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Trouble Shooting Guide, Advanced
For some power levels can this make the output power or the DAC values ending up outside the
limits.
In that case, the fault usually is due to N401 or N450.
The fault can also be due to N800, N570 or D600.
If the output power is too low, measure the control voltage POWLEV at N450 pin1 using an
oscilloscope.
It should look like in Fig.8
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 +3.7 V
, same
DC
frequency.
If VREG is too low, the fault can be due to N450or N401.
If VREG is correct, measure the signal TX at N560 pin 1 ~12 dBm.
If the signal TX is correct at N560 pin 1, check the output power from N401 pin 19 ~27 dBm.
If the output power is too low, replace N401.
If the output power is correct at N401, follow it from the output of the power amplifier to the
antenna through V411, V205, Z204 and Z205.
The fault usually is due to the antenna switch connection V205 and V206 with the surrounding
components.
If the signal TX is too low at N560 pin 1, measure the feed voltage at N560 pin 3 using an
oscilloscope ~3.8 V, 215 Hz.
If the feed voltage is correct, the fault usually is due to N560 or N401.
If the feed voltage is incorrect, the fault usually is due to V560 or V561.
All the mention signal strength levels are approximates, especially when measuring at the
signal before the power amplifier, since the output power of the power amplifier radiates
back to the probe.
You have to consider this when comparing your values with a reference.
4/00021-3/FEA 209 544/18 B
41(121)
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