Panasonic KX-FP80C, Service Manual

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the signal check in exactly the same order as in [List 1]. (If the ASIC fails to access the ROM, the
ASIC cannot access SRAM or DRAM normally.)
The digital circuit actually operates according to the timing combinations of these signals. If the
timing of these signals is even slightly delayed, the circuit will not work. Nor will it if the IC is
defective and the output voltage level is not normal although the timing of these signals is
accurate enough to meet the specifications. (Make sure that your oscilloscope is calibrated
before starting a test.)
Therefore, it is imperative to confirm whether each IC outputs the signal at the correct level. (See
the I/O Pin No. Diagram.) The signal level should be constantly output at between 5V (H) and 0V
(L) as described earlier.
Note:
Simply check the output level and make sure if the IC repeatedly outputs the signal at between
5V (H) and 0V (L).
I/O and Pin No. Diagram
After the power is turned on, the ASIC initializes and checks each IC.
The ROM, SRAM, and modem are checked.
If initialization fails for the ICs , the system will not boot up.
In this case, please find the cause as follows.
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