Illumination And Buzzer - Ericsson GF 768 Troubleshooting Manual

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5. Illumination and buzzer

5.1 Type of fault.
Insert a dummy battery and a SIM card into the phone, press the On/Off key and wait for the phone to get serv
(with the test instrument or the GSM-net).
• If the phone doesn't beep at start, go to "Ring Vol" in the menu and try to raise the ring volume to the max (if
it already is at max, lower it and raise it to the max again). If there's no sound or if the sound is faint, go to 5.2.
• If the background illumination for the display doesn't light up at start, go to 5.3.
• If the background illumination for the keyboard doesn't light up at start, go to 5.4.
• If the top indicator doesn't blink green when getting serv, go to 5.5.
When getting serv and the top indicator blinks green, lower the battery voltage to 4.2V. The top indicator should
blink red, the battery indicator in the display should show an empty blinking battery and the phone should warn
with a beep.
• If the top indicator doesn't blink red, the battery indicator doesn't show an empty blinking battery and the
phone doesn't warn with a beep, the phone needs a battery calibration.
• If the battery indicator shows an empty blinking battery and the phone beeps but the top indicator doesn't
blink red, go to 5.6.
• If both red and green top indicator are faintly glowing and the buzzer sounds faintly, go to 5.7.
5.2 Buzzer faint or dead.
Open the phone and check for water damage.
The front side of the circuit board is shown in fig. 5.1.
Make sure the solderings at the buzzer, H600 (class A, fig. 5.2), are correct.
• If the solderings are correct, replace the buzzer. Assemble the phone and try the buzzer again as in 5.1. If the
fault is fixed, send the phone back into the normal flow.
If the fault remains, disassemble the phone, give the board power and start it up.
Measure the voltage at H600 pad 4 (~3.4V, fig. 5.2).
Fig. 5.1
Troubleshooting guide
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