Appendix A: RF Troubleshooting
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A-79
ohmmeter.
•
If resistance of R7520 is correct then replace L7511.
4.1.1.3 Is WCDMA PA (N7503) transmitting RF-power at all?
•
WCDMA transmitter has to be active before measurements. Procedure is explained in section
“Transmitter troubleshooting”.
•
Set TX power level to 0 dBm (Set start level “0” to Phoenix)
•
Measurements can be done with a spectrum analyser and an RF probe. Remember to make correct
frequency setting to the spectrum analyser. Spectrum analyser centre frequency should be set
according the used TX channel (see section “Frequency mappings”).
•
Spectrum analyser RBW = VBW = 10 MHz, Span
≤
2 MHz, sweep time 100 ms
•
Connect the probe to Z7505 input. The RF level should be roughly -16…-28 dBm.
4.1.1.3.1 Does WCDMA PA (N7503) get operating voltage Vcc12?
•
WCDMA transmitter has to be active before measurements. Procedure is explained in section
“Transmitter troubleshooting”.
•
Measurement can be done with an oscilloscope and a probe.
•
Connect the probe to R7525
•
Vcc12 voltage level should be 3.05 – 5.4 V. Typical value is 4.0 V.
4.1.1.3.1.1 R7525 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 R7525 resistance value with an ohmmeter
4.1.1.3.1.2 PA operating voltage VBAT_PA ok?
•
WCDMA transmitter has to be active before measurements. Procedure is explained in section
“Transmitter troubleshooting”.
•
Measurement can be done with an oscilloscope and a probe.
•
Connect the probe to C7569 (or C7564, C7583)
•
Voltage level should be 3.05 – 5.4 V. Typical value is 4.0 V.
4.1.1.3.1.2.1 Ferrite Z7500 ok?
•
Check that component is in place and solder joints are ok
•
Disconnect the power supply from the phone and use an ohmmeter to check that inductor is
conducting DC.
