Appendix A: RF Troubleshooting
Nokia Customer Care
Company Confidential
Copyright
©
2005 Nokia. All rights reserved
A-34
SAW-filter Z7504 or balun T7502 can be also faulty/badly soldered and causing short-circuit,
but probability to this is quite low. For example: VINKU is transmitting too low power in
GSM850/EGSM900-band but TX-power is ok in other GSM-bands. Then it’s almost clear that
VINKU (N7501) is faulty or badly soldered and the component should be replaced.
3.1.2.1.1 RF operating voltage VBAT_ASIC ok?
•
See section
“RF operating voltage VBAT_ASIC ok?”
3.1.2.1.2 Are Vinku (N7501) regulator voltages VREG1, VREG2 ok?
•
GSM transmitter has to be active before VREG1 and VREG2 voltages can be measured.
Procedure is explained in section “Transmitter troubleshooting”.
•
Measurements can be done with an oscilloscope and a probe.
•
VREG1: Connect the probe to C7543
•
VREG2: Connect the probe to C7548 (or C7547)
•
VREG1 and VREG2 voltage levels should be 2.65 – 2.86 V. Typical value is 2.7 V.
3.1.2.1.2.1 Vinku (N7501) RB_EXT voltage ok?
•
GSM 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.
3.1.2.1.2.1.1 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.
3.1.2.1.2.1.1.1 Desolder R7503. Is VREFRF01 voltage still wrong?
•
Remember to solder a new component to R7503 pads after the measurement.
3.1.2.1.2.1.1.1.1 Capacitors C7518, C7520 and C7570 working correctly?
•
Check that components are in place and solder joints are ok
•
Disconnect the power supply from the phone and use an ohmmeter to check that capacitors
are not short-circuited. If short-circuit is found replace capacitors mentioned above. If this
does not help go to the next step.
Summary of Contents for RM-57
Page 391: ...www s manuals com ...
