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 10 page image

6235/6235i/6236i (RM-60)RF Description and TroubleshootingPage 10 ©2005 Nokia Corporation Company Confidential Issue 1 04/2005Transmitter Troubleshooting GuidelinesUse some of the following guidelines when as you are troubleshooting.• Always perform visual inspection of PCB under microscope to check properplacement, rotation, and soldering of components.• Look for presence of well-defined CDMA modulated signal on spectrum analyzerat correct frequency. If signal is present but off frequency or shape looksdistorted, check synthesizer. Possibly, one of the synthesizers is not locked, orVCO has no output signal. Check the synthesizers for proper frequency andamplitude. See "Transmitter Output Spectrum" on page 20 and "SynthesizerTroubleshooting" on page 43.• Check that power supplies to transmitter have correct voltage See "Tx DC TestPoints" on page 22.• If signal is very low in amplitude, check probing diagram to determine what partof TX chain is ‘broken’. See "Tx RF Test Points" on page 23.• Check that AGC PDMs produce and adjust TX power within the proper limits.See Figure 9 on page 13, Figure 12 on page 16, and Figure 13 on page 18.Transmitter Troubleshooting SetupUse the following sets of procedures to troubleshoot the transmitter using Phoenix. Dueto the compact layout of the mobile terminal, some of the major test points are notaccessible without destroying the shield frames and the EL lamp. For example, duplexers/diplexer/couplers test points are blocked by the test jig, the PA test points areunderneath the shield frame, and the BBIQ points are underneath the EL lamp.To minimize effort, check the following in order:1. Tx power at the RF connector.2. All Tx DC points.3. All soldering jig points for the whole Tx chain.4. UHF LO presence:• If the UHF LO is present, check the N7000 output.• If the UHF LO is not present, it is a synthesizer problem.5. If there is no N7000 output:a. Change the N7000.b. If the problem persists, reflow the duplexers, diplexer, and couplers.c. If the problem persists, change the PA.6. If there are several failed mobile terminals with the same symptoms, it may benecessary to break one to determine the cause.Use the following sections to set up troubleshooting in Phoenix according to the band