Network Problems - Ericsson A2618s Troubleshooting Manual

2 Network Problems

2.1 Find out if the fault is RX- or TX-related
Connect the unit (with signalling program) to a GSM test instrument and try to get
SERV at an input signal strength of -68.5 dBm.
If the unit does not get SERV, go to section 2.2.
If the unit gets SERV, go to section 2.4.
2.2 The phone does not get SERV
Open the unit and check for liquid damage.
No action is to be taken for a liquid damaged unit, send the unit on according to the local
company directives.
Make sure that the antenna connector W1 not is mechanically damaged, dirty or oxidised.
Clean it if needed.
Check the soldering of N200, N201, Z200 and Z201.
Measure the resistance over L202, L203, L204 and L206 (0 ohm).
Measure the resistance over L200, L201 (0 ohm) and R202 (270 ohm).
Replace if incorrect.
Retry to get SERV again with the settings mentioned above.
If the unit gets SERV, go to section 2.4.
If the unit still does not get SERV, the fault probably is within the LO part, or the losses in the
signal path are too large.
It is also possible that the feed voltages are incorrect, section 2.3.
Open the unit.
Power up the board and start it by pressing the On/Off key.
Measure the VRAD-voltage on C705, measure on the side close to C706.
If the voltage is incorrect, send the unit on according to the local company directives.
Measure the V380B-voltage on C706, measure on the side close to R705.
If the voltage is incorrect, send the unit on according to the local company directives.
If the voltage is correct, measure the VVCO-voltage on pin 5 of N701.
If the VVCO-voltage is correct, measure the resistances over R362 (18 kohms) and R392 (82
ohms).
If the resistances are incorrect, replace the corresponding component.
If both the resistances are correct, go to section 2.3.
4/00021-2/FEA 209 544/25 A
Trouble Shooting Guide, Standard
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