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Trouble Shooting Guide, Advanced
If the output power is too low, measure the control voltage POWLEV at N450: 11 using an
oscilloscope Fig. 17.2.
Fig. 17.2
If the control voltage is too low, the fault usually is due to N800.
It can also be due to D600.
If the control voltage is correct, measure VREG at N450 pin 4 or N401 pin 3 +~3V, same
frequency.
If VREG is too low, replace N450. If that does not solve the problem, replace N401.
If VREG is correct, measure the signal TXIN at N560 pin 1 ~13 dBm.
If the signal TX is correct at N560, check the output signal from N401 pin 18,19.24 or 25
~26dBm.
If the signal is too low, replace N401.
If it is correct, continue checking the signal against the antenna connection and compare to a
reference board.
If the signal TX is too low at N560 pin 1, measure the feed voltage at N560: 6 using an
oscilloscope ~3.8 V, 215 Hz.
If the feed voltage is correct, replace N560. If that does not help, replace N401.
If the feed voltage is incorrect, the fault usually is due to anyone of V560, V561 or V562.
All the mentioned signal strength levels are approximate, especially when measuring at the
signal before the power amplifier, since the output power of the power amplifier is
radiated back to the probe.
You have to remember this when comparing the measured values with a reference.
4/00021-3/FEA 209 544/18 B
77(121)
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