Ericsson GF 768 Troubleshooting Manual page 42

Troubleshooting guide
8.4 Read the Rx-level value from the instrument while call is connected.
If the RX-level value is at 43 3 steps mak e sure the output power is 31-35dBm.
• If it is, the phone probably isn't faulty. Lower the signal strength to –102dBm and make sure the Rx-level is 6-
12 steps and that the Rx-quality is 0-2 steps.
Try running the phone through the test again.
• If the phone passes the test but doesn't connect calls mad in the "real" mobile network, make sure the phone
hasn't locked out from the system due to theft. If it hasn't, replace D600 (class B, fig. 8.4).
If the output power is too low or the Rx-quality value is too high, send the phone to the next level.
The phone needs calibration if the Rx-level value is too high and therefore you have to send it to the next level.
If the Rx-level is below 38 steps at –68.5dBm signal strength or below 5 steps at –102dBm signal strength,
the fault is Rx-related.
Open the phone and check for water damage.
Make sure the back cover is intact and of the correct model since there is two kinds. Fig. 8.1 shows what kind of
back cover is to be used with which board.
Replace the antenna connector (if it hasn't been replaced yet) and try again. Note that there are different models of
the connector. It's important that you don't assemble the wrong one. Fig. 8.2 shows the different kinds of connec-
tors and which boards they belong to.
If the fault remains, open the phone.
Measure the resistance to ground from the marked side of C416 (fig. 8.3, >100 kohms).
• If the resistance is too low, replace Z200 (class B, fig. 8.3). The resistance usually becomes a few ohms when
Z200 breaks.
If the fault remains, send the phone to the next level.
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Fig. 8.4