Tdma1900 Uhf Synthesizers; Ghz Uhf Synth Troubleshooting - Nokia NSW-5 Series Service Manual

NSW-5
Disassembly and Troubleshooting Instructions

TDMA1900 UHF Synthesizers

2 Ghz UHF synthesizer generates desired injection frequencies for TX
and RX chain. The output frequency of the VCO depends on the control
voltage of the PLL–circuit

2 GHz UHF Synth Troubleshooting

Is the fequency
locked ?
What is VCO output
level ?, G860
P:>–10 dBm
Check local input
level of frontend
(N721, pin 1)
P:>–10 dBm
Check feedback
input level of
N880
P=–10–0 dBm
Check N880
pin 11 (SCLK):2.8V
pin 12 (SDATA):2.8V
pin 13 (SENA2):2.8V
SENA is 0 during SCLK
and SDATA
Page 50
N
N
Change G860
Y
Check R863
N
N
Y
N
Check C891
Start BB
troubleshooting
N
E Nokia Mobile Phones Ltd.
PAMS Technical Documentation
Note!
The Oscillator is locked, when the
frequency and Vcnt are stable.
Frequency=2046.27 ..2106.15MHz
Vcnt=1 .4V,C861
Note!
Check all solderings, missing components
and supply voltage
NOTE!
Check N880 supply voltages
Issue 1 10/00