Ericsson PF 768 Troubleshooting Instructions page 9

PF768, Standard Electrical Repairs
• If the phone gets serv, proceed to section 2.3.
• If the phone doesn't get serv there is probably a LO-part fault or the losses in the
signal path are too great. It's also possible it could be a feed voltage fault.
If the fault remains, send the phone to the next level.
2.3 Connect a call towards the GSM test instru-
ment at power level 0 and –68.5dBm input
signal strength.
If you're able to connect a call, proceed to section 2.4.
If you're not able to connect a call, open the phone and check for liquid damages.
Make sure the back cover is intact and of the correct model since there are 2 models
(fig. 2.1).
Replace the antenna connector (if you haven't replaced it already) and try again.
Note that there are several different models of the antenna connector too and it's
important to mount the correct one.
• If you where able to connect a call, proceed to section 2.4.
The fault is probably Tx related or it's a feed voltage fault if you still aren't able to
connect calls.
If the fault remains, send the phone to the next level.
2.4 Read the Rx-level value from the instru-
ment while the call still is connected.
If the Rx-level value is at 42 2 steps, mak e sure the output power is 28-32dBm.
• The phone probably isn't faulty if that's correct.
Lower the signal from the instrument to –102.5dBm and make sure the Rx-level
value is 4-12 steps and that the Rx-quality value is 0-2 steps.
Try running the phone through the test again.
• If the phone passes the test but isn't able to connect a call towards the "real" net,
make sure the phone hasn't been locked out of the system due to theft. If it
hasn't, replace D600 (class B, fig. 2.3).
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