Synthesizer Troubleshooting - Nokia 3155 Rf Description And Troubleshooting

Nokia Customer Care

Synthesizer Troubleshooting

Faulty synthesizers can cause Rx and Tx failures during tuning, in addition to the VCTCXO
tuning. However, first check for the presence of various LO signals and their proper levels.
If everything fails, it may be necessary to check the reference clock (19.2MHz) which is
needed for the mobile terminal to power up. The 19.2MHz signal is important because
the D2800 processor is sensitive enough to pick up a very weak 19.2MHz clock, resulting
in intermittent problems such as a constant mobile terminal reset.
Following are the synthesizers used in the mobile terminal:
• Dual-band UHF (1009.62MHz for channel 384 in Cell and AMPS bands, and
2088.1MHz for channel 600 in PCS band) with a separate LMX2310 PLL IC
• Rx VHF (256.2MHz for Cell, AMPS, and PCS) with PLL inside the N7100 IC
• Tx UHF (3296.16MHz~3395.88 for Cell and AMPS, 3700~3819.9MHz for PCS)
with PLL inside the N7000 IC
ISSUE 1 07/2005
©2005 Nokia Corporation
3155/3155i (RM-41), 3152 (RM-61)
RF Description and Troubleshooting
Company Confidential Page 45