Ericsson A1018S - GSM 900 Only Service Troubleshooting; GSM 1800 Only Service Troubleshooting

A1018s/A1018sc Standard Electrical Repair
4/00021-2/FEA 209 544/16.B 6 (42)
Fig. 2.1
2.3 The phone only gets serv at GSM 900.
Open the phone and check for liquid damages.
Check the soldering at N330 (class B), N332 (class B) and N202:40,41 (class C)(all
in fig.2.1).
Replace N330.
If the fault remains, send the phone to the next repair level.
2.4 The phone only gets serv at GSM 1800
Open the phone and check for liquid damages.
Measure the resistance of N203:5 (class B, fig 2.1) to ground. The resistance should
be high (>1 Mohm). If it is considerably low (a few ohm), is the fault probably due
to Z200 (class B).
Check the soldering at N331 (class B), N333 (class B) and N202:43,44 (class C)(all
in fig.2.1).
Replace N331.
If the fault remains, send the phone to the next repair level.