Panasonic KX-FLB758RU Service Manual page 94

KX-FLB758RU
6.5.6.2. CALL SERVICE 2
"CALL SERVICE 2" means that the synchronous signal out of the LSU cannot be detected.
The synchronous signal out of the LSU is detected by IC 610-89pin. (XHSYNC)
Note:
As for the "Pulse" waveform of the above flow chart, see the timing chart.
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