Transmitter Troubleshooting Diagram - Nokia NHM-1 Series Troubleshooting Instructions

NHM-1
Troubleshooting instructions

Transmitter troubleshooting diagram

Tx troubleshooting
Check output signal level
~ 32.5 dBm @ 897.4MHz(GSM900)
~ 29.5 dBm @ 1747.8MHz(GSM1800)
OK?
No
Tx signal found?
Yes
Check with RF probe:
Signal level on PA input > 0dBm (*
OK?
Yes
Start Tx power level tuning
and check tuned DAC values:
Highest level ~ 700
Lowest level ~ 170
Base level ~ 150
Major differences?
No
Check with oscilloscope:
PA ctrl voltage > 1.5 peak,
OK?
Yes
PA & ant. switch
troubleshooting
Page 10
Tx OK
Yes
Yes
Check all
power levels,
OK?
No
Check output signal
on 500 MHz span.
Signal found on
incorrect frequency?
No
troubleshooting
No
*(When 1kOhm passive probe is used
correct measurement result by +26dB
Yes
Tune Tx DAC values
Check control loop
components,
OK?
No
No
Replace faulty
component(s)
Figure 4: Transmitter troubleshooting
Nokia Corporation.
CCS Technical Documentation
Yes
No
Tune Tx
power levels
Yes
troubleshooting
Helgo
Yes
No
OK?
Synthesizer
Replace Helgo
Issue 1 11/03