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15 No Serv, or Not Able to Connect a Call
15.1 Find out if the fault is related to RX or TX
Connect the phone to a GSM test instrument. GSM test set must be set as active base station and
use a test SIM for best result.
Attach a dummy battery and antenna cable.
Start the test program.
Go to MISC \ Go to call processing.
Start the signal part in the test program using the commando mentioned above. Before the phone
enters the signal mode, there will occur a window telling you to perform "Reset MS"
afterwards.
Try to get serv at - 68.5 dBm input signal.
If the phone cannot get serv, go to section 15.2.
If it can get serv, go to section 15.3.
15.2 The phone cannot get serv
If the phone can not get serv, then the fault probably is somewhere in the LO-part or the losses
in the signal path are too large.
Open the phone and check for liquid damages.
No further action should be taken for a liquid damaged telephone.
Attach the board to the fixture and start the test program.
If you want to continue to trouble-shoot after signal test, perform "Reset MS" as follow:
Cut the battery voltage to the phone.
Set the battery voltage again.
Start the phone using a pulse on DCIO or the On/Off button.
Click on "Reset MS". It will occur a message window that tells you to start the phone.
Click on OK.
The test program is running again.
For GSM 900:
Set Radio in RX Static mode on channel 62.
Set RX amplitude from the GSM test set to 947.4 MHz and -50 dBm.
Make sure the RX amplitude really is -50 dBm over Z205 pin 5 using a spectrum analyser.
Raise or lower the amplitude on the GSM- test set if necessary.
We propose the following settings on the spectrum analyser when measuring the transmitter:
CF- 947.4 MHz, SPAN- 1 MHz, RBW- 10 kHz, VBW- 10 kHz and Sweep- 30 ms.
For GSM 1800:
Set Radio in RX Static mode on channel 699.
Set RX amplitude from the GSM test set to 1842.6 MHz and -50 dBm.
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Trouble Shooting Guide, Advanced
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