Nokia 6235 Troubleshooting Manual

Also see for 6235: User guide User guide User guide Disassembly/Assembly Antenna Description and Troubleshooting

Contents

Nokia 6235 Troubleshooting Manual Manual pdf 43 page image

Nokia Customer Care RF Description and Troubleshooting6235/6235i/6236i (RM-60)Issue 1 04/2005 ©2005 Nokia Corporation Company Confidential Page 43IMPORTANT: You must check for both conditions before replacing the chip. If youhave no LO signal, refer to "UHF Synthesizer Troubleshooting" on page 52. If you have asignificant supply voltage drop on one of the supply pins, then replace the N7160.Synthesizer TroubleshootingFaulty synthesizers can cause both Rx and Tx failures during tuning, in addition to theVCTCXO tuning. However, first check for the presence of various LO signals and theirproper 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 isalso important because the D2800 processor is sensitive enough to pick up a very weak19.2MHz clock, resulting in intermittent problems such as a constant mobile terminalreset.Following are the synthesizers used in the mobile terminal:• Dual-band UHF (1009.62MHz for channel 384 in Cell and AMPS bands, and2088.1MHz 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 ICTable 6: N7160 Conditions and Supply CurrentsCondition: Local Mode, SetRx Only in RF Main ModeSupply Current(From Power Supply)Good mobile terminal 100mANo UHF LO signal present 254mAPin 13 shorted 255mA