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Trouble Shooting Guide, Advanced
Fig. 15.3
If it looks like the one in the figure, but the phone cannot connect a call, is it a logical related
fault and usually depends on D600 or N800.
If the spectra does not look like the figure, is it either one of the modulation signals, MODQN,
MODQP, MODIN, MODIP, missing from D600 or a faulty low pass filter to the modulation
signals (R642, R643, R644, R645, C105, C106, C114, C115).
Measure with an oscilloscope on the capacitors.
The signals are sinus shaped with the frequency 67.7 kHz and amplitude ~2.5 V p-p.
Compare the signals with each other.
The fault is on the modulation signal that is different from the other.
If the modulation signals look good and are in the right phase (90 degrades turned compared to
each other) then the fault can be caused by N500.
15.4 Read the RX level value from the instrument while the
call is still connected
If the RX level value is at 40- 46 steps, make sure the output power is 31-35 dBm GSM 900,
power level 5 or 28-32 dBm GSM 1800, power level 0.
If the value is correct there is probably nothing wrong with the phone.
Lower the input signal for GSM 900 to:
-102 dBm, and make sure the RX level is at 6- 12 steps and the RX quality is at 0- 2 steps.
For GSM 1800 should the input signal be:
100.5 dBm, and the RX level 7-13 and the RX quality 0-2 steps.
If these values are correct, is the phone probably without fault, try to run the phone trough the
test again.
4/00021-3/FEA 209 544/18 B
70(121)
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