Panasonic KX-FP81BX Service Manual page 66

KX-FP81BX / KX-FP81CX / KX-FP82CX
2.3.6.1. DIGITAL BLOCK DIAGRAM
You also need to check the signal lines listed here [List 1] when the unit fails to boot up the system. Those signal lines should
remain normal. Other signal lines are not directly related to that failure even if they have faults or troubles.
As long as these signals remain normal, once the power is turned on, each IC can repeatedly output 5V (H) and 0V (L). The
following shows NG and normal wave patterns.
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