LG C3400 Service Manual page 77

4. Troubleshooting
Checking Flow
Does the SIM cards
supports 3V ?
YES
Voltage at pin1 of
J300 is 2.85V?
YES
Change the SIM Card
And try again.
Does it work
YES
Change SIM Card
START
NO
NO
NO
Properly?
Change the SIM Card. Our phone
supports only 3V SIM card.
Voltage output
of VSIM LCD
Is 2.85V?
YES
Replace J300
Redownload SW.
Does it work
Properly?
YES
SIM Card will be detected.
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YES
Resolder J300
NO
Change the main board