577 |
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