Service Modes, Error Codes, and Fault Finding
EN 14
LC4.6E AA
5.
5.7
Fault Finding and Repair Tips
Notes:
•
It is assumed that the components are mounted correctly
with correct values and no bad solder joints.
•
Before any fault finding actions, check if the correct options
are set.
5.7.1
NVM Editor
In some cases, it can be handy if one directly can change the
NVM contents. This can be done with the “NVM Editor” in SAM
mode. With this option, single bytes can be changed.
Table 5-3 NVM editor overview
5.7.2
Load default NVM values
In case a blank NVM is placed or when the NVM content is
corrupted, default values can be downloaded into the NVM.
After the default values are downloaded it will be possible to
start up and to start aligning the TV set. This is no longer
initiated automatically; to initiate the download the following
action has to be performed:
1.
Switch “off” the TV set via the AC Power switch.
2.
Short circuit the SDM jumpers (keep short-circuited).
3.
Press P+ or Ch+ on the local keyboard (and keep it
pressed).
4.
Switch on the TV set via the AC Power switch.
5.
When the set has started, the P+/Ch+ button can be
released and the short circuit of the SDM jumpers can be
removed.
6.
The red LED will be on continuously to indicate that the
download is initiated (normally when SDM is activated the
red LED will start with the Blinking LED sequence).
7.
Wait +/- 30 s (time needed to download default values to
the NVM).
5.7.3
Tuner and IF
No Picture in RF mode
1.
Check whether picture is present in AV. If not, go to Video
processing troubleshooting section.
2.
If present, check that the Option settings are correct.
3.
Check that all supply voltages are present.
4.
Check if I
2
C lines are working correctly (3.3V).
5.
Manually store a known channel and check if there is IF
output at Tuner pin 11.
6.
Feed in 105 dBuV at Tuner pin 11 and check whether there
is RGB output from Video Processing IC. If yes, Tuner may
be defect. Replace Tuner.
Required system is not selected correctly
1.
Check whether a Service jumper (#4022, 0805 size) is
present. If yes, remove it.
5.7.4
Video Processing
No power
1.
Check +12 V and 3V3 at position 1910.
2.
If no supply, check the connector 1910.
3.
If it is correct, check the power supply board.
Power supply is correct but no green LED
1.
Check if connectors 1005 and 1601 are properly inserted.
2.
If yes, check if the 3V3 is present.
No picture display
1.
Check the RGB signal.
2.
If it is present, check 3-IC7016 (NE555).
3.
If it has output, the problem is in SCALER part.
4.
Otherwise, check H-out on pin 2 of NE555. If the input
signal of pin 2 is present, but no output, the IC is defect.
Note:
•
If the H-out (pin 67) doesn’t have signal or the level is low,
check the output of NE555 (pin 3) during start up.
•
If the H-out (pin 67) has a signal (or has a signal for a very
short time), change IC7016 (NE555).
No TV but PC is present
1.
Check if HSYNC and VSYNC are present at pin 3 of 7017
and 7015.
2.
If they are present, check RGB output.
3.
If there is no RGB output, the IC TDA120xx can be defect.
5.7.5
Power Supply
This power supply contains two fuses. One is near the AC
Power (or mains) inlet connector 1308 and the other is near
connector 1307.
1.
Check with power supply in “off” state by means of ohmic
measurement.
2.
Fuse 1400 may open in case of severe lightning strikes
and/or failures in the power supply.
3.
Fuses 1401 may open in case of a problem with the Stand-
by Supply. Replacement of the fuse is needed, but not
before the cause of the overload conditions is resolved.
Hex
Dec
Description
.ADR
0x000A
10
Existing value
.VAL
0x0000
0
New value
.Store
Store?