Denon AVR-X2400H Service Manual page 97

Check the I2C communication line.
YES
Check item(24). Check the I2C communication line :
Check the CPU.
Is the "I2C" waveform of the TP near the CPU [U1018] correct (like
the one shown in the diagram) when the power is turned on?
U1018
AVSDA AVSCL
YES NO
Check item(25). Check the I2C communication line :
Check GUI [U1026], HDMI SW [U1103] and CPU [U1018] patterns as well as soldering.
If there is no problem, go to the next step.
Check the CPU.
Remove the damping resistor [R1493/R1494]
of [U1018].
Is the "I2C" waveform correct?
YES
The GUI [U1026] is faulty.
Replace with a new device.
The GUI [U1026] is faulty.
Replace with a new device.
Recheck from check item (1).
If it does not work, replace the PCB.
*The diagram shows an example.
(Signal patterns vary depending on the
timing.)
Points for checking waveforms
- Crest value (3.3 V normally)
- Signal change
- SCL frequency (400 kHz normally )
Voltage scale：1.0V/div
Time scale：10us/div
NO The CPU [U1018] is faulty.
Replace with a new device.
97