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When the results of check item (3-17.1.) are
"78 or
(Detection of 5V is not OK.)
Check the +5V voltage. (HDMI DDC Buffer)
Check item(3-17.3.).
Check the +5V voltage.
Does the HDMI Tx [U3401] test point indicate (5V)?
The test points are as follows.
U3401
106 pin
YES
HDMI Tx [U3401] is faulty.
Replace with a new device.
Recheck from
check item (3.4.)
If it does not work, replace the PCB.
70"
NO
Check for a short circuit in the 5V line, the
Front HDMI FFC, and the 5V Switch [U2400].
If there is no problem, the HDMI Tx [U3401] or
the 5V Switch [U2400] is faulty.
Replace with a new device.
When the results of check item (3-17.2.) are
(Detection of DDC is not OK.)
Check the DDC Line. (HDMI DDC Buffer)
Check item(3-17.4.).
Check the DDC line :
Are the "DDCSCK" and "DDCSDA" waveforms for
the HDMI Tx [U3401] signal correct (as shown in the
figure)?
The test points are as follows.
N3403
F-HDMI
DDCSCK
DDCSDA
YES
HDMI Tx [U3401] is faulty.
Replace with a new device.
Recheck from
check item (3.4.)
If it does not work, replace the PCB.
137
"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 100kHz or less.
Check at each test point.
Voltage scale : 2.0V/div
Time scale : 40us/div
NO
Check for a short circuit in the DDC line and
check the Front HDMI FFC.
If there is no problem, the HDMI DDC Buffer
[U5501] is faulty.
Replace with a new device.
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