Does The Phone Give Realistic Rssi-Values; Is Hinku (N7500) Asic Receiving Rf-Power Correctly From The Gsm-Antenna Connector - Nokia 6680 RM-36 Service Manual

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found replace C7533. If this does not help then go to the next steps.
3.1.3.3.2.2 VCTCXO ok?
• Remove R7509. If AFC-voltage is correct after removing then replace faulty VCTCXO G7501 and
solder R7509 (new component) back to the PWB
3.1.3.3.2.3 Replace Retu
3.1.3.3.3 Replace VCTCXO G7501

3.2 Does the phone give realistic RSSI-values?

Attach the phone to the product specific test jig and a signal generator to the RF-coupler. Coupler
attenuation should be also taken into account during measurements.
Use the signal generator to supply -90 dBm RF-level (unmodulated signal) to the phone via the
antenna coupler. Set generator RF-level to -90 dBm + cable and coupler attenuation. This
measurement should be performed in a RF-shielded environment because existing GSM-network base
stations can disturb this measurement otherwise.
• Set RF-generator frequency as following:
EGSM900: 942.46771 MHz (channel 37)
-
GSM1800: 1842.86771 MHz (channel 700)
-
GSM1900: 1960.06771 MHz (channel 661)
-
• Use Phoenix testing & tuning software to perform GSM receiver activation and RSSI measurement
for proper channels. Procedure is explained in section "GSM RX chain activation for manual
measurements" (Start "Testing" -> "GSM" -> "RSSI Reading" tool in Phoenix. Select the correct
band and channel).
• "RSSI Reading" -tool should show quite exact -90 dBm RSSI level. Remember to take into account
attenuation between the phone and signal generator. Test also Q and I branches separately.
Signal level in both I and Q lines should be about -93 dBm
Increase signal generator RF level to -60 dBm. Phoenix "RSSI Reading" tool should show now quite
•
exact RSSI level -60 dBm. Test also Q and I branches separately. Signal level in both I and Q lines
should be about -63 dBm
• If RSSI-levels are not as expected separate the phone into parts and place to the module jig.
Connect the signal generator to the module jig GSM RF connector (Notice that there are three
antenna connectors in the module jig, one for GSM, one for WCDMA and one for Bluetooth. Make sure
that all connections are made to the correct RF-connector).

3.2.1 Is Hinku (N7500) ASIC receiving RF-power correctly from the GSM-antenna connector?

GSM receiver has to be active before measurements. Procedure is explained in section "GSM RX
•
chain activation for manual measurements."
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Appendix A: RF Troubleshooting