Denon AVR-X4400H - Page 112

Check item(20). Check the I2C communication line :
Check the CPU.
Is the "I2C" waveform of the TP near the CPU [IC151] correct (like
the one shown in the diagram) when the power is turned on?
IC401
TP110 (CK)
TP111 (DA)
Check item(21). Check the I2C communication line :
Check GUI [IC401], VIDEO Decoder [IC351] and FET [Q1505] patterns as well as soldering.
If there is no problem, go to the next step.
Check the I2C communication line again after replacing the FET [Q1505].
If there is still a problem, the GUI [IC401] is faulty.
Replace with a new device.
Check the I2C communication line.
The GUI [IC401] is failure.
Replace with a new device.
YES
*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
NOYES
Recheck from check item (1).
If it does not work, replace the PCB.
112
Caution in
servicing
Electrical Mechanical Repair Information Updating