Power Amp (Amp Pcb); Analog Audio - Denon AVR-X6400H Service Manual

4.2. Power AMP (AMP PCB)

When using the protection pass mode, do not connect speakers to the speaker terminals.
No audio output.
Protection is activated.
YES
Is the power transistor open or short circuited?
DHCT-A3 / DHCT-C3
NO
Is the emitter resistor of the power transistor
open?
0.47 Ω
NO
Is the base resistor of the power transistor open?
47 Ω
NO
Is the trimmer potentiometer between the base
of the power transistor open?
300 Ω
NO
Are any other transistors faulty?
NO
Are any other resistors faulty?
NO
Turn on the power and, check that the voltage of each part is correct and that there is an idling cur-
rent.
YES
Replace the power transistor.
YES
Replace the emitter resistor.
YES
Replace the base resistor.
YES
Replace the trimmer potentiometers.
YES
Replace the transistor.
YES
Replace the resistor.

4.3. Analog audio

No audio output.
Are the [N9028 : 5 - 7pins] in the A.AUDIO/VIDEO
PCB receiving ± 7V?
YES
Does the audio signal flow to [N5833] on the L-
AMP CONNECT PCB and [N5821] on the R-AMP
CONNECT PCB?
NO
Is the serial data for electronic volume sent to
the DIGITAL PCB?
YES
Reconnect the connectors correctly.
If the malfunctioning channel and function can be identified, check the corresponding signal path.
90
NO
Repair the ± 7V power supply.
YES
Repair the power amplifier.
NO
Check the CPU.