LG -MC2670 Service Manual page 39

LG-MC2670
Checking Flow
SETTING : "Ringers" at Sounds menu
START
Voltage at Pin6 of
U401 is over
3.4~4.2V?
Yes
Does Speaker work Properly?
Yes
The R423(SPK_EN) is High?
Yes
The Pin6 of U402 is
High : Speaker mode
Low : Receiver mode
Check the signal
level at L406, 407
Yes
NO
Change main board.
Internal pattern is opened
NO
Check the contact of speaker or
Replace the speaker
NO
Check the
soldering R423
Yes
Replace the MSM or Board
NO
Check the soldering
L406, L407
Yes
Check the signal
level of EAR10+ at
R422, R430
Yes
Check the signal
level at Pin4 of
U401
Yes
Does U401 work
properly?
Yes
Speaker will work properly
36
NO
Re-soldering R423
NO
Re-soldering L406, L407
NO
Replace the MSM
NO
Re-soldering or
Replace the U402
NO
Re-soldering or
Replace the U401