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Trouble Shooting Guide, Advanced
If the frequency is misplaced, try to lower the "Adjust sweep current" until the frequency of the
transmitter has locked on.
If the transmitter locks on, start it in switched mode on channel 62 with DAC 7 value on "FF".
Check if there is an output power 30 - 35 dBm at the antenna plate using the spectrum analyser.
We propose following settings on the spectrum analyser while measuring:
CF- 902.4 MHz, SPAN- 0 MHz, RBW- 300 kHz, VBW- 100 kHz and Sweep- 0.8 ms.
If the output power is correct then the transmitter is without fault.
Try to test the phone again.
If there is no switched output power at all or if it is too low, go to chapter "No serv".
If the transmitter does not lock on, change the CF on the spectrum analyser to 772,4 MHz.
Check the frequency and the amplitude on the LO-signals LOINA and LOINB at N201pin 18,
17 ~ -10 dBm.
If the amplitude and the frequency are correct, go to section 3.1.
If the frequency is correct, but the amplitude is too low, check the feed voltage at N303 pin 6
+3.7 V
.
DC
If the voltage is correct, replace N303.
If the voltage is incorrect, check VVCO +3.8 V
, SYNTON_GSM +3.7 V
and V305 with the
DC
DC
associated components.
If SYNTON_GSM is missing, check D103, D105 and D600.
If the amplitude is correct, but the frequency is incorrect, the fault usually depends on N301. It
can also depend on N303 or D600.
If the signal is several MHz wide, replace C318.
To measure the frequency more precisely you can lower SPAN to 1 MHz.
For GSM 1800:
Start the transmitter in static mode on channel 699 and check the transmitters output power and
frequency.
We propose the following settings on the spectrum analyser while measuring:
CF- 1747.6 MHz, SPAN- 200 MHz, RBW- 10 kHz, VBW- 10 kHz and Sweep- 30 ms.
Check the frequency of the transmitter 1747.6 MHz.
If the frequency is misplaced, try to lower the "Adjust sweep current" until the frequency of the
transmitter has locked on.
If the transmitter locks on, start it in switched mode on channel 699 with DAC 7 value on "FF".
Check if there is an output power 28 - 32 dBm at the antenna connector on the board, using the
spectrum analyser.
We propose the following settings on the spectrum analyser while measuring:
CF- 1747.6 MHz, SPAN- 0 MHz, RBW- 300 kHz, VBW- 100 kHz and Sweep- 0.8 ms.
If the output power is correct then the transmitter is without fault.
Try to test the phone again.
If there is no switched output power at all or if it is too low, go to chapter "No serv".
If the transmitter does not lock on, change the CF on the spectrum analyser to 1669.6 MHz.
Check the frequency and the amplitude on the LO-signals LOINA and LOINB at N202 pin13,
14 ~ -10 dBm.
4/00021-3/FEA 209 544/18 B
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