Nokia 6680 RM-36 Service Manual page 320

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• Check that the component is in place and solder joints are ok
• Disconnect the power supply from the phone and check R7503 resistance value with an ohmmeter
4.1.1.1.3.1.3.2 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.
4.1.1.1.3.1.3.3 Replace Vinku (N7501) or Hinku (N7500) or both
4.1.1.1.3.1.4 Replace Vinku (N7501)
4.1.1.1.3.2 Are capacitors in Vinku (N7501) regulator lines working correctly?
VREG1: C7543
VREG2: C7547, C7548, C7554, C7555, C7553, C7552, C7558 and C7567
• 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 regulator lines
are not short-circuited to the ground. If short-circuit is found replace capacitors mentioned above.
If this does not help go to the next step.
4.1.1.1.3.3 TX VCO (G7502) ok?
4.1.1.1.3.4 Replace Vinku (N7501)
4.1.1.1.4 VXO-voltage ok? (=Vdig).
• Measurement can be done with an oscilloscope and a probe
• Connect the probe to C7560 (or C7526, C7513)
• VXO-voltage should be about 2.5 V
4.1.1.1.4.1 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.
4.1.1.1.4.2 Replace Retu
4.1.1.1.4.3 Replace Hinku (N7500) or Vinku (N7501) or VCTCXO (G7501) or all three components
4.1.1.1.5 VCP2-voltage ok?
A-74
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Appendix A: RF Troubleshooting