Marantz SR5012 Service Manual page 106

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 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
NO
The CPU [U1018] is faulty.
Replace with a new device.
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