CCS Technical Documentation
RF Troubleshooting
Company Confidential
NEM-4
Issue 1 09/2003
Copyright
2003 Nokia Corporation.
Page 6(b)-85
Company Confidential
goes through the directional coupler (one of the power control loop components) to the
Antenna Switch.
Antenna Switch
The Antenna Switch works as a diplexer between RX and TX Bands. Moreover, it partly
suppresses the harmonics generated by the PA. Mjoelner RF ASIC controls the antenna
switch by three voltages CONT1, CONT2 and CONT3. The following table shows the dif-
ferent states.
Fault finding chart for GSM1800/GSM1900 transmitter
If the Tx output is too high, then it is most likely that there is a problem within the Power
Control loop.
Mjoelner is receiving the Reference TXC from Baseband and not getting any feedback
CONT1
[Volt]
CONT2
[Volt]
CONT3
[Volt]
EGSM Rx
DCS Rx
PCS Rx
EGSM Tx
DCS/PCS
Tx
0
0
0
X
0
0
0
X
0
0
2.7
X
0
2.7
0
X
2.7
0
0
X
START
Is TX Signal at
DCS / PCS In on
R819 OK?
Is signal on
C823 OK?
Is VPD_1800
signal OK?
Replace PA
Investigate
Mjoelner
Is signal at
DCS / PCS
Input of Z601
OK?
Replace
L801
Are Z601
Control lines
as per table?
Check RF
Connector
X602. OK?
Replace
Antenna
Switch
Replace RF
Connector.
Is TX Signal
at L705 OK?
Are TX I & Q
Signals OK?
Are TXP &
TXC OK?
Change
UEM
Change
UPP
TXC
U/S
TXP
U/S
Are Digital
I & Q Signals
OK at J213 &
J214
Is Vr2 2.8V
on R720?
Refer To Baseband
Fault Finding
Check T701
& Associated
Components.
YES
NO
YES
NO
YES
NO
NO
YES
NO
NO
YES
NO
YES
NO
YES
NO
YES
YES
YES
YES
NO
Test With
Spectrum
Analyzer
Test With
Oscilloscope
Check /
Inspect
End
Action
KEY
Change UEM.
OK?