Marantz AV7703 Service Manual page 120

When the results of check item (61) are "78 or
(Detection of 5V is not OK.)
Check the +5V voltage. (Front HDMI Buffer)
Check item(63). Check the +5V voltage.
Does the HDMI Tx (IC431) test point indicate (5V)?
The test points are as follows.
106 pin
IC431
5V
YES
HDMI Tx (IC431) is faulty.
Replace with a new device.
Recheck from check item (5).
If it does not work, replace the PCB.
70"
NO
Check for a short circuit in the 5 V line, the
Front HDMI FFC, and the 5 V Switch (IC392).
If there is no problem, the HDMI Tx (IC431) or
the 5 V Switch (IC392) is faulty.
Replace with a new device.
When the results of check item (62) are
(Detection of DDC is not OK.)
Check the DDC Line. (Front HDMI Buffer)
Check item(64). Check the DDC line :
Are the "DDCSCK" and "DDCSDA" waveforms for
the HDMI Tx (IC431) signal correct (as shown in the
figure)?
The test points are as follows.
CN431
CN431
DDCSCK
DDCSDA
YES
HDMI Tx (IC431) is faulty.
Replace with a new device.
Recheck from check item (5).
If it does not work, replace the PCB.
120
"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 and
check the Front HDMI FFC.
If there is no problem, the Front HDMI
Buffer(IC101) is faulty.
Replace with a new device.