ey circuit is simple, check the net is short or not. If the issue is still there, you need to check
item
ill be an echo at receiver that shows the microphone is
k. Otherwise you must check the microphone bias circuit, test bias voltage and output signal,
uld be 2.2k OHM.
4.1.6
chip with a headset. Then check
speaker resistances see if it’s 8ohm or not. If not, the speaker is bad. Otherwise you need to check audio
PA circuit. After repaired, you can test it on engineering mode again.
T-Flash card circuit is very simple, so you must pay more attention to card socket to see if it is
Soldered well.
4.1.4 Keys failure
K
The BB chip at last.
4.1.5 Voice cannot be sent or received
This often occurs in a mobile phone. You can enter into engineering mode by inputting *#060905#,
First you go to the test item “receiver”, and then you can hear “du du” sound if the receiver is good.
Otherwise you need to test its resistance with multimeter. It should be 32ohm. If the resistance is much
bigger it means the receiver is bad, so you can change for a good one. Second you go to the test
“echo” and test MIC. Huff at MIC then there w
o
Microphone resistance sho
No voice in speaker
First you can check if the audio source can output from baseband
4.1.8 T-Flash card failure
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