Tdma 1900 Rx - Nokia NSW-5 Series Service Manual

PAMS Technical Documentation

TDMA 1900 RX

Apply 1960.02 MHz
(Ch 1000)–70 dBm
signal (no modulation)
to external antenna
connector (X991)
Check level of
IF2–sinal ( 4 50 kHz)
in RF/BB–interface
from resistor R798
P: ≅ –13 dBm
N
Check UHF VCO
control voltage from
capasitor C861
V: 1.0 4.0 V
Y
Check 3 multiplier output
level (58.32 MHz )
from capasitor C745
P: ≅ –10 –20 dBm
Y
Check level
(1960.02 MHz )
from duplex filter
(Z960) input
P: ≅ –70 dBm
Y
Check level
from frontend (N721)
LNA input pin no.7
P: ≅ –70 dBm
Y
Check level
from LNA output
(N721) pin no.10
P: ≅ –56 dBm
Y
Check level from MXR
input (N721) pin no.12
P: ≅ 0–2 dB less than at LNA
output pin no. 10
Y
Issue 1 10/00
Disassembly and Troubleshooting Instructions
NOTE! If RX800 check is OK, then RX1900
Note!
troubleshooting should be concentrated only on
Signal level
duplexer Z960 and frontend N721 area and
surrounding components.
Y TDMA 1900
RX–chain is OK.
Start baseband troubleshooting
(signal go next to COBBA IC N250)
N
Start synthesizer
troubleshooting
N
Start synthesizer
troubleshooting
N
Change diplexer Z970
N
Change duplex filter Z960
or coil L721
N
Change frontend N721
N
N
Change RX bandfilter Z726
E Nokia Mobile Phones Ltd.
Note!
Check all soldering and
components in antenna
circuit before changing
Note!
Check all soldering and
discrete components of
frontend.
Note!
AGC2 is on
= gain is in high state
(~ 2.8 V at N721 pin no.9)
Note!
Check all soldering
NSW-5
Page 35