Tone Dialing Problems; No Ringing Sound When Ring Signal Is Input - Panasonic KX-TS880MXB Service Manual

KX-TS880MXB/KX-TS880MXW
8.3.

Tone Dialing Problems

Can the DTMF sound
be monitored ?
Does the DTMF signal
appear at base of Q422?
Check Q422, Q107.
8.4.

No Ringing Sound When Ring Signal is Input

Call the unit from another telephone.
Does a sine wave of approximately 60V
or more appear across Tip and Ring?
Is the voltage across Pin 8 and Pin 2 of
IC1 30 Vp-p?
Does the tone ringer output signal
appear across Pin 5 and Pin 2 of IC1?
Check the Ringer SW2, PC1, C5 and T1
NO
YES
YES
NO
YES
YES
YES
Does the DTMF signal
appear at Pin91 of IC801?
YES
Check C485, R487, R490,
C415, L411, L409 and
Q403.
Check R481, R485, R486,
R488, C483, R483, L421
and R430.
NO
Check the telephone line.
NO
Check C1, R1, R2, D1,
and LED1.
NO
Check IC1, R3, R4, C3 and
C4.
14
NO
Check IC801 and X1.