Denon AVR-X6400H Service Manual page 102

Check the I2C communication line. (HDMI Tx)
YES
Check item(9). Check the I2C communication line :
Check the CPU.
Is the TP waveform of the TP near the HDMI SW1 [U2401] cor-
rect (like the one shown in the diagram) when the power is
turned on?
I2C(HSCL)
U2401
I2C(HSDA)
*The diagram shows an example.
(Signal patterns vary depending on the tim-
ing.)
Points for checking waveforms
- Crest value (3.3V normally)
- Signal change
- SCL frequency (400kHz normally)
Voltage scale : 1.0V/div
Time scale : 10us/div
YES
HDMI Tx [U3401] is faulty.
Replace with a new device.
YES
Recheck from check item (1).
If it does not work, replace the PCB.
NO
Check the HDMI Tx. Check the HDMI SW1.
Remove the damping resistor Remove the damping resistor
[R3425/R3427] of [U3401]. [R2460/R2461] of [U2401].
Is the "I2C" waveform correct? Is the "I2C" waveform correct?
YES YES
HDMI Tx [U3401] is HDMI SW1 [U2401] is
faulty. faulty.
Replace with a new Replace with a new
device. device.
Recheck from check item (1).
If it does not work, replace the PCB.
NO
Check item(10). Check the I2C com-
munication line :
Check HDMI SW [U2601 or U2401],
HDMI Tx [U3401] and CPU [U6201]
patterns as well as soldering.
If there is no problem, go to the next
step.
NO
Check the HDMI SW2.
Remove the damping resistor
[R2630/R2631] of [U2601].
Is the "I2C" waveform correct?
YES NO
HDMI SW2 [U2601] is The CPU [U6201] is
faulty. faulty.
Replace with a new Replace with a new
device. device.
102