Nokia 7600 - GSM900;1800 Tx Troubleshooting

CCS Technical Documentation 6-Troubleshooting
Company Confidential NMM-3
Issue 1 (11/2003) Copyright  2003 Nokia Corporation Page 6-17
Company Confidential
GSM900/1800 TX Troubleshooting
Replace faulty
component
Tx OK
Check output signal level
from antenna conncetor
+32.5dBm @ 897.4MHz (GSM900)
+29.5dBm @ 1747.8MHz (GSM1800)
OK ?
Check all
power levels
OK ?
Tune Tx
power levels
OK ?
Tx signal found ?
Check output signal
on 500MHZ span
Signal found on
correct frequency ?
Synthesizer
troubleshooting
HELGO
troubleshooting
Check with RF probe signal
level on PA input
+0dBm on 900 PA i/p
-1dBm on 1800 PA i/p
OK ?
Start Tx power level tuning
and check tuned DAC values:
Highest level ~700 (GSM900)
Highest level ~600 (GSM1800)
Lowest level ~170
Base level ~150
Major differences ?
Check with oscilloscope
900 & 1800 PA CONTROL
VPCTRL >1.5V max
C564/C565
OK ?
PA & ant. switch
troubleshooting
Check Tx filter/
Tx balun input level
-4dBm on 900 FILT i/p
-4dBm on 1800 BALUN i/p
OK ?
Tune TX DAC
values
Check power control
loop components
OK ?
Replace faulty
component
Replace HELGO
Yes
Yes
No
Yes
No
Yes
No
No
No
Yes
No
Yes
Yes
Yes
No
No
Yes
No
Yes
No
Phoenix Settings:
Band = GSM900/GSM1800
Active Unit = Tx
Op Mode = Burst
Tx Chan = 37 GSM900
Pwr Lvl = 5
Tx Chan = 700 GSM1800
Pwr Lvl = 0
PA Mode = Free
Tx Data Type = Random
Yes