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Introduction to RF troubleshooting

For service

There are no changeable RF components on the PWB when servicing the phone. In case of RF failure, the entire

PWB must be replaced.

Go to RF troubleshooting for service (Page 7–5) for assistance.

Note: Most components are under shielding, and must not be replaced for service.

For analysis

On the following pages you will find a step-by-step troubleshooting procedure and reference measurements

at the relevant signal points. For functional descriptions, please refer to the System module section (Page 8–5).

Note: Most test points are not accessible unless shielding cans are cut open. This must ONLY be done

by the Return analysis technicians and for analysis only!

Notes on reference measurements

• LF & DC signals are measured with Textronix 100 MHz Scope (TDS3014) and P3010 13 pF probe.

• RF signals are measured with R&S FSIQ 7 GHz Spectrum Analyzer and Agilent resistive divider probe (10 dB,

500Ω).

• Please be aware that the RF connector on service adaptor is leaking power (into air) and acts as noise source

when probing on RX chain. In 1800 band the problem is most severe while there is no external LNA to amplify

the signal above the noise level like in the 1900 band. In 900 band the leakage is not as high due to lower

frequency.

• GSM SA settings: RBW=500 kHz, VBW=500 kHz.

• Bluetooth SA settings: RBW=2 MHz, VBW=2 MHz.

• All reference measurements were made on a RM-13 phone (GSM900).

• RF loss Module Repair Jig: 900: 0.3 dB, 1800: 0.6 dB and 1900: 0.6 dB. Bluetooth is 1.8 dB.

Note: At the time of publishing this manual, not all information and all values were available for

GSM850. This will be added in the next issue.

RF troubleshooting for service

No RF related components will be changed in service. If the RF module does not function properly, the entire

PWB will be replaced. This is how you find out if RF is OK:

1 Place the PWB in the module jig

2 Run the Phoenix auto tuning.

If “fail”, replace PWB.

If “pass”, continue to the next step.

3 Use a test SIM card and set the module to normal mode.

4 Check basic parameters in call mode (all bands) and make a BER measurement.

If “fail”, replace PWB.

If “pass”, continue to the next step.

5 Place the PWB in the phone again and reassemble the phone.

6 Use a test SIM card, set to normal mode and use a GSM tester with antenna or RF coupler.

Measure basic RF parameters in call mode.

If “fail”, replace antenna assy.

RM-13/33

RF Troubleshooting and Tuning Nokia Customer Care

9240218 (Issue 1) Company Confidential Page 7–5