Marantz AV7703 Service Manual page 100

When the results of check item (13) are "NO"
(Detection of 5V is not OK)
Check the +5V voltage. (HDMI IN5 - 7)
Check item(15). Check the +5V voltage.
Does the test point near HDMI input terminal (JK391/JK392/JK393) indicate 5V?
JK393 JK392 JK391
5V 5V
5V
YES
HDMI Switcher1 (IC391) is faulty.
Replace with a new device.
Recheck from check item (3).
If it does not work, replace the PCB.
NO
Check for a short circuit in the 5 V line and the 5
V Switch IC (IC392).
If there is no problem, the HDMI Switcher1 (IC391)
or the 5 V Switch IC (IC392) is faulty
Replace with a new device.
When the results of check item (14) are
(Detection of DDC is not OK.)
Check the DDC line. (HDMI IN5 - 7)
Check item(16). Check the DDC line :
Are waveforms of "DDCSCK" and "DDCSDA" observed at the test point near the HDMI input
terminal(JK391/JK392/JK393)?
JK393 JK392 JK391
DDCSCK
DDCSDA
YES
HDMI Switcher1 (IC391) is faulty.
Replace with a new device.
Recheck from check item (3).
If it does not work, replace the PCB.
100
"00 or 04"
less than 100KHz
5V
5V
This diagram shows an example of the DDC commu-
nication waveform.
-The high level voltage is 5V.
-The frequency of the DDC CLK is 100 KHz or less.
Check at each test point.
NO
Check for a short circuit in the DDC line.
If there is no problem, the HDMI Switcher1 (IC391)
is faulty.
Replace with a new device.