Panasonic KX-FP80C, Service Manual

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Note:
1. Electrical continuity may have existed at the factory check, but a
faulty contact occurred as a result of vibration, etc., during
transport.
2. Solder waste remaining on the board may get caught under the IC
during transport, causing a short circuit.
Before we begin mass production, several hundred trial units are produced at the plant, various
tests are applied and any malfunctions are analyzed. (In past experiences, digital IC (especially
SRAM, DRAM and ROM) malfunctions are extremely rare after installation in the product.)
This may be repaired by replacing the IC, (DRAM etc.). However, the real cause may not have
been an IC malfunction but a soldering fault instead.
Soldering faults difficult to detect with the naked eye are common, particularly for ASIC and RA
(Resistor Array). But if you have an oscilloscope, you can easily determine the problem site or IC
malfunction by checking the main signal lines.
Even if you don’t have such a measuring instrument, by checking each main signal line and
resoldering it, in many cases the problem will be resolved.
An explanation of the main signals (for booting up the unit) is presented below.
What are the main signals for booting up the unit?
Please refer to 2.3.6.1. DIGITAL BLOCK DIAGRAM ().
The ASIC (IC501) controls all the other digital ICs. When the power is turned on, the ASIC
retrieves the operation code stored in the ROM (IC502), then follows the instructions for
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