Denon AVR-X2400H Service Manual page 101

Check the SPI communication line.
YES
Check item(33). Check the SPI communication line :
Check the CPU.
Is the "SPI" waveform of the TP near the DSP [U1073] correct (like
the one shown in the diagram) when the power is turned on?
3 pin CLK
4 pin MOSI
6 pin CS
5 pin MISO
U1073
YES NO
Check item(34). Check the SPI communication line :
Check DSP [U1073] and CPU [U1018] patterns as well as soldering.
If there is no problem, go to the next step.
The DSP [U1073] 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
timing.)
Points for checking waveforms
- Crest value (3.3 V normally)
- Signal change
- CLOCK frequency (about 6 MHz)
Voltage scale：2.0V/div
Time scale：2us/div
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