User Guide

NSW-4

Disassembly & Troubleshooting

PAMS Technical Documentation

Page 44

Issue 1 Final

Draft 08/00

 Nokia Mobile Phones Ltd.

AMPS& TDMA800 UHF SYNTHESIZER

1 GHz UHF VCO (G880) generates the first injection for RX (869...897) and the final

injection for TX (824...849 MHz). The output frequency of the module depends on the

DC–control voltage supplied by EROTUS in line PD2.

Is the frequency

locked?

What is VCO output

levet ?, G800

P=–10–0 dBm

Check local input

level of frontend

(N701, pin 1)

P=–10–0 dBm

Change G880

Check C827 &

L820

Check feedback

input level of

EROTUS

(at C825)

P=–10–0 dBm

Change C825

Note!

Frequency = 985.23...1010.2

Vcnt = 1.3...3.5 V , C826

Note!

Check all soldering & missing components

Check EROTUS (N700)

(SCLK):2.8V

pin 55 (SDATA):2.8V

(SENA1):2.8V

SENA is 0 during SCLK

and SDATA

Start BB

troubleshooting