Troubleshooting Diagram For Gsm1800 Receiver - Nokia NHM-1 Series Troubleshooting Instructions

NHM-1
Troubleshooting instructions

Troubleshooting diagram for GSM1800 receiver

Phone in continuous mode, AGC setting 12
Apply –90dBm
1842.86771 MHz
signal from generator
to antenna connector.
Yes
No
Oscilloscope at RxI:
- Signal 140mVpp
- DC offset 1.35V**
- Frequency 67.7kHz
Yes
GSM1800 Rx
chain functional
Page 18
Yes
Change Spectrumanalyzer:
generator Antenna switch
level outputs, GSM1800
–50dBm –87dBm
Yes
Spectrumanalyzer:
Helgo inputs
GSM1800 –88dBm
Yes
Oscilloscope:
- VR1A, VR2, VR3,
VR4, VR5, VR7 = 2.7V
- Check Helgo
serial interface
(burst mode)
Yes
Spectrunanalyzer:
4G VCO out
3769.6 MHz
–30dBm (*
Yes
Check Helgo
Nokia Corporation.
CCS Technical Documentation
No
Spectrumanalyzer:
Antenna switch
input –84dBm
Yes
No
Oscilloscope:
VANT_1 = 0V
VANT_2 = 0V
Yes
Check Antenna
Switch Z500
No
Check L635, L636
No
Check Baseband
No
Synthesiszer
trobleshooting
No
Check C575
No
Oscilloscope:
Check Helgo
serial interface
(burst mode)
Yes
Check Helgo
All spectrumanalyzer
reading values are
measured with 1 kOhm
passive probe (use
tweezers to connect the
probe ground to the nearest
PWB ground). Reading
value is represented without
+26dB 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.
Issue 1 11/03
Check
Baseband