Check item(15). Check the I2C communication line :
Check the CPU.
Is the "I2C" waveform of the HDMI OSD [IC731] correct (like the one
shown in the diagram) when the power is turned on?
IC731
A_DA
A_CK
Check item(16). Check the I2C communication line :
Check HDMI OSD [IC731], CPU[IC751] patterns as well as soldering.
If there is no problem, go to the next step.
Check the HDMI Rx.
Remove the damping resistor [R7323/R7324]
of [IC731].
Is the "I2C" waveform correct?
CPU [IC751] is faulty. Replace with a new
device.
Check the I2C communication line.
Recheck from check item (1).
If it does not work, replace the PCB.
OSD[IC731] is faulty.
Replace with a new device.
YES
*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
YES
YES
NO
84
Caution in
servicing
Electrical Mechanical Repair Information Updating
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