When the results of check item (3-17.1.) are "
78 or 70
"
(Detection of 5V is not OK.)
When the results of check item (3-17.2.) are "
00 or 04
"
(Detection of DDC is not OK.)
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
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
Check the +5V voltage. (HDMI DDC Buffer)
Check the DDC Line. (HDMI DDC Buffer)
HDMI Tx [
U3401
] is faulty.
Replace with a new device.
Recheck from
check item (3.4.)
If it does not work, replace the PCB.
Recheck from
check item (3.4.)
If it does not work, replace the PCB.
HDMI Tx [
U3401
] is faulty.
Replace with a new device.
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.
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.
YES
YES
NO
NO
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
Before Servicing
This Unit
Electrical
Mechanical
Repair Information
Updating
137
