Transmitter Troubleshooting Guidelines; Transmitter Troubleshooting Setup - Nokia 6275 Rf Description And Troubleshooting

Nokia Customer Care

Transmitter Troubleshooting Guidelines

Use the following guidelines when troubleshooting.
• Always perform visual inspection of PCB under microscope to check proper
placement, rotation, and soldering of components.
• Look for the presence of a well-defined CDMA modulated signal on a spectrum
analyzer at the correct frequency. If a signal is present but off frequency or the
shape looks distorted, check the synthesizer. Possibly, one of the synthesizers is
not locked or the VCO has no output signal. Check the synthesizers for proper
frequency and amplitude. See
Troubleshooting" on page 33.
• Check that power supplies to the transmitter have the correct voltage. See
Component
• If the signal is very low in amplitude, check the probing diagram to determine
what part of the TX chain is 'broken'. See
• Check that AGC PDMs produce and adjust TX power within the proper limits.

Transmitter Troubleshooting Setup

Use the following sets of procedures to troubleshoot the transmitter using Phoenix.
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 be
necessary to break one to determine the cause.
Use the following sections to set up troubleshooting in Phoenix according to the band
you are using:
• "AMPS Tx
• "Cell Tx
• "PCS Setup" on page
Issue 1 - September 2006
"Tx Output
Diagram" on page 19.
Setup" on page 12
Setup" on page 13
15
Company Confidential
6275/6275i (RM-154)
RF Description and Troubleshooting
Spectrum" on page 18
"DC Test Points" on page 20.
and "Synthesizer
"Tx RF
Page 11