Troubleshooting Diagram For Gsm900 Receiver - Nokia NHM-1 Series Troubleshooting Instructions

CCS Technical Documentation

Troubleshooting diagram for GSM900 receiver

Phone in continuous mode, AGC setting 12
Apply –90dBm
942.46771 MHz
signal from generator
to antenna connector.
Yes
No
Oscilloscope at RxI:
- Signal 160mVpp
- DC offset 1.35V**
- Frequency 67.7kHz
Yes
GSM900 Rx
chain functional
Issue 1 11/03
Yes
Change Spectrumanalyzer:
generator Antenna switch
level outputs, GSM900
–50dBm –88dBm
Yes
Spectrumanalyzer:
Helgo inputs
GSM900 –89dBm
Yes
Oscilloscope:
- VR1A, VR2, VR3,
VR4, VR5, VR7
- Check Helgo
serial interface
(burst mode)
Yes
Spectrunanalyzer:
4G VCO out
3769.6 MHz
–30dBm (*
Yes
Check Helgo
Figure 9: GSM900 receiver troubleshooting
Nokia Corporation.
Troubleshooting instructions
No
Spectrumanalyzer:
Antenna switch
input –84dBm
Yes
No
Oscilloscope:
VANT_1 = 0V
VANT_2 = 0V
Yes
Check Antenna
switch Z500
No
Check L633, L634
No
Check Baseband
No
Synthesiszer
trobleshooting
NHM-1
No
Check C575
No
Oscilloscope:
Check Helgo
serial interface
(burst mode)
Yes
Check Helgo
All spectrumanalyzer
reading values are
measured with 2.5 kOhm
passive probe (use
tweezers to connect the
probe ground to the nearest
PWB ground). Reading
value is represented without
+34dB compensation
(* Spectrumanalyzer
reading with 1kOhm
passive probe (right
value add +26dB)
**DC-level of RxI/RxQ in
continuous mode will
decrease slowly. The
original level can be
restored by rewriting
gain set.
Page 17
Check
baseband