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Appendix A: RF Troubleshooting
4.2.4.4.1 C7560, C7513, C7526 and C2214 ok?
•
Check that components are in place and solder joints are ok
•
Disconnect the power supply from the phone and use an ohmmeter to find out if the VXO-line is
short-circuited to the ground. If short-circuit is found replace C7560, C7513, C7526 and C2214. If
replacing does not help then go to the next steps.
4.2.4.4.2 Replace Retu
4.2.4.4.3 Replace Hinku (N7500) or Vinku (N7501) or VCTCXO (G7501) or all three components
4.2.4.5 VCP1-voltage ok?
WCDMA receiver has to be active before VCP1 voltage can be measured. Procedure is explained in
•
section "Receiver troubleshooting".
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Measurement can be done with an oscilloscope and a probe.
•
Connect the probe to C7507.
•
VCP1 voltage should be about 4.75 V.
4.2.4.5.1 C7507 and C2222 ok?
•
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
C7507 and C2222 are not short-circuited. If short-circuit is found replace faulty capacitor. If this
does not help go to the next steps.
4.2.4.5.2 Retu ok?
4.2.4.5.3 Hinku (N7500) ok?
4.2.4.6 Is there RF power in the RX VCO output at all?
•
WCDMA receiver has to be active before RX VCO's output frequency and output level can be
measured. Procedure is explained in section "Receiver troubleshooting".
•
Measurements can be done with a spectrum analyser and an RF probe. Spectrum analyser centre
frequency should be set according the used RX channel (see section "Frequency mappings". RBW
and VBW = 1 MHz, Span ≤ 200 kHz.
•
Connect the RF probe to the T7501 input.
•
Check if the frequency of the RX VCO is as expected. If the VCO signal is not found try to use wider
span setting. The output level of the VCO should be about -20...-30 dBm.
4.2.4.6.1 RX VCO operating voltage VR1 RX ok?
•
WCDMA receiver has to be active before Hinku's VR1RX voltage can be measured. Procedure
is explained in section "Receiver troubleshooting"
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