CCS Technical Documentation
RF Troubleshooting
Company Confidential
NEM-4
Issue 1 09/2003
Copyright
2003 Nokia Corporation.
Page 6(b)-83
Company Confidential
•
The power amplifier is getting a correct VBATRF supply via L805 & L809.
•
Mjoelner’s supply voltages VR1A, VR2, VR3, VR4, VR5 & VR7 are all working cor-
rectly.
General instructions for GSM1800/1900 TX Troubleshooting
Apply an RF-cable to the RF-connector to allow the transmitted signal to act as normal.
RF-cable should be connected to measurement equipment (GSM Test equipment, Power-
meter, Spectrum Analyzer, or similar).
DCS 1800/PCS 1900 Tx fault finding flow chart
The following diagram assumes the following:
•
Phoenix has been set up as shown previously (selecting DCS 1800 in the RF con-
trol box).
•
Relevant components have been visually inspected for orientation, placement
etc.
•
The Transmit Signal has been checked with a Spectrum Analyzer at the RF con-
nector, X602 and was found to be low or non-existent.
•
The VCO is running correctly.
•
The Power Amplifier is getting a correct VBATRF supply via L805 & L809.
•
Mjoelner’s supply voltages VR1A, VR2, VR3, VR4, VR5 & VR7 are all working cor-
rectly.
START
Is EGSM
TXIN signal
at R805 OK?
Check Z701 &
Biasing components
NO
Is Signal at
C733 OK?
Is signal at
L807 OK?
YES
Are TX I & Q on
C715 & C716. OK?
Are digital I & Q
signals OK on
J123 & J214?
Change
Mjoelner
Are TXP &
TXC visible?
Change
UPP
Change
UEM
NO
TXC
NO
TXP
Is VR2
2.8V on
C731?
Is VTXB
_900 OK?
Is Signal at V802
Collector OK?
Check / Replace
R805, C820, C821
Check V802 &
associated components
Is Signal
at C834
OK?
Probe VPD_900Signal
on R818 and set Power
Level to 19 using Phoenix.
Is Pulse Pk-Pk 2.8V?
Replace PA
Is Signal at
TX_GSM on
L801 OK?
Change
L801
Check Antenna
Switch Control
Lines. Do they
match the results
in the table?
Check L701,
L702 & L703.
OK?
Replace
Inductors
Is Signal at
Antenna pin
of Z601 ok?
Change X602
RF Connector
Change
Antenna
Switch
Test using
Spectrum Analyzer
Test using
Oscilloscope
Check /
Inspect
End
Action
KEY
YES
YES
NO
NO
NO
YES
NO
YES
YES
YES
NO
NO
YES
YES
NO
NO
YES
YES
NO
YES
NO
NO
YES
NO
YES
YES
NO
R 806
R
R 806
Change UEM?
OK?