Nokia 6255 Rf Description And Troubleshooting

Also see for 6255: User guide User guide User guide User guide Disassembly manual

Contents

Nokia 6255 Rf Description And Troubleshooting Manual pdf 54 page image

6255/6255i/6256/6256i (RM-19)RF Description and Troubleshooting Nokia Customer CarePage 54 ©2005 Nokia Corporation Company Confidential Issue 2 05/2005VCTCXO Manual TuningThe VCTCXO can be manually tuned to verify when a mobile terminal is tuned incorrectlyor if mobile terminal cannot make a call. Monitor the RF signal at the mobile terminal’soutput.1. On the Phone Control dialog box, click the LOCAL button in the Phone Statearea to put the mobile terminal into Local Mode. (See Figure 9 on page 16 for anexample of the Phone Control dialog box.)2. Click the Execute button.3. On the AMPS Control dialog box, set the Set Channel field to 384, the PowerLevel field to 5, and select the Transmitter ON check box. (See Figure 10 onpage 16 for an example of the AMPS Control dialog box.)4. Click the Rx RFI tab, make sure the AFC Control check box is cleared, and clickExecute.5. The frequency accuracy of the VCTCXO can be measured using an HP8960 callboxin AMPS mode or a spectrum analyzer at the output of the transmit chain.• If using a spectrum analyzer, set the center frequency to 836.52MHz and thespan to 2MHz initially. Establish a marker at 836.52Mhz.• If using an HP8960, set the callbox System Type to AMPS, and set the ACCchannel to 384. Use the Frequency Stability measurement to center theVCTCXO (minimum Frequency Error).6. Use the RF PDM component to adjust the AFC to center the VCTCXO. The tuningrange is approximately +/-10kHz.7. Adjust the AFC so that the output signal is within +/-150MHz. If using aspectrum analyzer, narrow the span to 1kHz or less.8. Replace the UEM if the VCTCXO does not tune correctly.7 If you do not see the VCTCXO signal attest points 1-5, check the voltage at VR32.8V8 AFC voltage 1 to 3 Volts (adjustable with the AFC slideron the RF PDM Control in Phoenix)1.2V for PDM 00V for PDM -10242.4V for PDM 1024N/A If an AFC voltage is missing, check theUEM.Table 15: VCTCXO Test Point Output Values (Continued)TestPoint Description Value