Ericsson T28S Troubleshooting Manual page 8

2.3 Connect a call at –68.5dBm input signal and power
level 5
If you are able to connect a call, go to section 2.4.
If you are not able to connect a call, measure the resistance from VBATT to ground at the
Battery Connector (Fig.2.2). It should be more than 20 kohms. If the resistance is less, usually
only a few ohms there is probably a short circuit in N400.
If there is a short circuit in N400, send the unit on according to the local company directives.
Open the phone and check for liquid damage.
Make sure the antenna connector (W100, Fig. 2.1) is not incorrectly soldered, mechanically
damaged, dirty or oxidised. Clean, re-solder or replace if needed.
Check the solder joints on N351.
Try to connect a call again.
If you were able to connect a call, go to section 2.4.
If you still are not able to connect a call, send the unit on according to the local company
directives.
2.4 Read the Rx-level while call is connected
Make sure the output power is 31-35 dBm, if the Rx-level value is 40 - 46 steps.
If that is correct there is probably nothing wrong with the phone.
Lower the input signal to –102 dBm and make sure the Rx-level value is 6-12 steps and the
Rx-quality value is 0-2 steps.
If RX-level and Rx-quality is correct, try to run the phone through the test again.
If the phone passes the test but you are not able to connect a call towards the "real" net, make
sure the phone has not been locked out of the system due to theft.
If Rx-level is correct and Rx-quality is high, send the unit on according to the local company
directives.
If the Rx-level value is too high the phone needs to be calibrated.
If the Rx-level value is less than 38 steps with an input signal of –68.5 dBm or less than 5
steps at an input signal of –102 dBm then the fault is Rx-related.
4/00021-2/FEA 209 544/19 E
Fig. 2
2.
Trouble Shooting Guide, Standard
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