PAMS
Technical Documentation
NSC/W–1/3
Disassembly & Troubleshooting Instructions
Page 39
Original 11/99
TDMA1900 UHF Synthesizer 2 GHz (ONLY DUALBANDER)
The 2GHz UHF synthesizer generates the needed injection frequencies for
TX and RX chain. The output frequency of the VCO depends on the control
voltage supplied by the PLL circuit.
2 GHz UHF synthesizer troubleshooting
Is Frequency
locked ?
N
What is VCO output
level? G860
P:~0 dBm
Check local input
level of frontend
(N721, pin 1)
P:~0 dBm
Change G860
Check R867
Check feedback
input level of
N880, pin 6)
P:~–10 dBm
Check R886
Note!
Frequency = 985.23...1010.2
Vcnt = 1.2...3.6 V , C861
Note!
Check all soldering & missing components
N
Y
N
Y
N
N
Check N880
pin 11 (SCLK):2.8V
pin 12 (SDATA):2.8V
pin 13 (SENA2):2.8V
SENA is 0 during SCLK
and SDATA
and supply voltage.
Start BB
troubleshooting
Note!
Check N880
supply voltages
N
Y