User Guide

NSW-4

Disassembly & Troubleshooting

PAMS Technical Documentation

Page 45

Issue 1 Final Draft

08/00

 Nokia Mobile Phones Ltd.

TDMA1900 UHF SYNTHESIZER

2GHz 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.

Is the fequency

locked ?

What is VCO output

levet ?, G881

P=–10–0 dBm

Check local input

level of frontend

(N721, pin 1)

P=–10–0 dBm

Change G881

Check C889 &

C882

Check feedback

input level of

N870

P=–10–0 dBm

Note!

Frequency = 985.23...1010.2

Vcnt = 1.3...3.5 V , C887

Note!

Check all soldering & missing components

Check N870

pin 11 (SCLK):2.8V

pin 12 (SDATA):2.8V

pin 13 (SENA1):2.8V

SENA is 0 during SCLK

and SDATA

Check C888 &

L880

Start BB

troubleshooting