Amps & Tdma Uhf Synthesizer; 1Ghz Uhfsynthesizer Troubleshooting - Nokia NSC/W–1/3 Series Disassembly & Troubleshooting Instructions

NSC/W–1/3
Disassembly & Troubleshooting Instructions
AMPS & TDMA UHF SYNTHESIZER
The 1GHz UHF VCO (G820) generates the first injection for RX
(869...897MHz) and the final injection for TX (824...849 MHz) . The output
frequency of the module depends on thje DC control voltage supplied by the
PLUSSA.

1GHz UHFsynthesizer troubleshooting

Is Frequency
locked ?
What is VCO output
level ? G820
P:~0 dBm
Check local input
level of frontend
(N701, pin 1)
P:~0 dBm
Check feedback
input level of
PLUSSA
(N750, pin 21)
P:~10 dBm
Check PLUSSA (N750)
pin 54 (SCLK):2.8V
pin 55 (SDATA):2.8V
pin 56 (SENA1):2.8V
SENA is 0 during SCLK
and SDATA
Page 38
N
N
Change G820
Y
N
Check R821
N
Y
N
Check C821
Y
N Start BB
troubleshooting
Technical Documentation
Note!
The oscillator is locked when the frequency
and Vcnt are stable.
Frequency = 985.23...1010.2
Vcnt = 1.2...3.6 V
(C831)
Note!
Check all soldering & missing components
and supply voltage
Note !
Check PLUSSA supply voltages
Original 11/99
PAMS