Nokia NPM-2NX Troubleshooting Manual page 42

NPM-2NX
Troubleshooting
3) Connect oscilloscope probe to one of the RX I/Q test points on PWB (all four testpoints
J808, J809, J818 and J819 are located behind display)
4) Measure frequency and peak-to-peak voltage of RX I/Q signal from each test points.
Signal should look like in the picture below:
- If only one or two testpoints shows correct signal and rest of the testpoints are either
deaf or signal is very small, the fault is probably due to Safari ASIC.
- If the signal amplitude is correct but its frequency is something else than 67.71 kHz +/
- 3 kHz, you may try to change AFC value (-1024...1023) and see does it have effect to
the frequency. Frequency should be tuned to target value with the AFC value of +/- 100.
- If the signal amplitude and frequency in all testpoints is correct and signal amplitude
changes when the LNA, MIX2 and BB gains are changed, RX chain is OK.
- If the signal amplitude in all testpoints is too low (< 1 Vp-p), you have to continue with
RX front-end measurements.
1) Set signal generator frequency to 1960.06771 MHz and level to -60 dBm.
2) Set spectrum analyzer settings as following:
Page 42 ãNokia Corporation
CCS Technical Documentation
Issue 1 07/02