Denon AVR-X3300W Service Manual page 109

Checking the reset waveform.
Check item(66). Checking the reset :
Check the CPU.
Is the waveform of the TP near the GUI (U1026) correct (like the one
shown in the diagram) when the power is turned on?
RESET
U1026
YES NO
Check the reset circuit between CPU (U1018) and GUI (U1026).
If there is no problem, the GUI (U1026) is faulty.
Replace with a new device.
Recheck from check item (1).
If it does not work, replace the PCB.
Check the I2C communication line.
Check item(67).
Check the CPU.
10ms
Is the waveform of the TP near the GUI(U1026) correct (like the one
shown in the diagram) when the power is turned on?
10ms 10ms
Example of the waveform to be checked
YES
The GUI (U1026) is faulty.
Replace with a new device.
Recheck from
If it does not work, replace the PCB.
109
YES
Check the I2C communication line :
A_DA
A_CK
U1026
NO
Check item(68). Check the I2C communication line :
Check GUI (U1026), HDMI Decoder (U1055) and CPU(U1018) patterns as well as soldering.
If there is no problem, go to the next step.
Check the HDMI Decoder.
Remove the damping resistor (R2142) of
HDMI Decoder (U1055).
Is the "I2C" waveform correct?
YES
HDMI Decoder (U1055) is faulty.
Replace with a new device.
check item (1).
*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 )
The GUI (U1026) is faulty.
NO
Replace with a new device.