Does Wcdma Pa (N7503) Get Correct Bias Currents Icont11 And Icont12 - Nokia RM-42 Service Manual

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• Disconnect the power supply from the phone and check resistors resistance values with an
ohmmeter
• Use an ohmmeter also to check that L7514 is conducting DC.
4.3.1.5 Replace SMPS N7504

4.3.2 Does WCDMA PA (N7503) get correct bias currents Icont11 and Icont12?

WCDMA transmitter has to be active before measurements. Procedure is explained in section
•
"Transmitter troubleshooting".
• Set TX power level to -40 dBm (Set start level to "-40.0" in phoenix)
• Measurements can be done with an oscilloscope and a probe.
Connect the probe to C7579
-
WCDMA PA bias current Icont_12 should look as a constant 2.5 - 2.6 V DC-voltage with all power
-
levels.
Connect the probe to C7576 pad. Notice: C7576 is a non-assembled component so the probe
-
should be connected to the pad that can be still found from the PWB.
WCDMA PA bias current Icont_11 should look as a constant 2.5 - 2.6 V DC-voltage with all power
•
levels.
4.3.2.1 Vinku (N7501) RB_EXT voltage ok?
• WCDMA transmitter has to be active before Vinku's RB_EXT voltage can be measured. Procedure is
explained in section "Transmitter troubleshooting".
Measurement can be done with an oscilloscope and a probe.
•
• Connect the probe to R7521.
• RB_EXT voltage should be 1.325 – 1.375 V.
4.3.2.1.1 VREFRF01-voltage ok?
• Measurement can be done with an oscilloscope and a probe.
• Connect the probe to R7503.
• VREFRF01 voltage should be 1.325 – 1.375 V. Typical value is 1.35 V.
4.3.2.1.1.1 Desolder R7503. Is VREFRF01 voltage still wrong?
• Remember to solder a new component to R7503 pads after measurement.
4.3.2.1.1.1.1 Capacitors C7518, C7520 and C7570 working correctly?
• Check that components are in place and solder joints are ok
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Appendix A: RF Troubleshooting