Denon AVR-S740H - Page 87

YES
YES
YES
Check the I2C communication line. (HDMI Rx/TX)
Check item(8). Check the I2C communication line :
Check the CPU.
Is the "I2C" waveform of the TP HDMI Rx/Tx [IC721] correct (like
the one shown in the diagram) when the power is turned on?
IC701
P_CK
P_DA
HDMI Rx/Tx [IC721] is
faulty. Replace with a
new device.
HDMI SW [IC701] is
faulty. Replace with a
new device.
CPU [IC751] is faulty.
Replace with a new
device.
HDMI Rx/Tx [IC721] is faulty.
Replace with a new IC.
Recheck from check item (1).
If it does not work, replace the PCB.
Check item(9). Check the I2C commu-
nication line :
Check HDMI Rx/Tx [IC721], CPU[IC751]
patterns as well as soldering.
If there is no problem, go to the next
step.
Check the HDMI SW.
Remove the damping resistor
[R7147/R7149] of [IC701].
Is the "I2C" waveform correct?
Recheck from check item (1).
If it does not work, replace the PCB.
Check the HDMI Rx/Tx.
Remove the damping resistor
[R7229/R7231] of [IC721].
Is the "I2C" waveform correct?
NO
NO
YES YES NO
*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
Before Servicing
This Unit
Electrical Mechanical Repair Information Updating
87