Check item(40). Checking the reset. :
Check the CPU.
Is the waveform of the TP near the OSD(IC731)97pin) correct (like
the one shown in the diagram) when the power is turned on?
97pin
Check item(41). Check the I2C communication line :
Check the CPU.
Is the "I2C" waveform of the TP near the HDMI OSD(IC731) correct
(like the one shown in the diagram) when the power is turned on?
T7311
PSCL
T7312
PSDA
Check item(42). Check the I2C communication line :
Check OSD (IC731) and CPU(IC751) patterns as well as soldering.
If there is no problem, go to the next step.
Checking the HDMI Rx.
Remove the damping resistor R7324/R7325
of IC731.
Is the "I2C" waveform correct?
The CPU(IC751) is faulty. Replace with a new
device.
Checking the reset waveform.
Check the I2C communication line.
Example of the waveform to be checked
Recheck from check item (3).
If it does not work, replace the PCB.
The OSD(IC731) is faulty.
Replace with a new device.
YES
Recheck from check item (3).
If it does not work, replace the PCB.
Check the reset circuit between CPU (IC751) and HDMI OSD(IC731).
If there is no problem, the HDMI OSD (IC731) is faulty.
Replace with a new device.
NOYES
*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 )
NO
YES
YES
NO
89
Caution in
servicing
Electrical Mechanical Repair Information Updating
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