Panasonic EASA-PHONE KX-T2355 Service Manual And Technical Manual page 17

_ 3. PULSE DIALING PROBLEMS
NO
Can a pulse sound |
be monitored? |
YES
Does the voltage ©
across Tip (T) and
Ring (R) rapidly
switch between 48 V
and 10 V?
Check D6, SA1, Q1,
Q2 and Q8.
YES
Does Pin 16 output
ae ICt.. | the dial pulse? | Check C1.
| YES
Do pulses (0.6
Vp-p) appear at
the base of Q2?
YES
— Check Q8.
Check Q1, D6, SAT
and Q2.
4. TONE DIALING PROBLEMS
Does a DTMF signal
appear at Pin 25 of
C1?
Can the DTMF
sound be
monitored?
Check IC1.
Are the DTMF
signals composed of
2 frequencies? |
Does the DTMF
signal appear at the
collector of Q3?._
Check IC1. Check Q3 and Q10. |
Check Q1, Q2, R8,
D6 and SA1.