Denon DCD-F109 - Flow Chart No. 3: Display Issues; Flow Chart No. 4: Key Operation Issues

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The key operation is not functioning.
When pressing each switches (S500-506), do the voltage of pin
(4),(5),(6),(99),(100) of IC11 decrease?
Are the contact point and the installation state of the key switches
(S500-506) normal?
Replace IC11.
Re-install the switches (S500-506) correctly or replace
the poor switch.
Check the switches (S500-506) and their periphery, and
service it if detective.
NO
NO
YES
YES
FLOW CHART NO.4
Is +3.3V_D voltage supplied to Pins(37) of FLT500?
Is the voltage of approximately +42V supplied to Pin(38) of FLT500?
The uorescent display tube does not light up.
Is the voltage of approximately +3.3V(AC) supplied to Pin(1)-Pin(43)
of FLT500?
Check the uorescent display tube control signal of ab microcomputer.
(FL_RST,FL_CS,FL_CLK,FL_MDT)
Check the +3.3V_D line and service it if defective.
Check D619,D620,ZD605,ZD606,Q608 and the periphery
circuit, and service it if defective.
NO
NO
Check the FL1/FL2 line and service it if defective.
NO
YES
YES
YES
FLOW CHART NO.3