Trouble Shooting Guide, Advanced
4/00021-3/FEA 209 544/25 C
Ericsson Mobile Communications AB
69(78)
20 Buzzer
20.1 How to find the fault
Power up the board and start it in EFRA with the test program.
Go to Audio/Audio/Buzzer.
Activate the buzzer with “Buzzer ON” Fig. 20.1.
Fig. 20.1
Fig. 20.2
Measure the signal at X850: 4, Fig.20.2, (a serrated-negative signal 0.5V) when the buzzer is
activated.
Also check that there is VBATT at X850: 3.
If there is no signal at X850: 4, measure at R851 (a squared wave signal 2.5V).
If there is a signal at R851 the fault probably is due to V851.
If there is no signal at R851 at the side toward the processor, the fault is due to D600
or a foil damage.