KX-AT7730RU - Panasonic Telephone Service Manual (repair manual). Page 19

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19
KX-AT7730 Series
7.3.
SPEAKER-PHONE TROUBLE
Press the speaker-phone button 
and create a dial tone.
No
No
Yes
Yes
OK
Yes
Yes
Does the dial tone sound from
the speaker-phone?
Input signal from the MIC.
Does the dial tone reach at Pin27
of IC3?
Does the dial tone reach
at Pin19 of IC3.
Yes
Check C63 speaker.
Check R57, C61, C62, IC3.
Yes
No
No
Does the dial tone reach at 
collector of Q4?
Check C42, C46, R42 and Q13.
No
Is it possible to send a signal
from the MIC?
Does a signal reach at 
Pin4 of IC3?
Check C41, R41 and Q3.
Check IC3, C64, R206, C59, 
R45, C48 and Q14, MIC.
Check Q3.
Does a dial tone sound  
from the Handset speaker.
Yes
Change the Volume of sp-phone.
Is   mark indicated more than
three on the LCD?
Check Q12, CN7, CN8, JK3.
No
No
No
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