Flow Chart No.3; Flow Chart No.4; Flow Chart No.5 - Denon DCD-720AE Service Manual

FLOW CHART NO.3

The luorescent display tube does not light up.
Is +3.3V_D2. voltage supplied to Pins(37) of F701?
YES
Is the voltage of approximately +42V supplied to Pin(38) of F701?
YES
Is the voltage of approximately +6V supplied to Pin(1),(43) of F701?
YES
Check the luorescent display tube control signal of ab microcomputer.
(VFD_RSTI,VFD_CE,VFD_CLK,VFD_DI)

FLOW CHART NO.4

+42V is not outputted.
Is approximately +42V voltage supplied to the kathode of D973?
YES
Check if there is any leak or short-circuit on the loaded circuit, and
service it if defective.

FLOW CHART NO.5

The key operation is not functioning.
Are the contact point and the installation state of the key switches
(S701-706) normal?
YES
When pressing each switches (S701-706), do the voltage of pin
(91),(92) of IC11 decrease?
YES
Replace IC11.
NO
Check the +3.3V_D2. line and service it if defective.
NO
Check the +42V line and service it if defective.
NO
Check the FL1/FL2 line and service it if defective.
NO
Check D973, D974, Q971 and periphery circuit, and
service it if defective.
NO
Re-install the switches (S701-706) correctly or replace
the poor switch.
NO
Check the switches (S701-706) and their periphery, and
service it if detective.
41