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5.5
The Blinking LED Procedure
Via this procedure, you can make the contents of the error
buffer visible via the front LED. This is especially useful when
there is no picture.
Go into the SDAM menu with one of the following methods:
1. '062596 M' on a System 7 remote control (the RC-
transmitter RG4172BK).
2. Short circuit wires 9631 and 9641 on the mono carrier and
apply AC power. Then press the power button (remove the
short circuit after start-up).
As soon as you are in SDAM the blinking LED procedure will
start.
Error-codes are shown as follows:
1. n short blinks (the number of n indicates the error code
number.),
2. a pause of 1.5 s,
3. n short blinks (for the next error),
4. when all the error-codes are displayed, the sequence
finishes with a LED blink of 3 s,
5. the sequence starts again.
Example of error buffer: 12 9 6 0 0
After entering SDAM:
1. 12 short blinks followed by a pause of 1.5 s,
2. 9 short blinks followed by a pause of 1.5 s,
3. 6 short blinks followed by a pause of 1.5 s,
4. 1 long blink of 3 s to finish the sequence,
5. the sequence starts again.
5.6
Protections
If a fault situation is detected an error code will be generated
and if necessary, the set will be put in the protection mode.
Blinking of the red LED at a frequency of 3 Hz indicates the
protection mode. In some error cases, the microprocessor
does not put the set in the protection mode. The error codes of
the error buffer can be read via the service menu (SDAM) or the
blinking LED procedure.
To get a quick diagnosis the chassis has two service modes
implemented:
•
The Customer Service Mode (CSM).
•
The Service Default Alignment Mode (SDAM). Start-up of
the set in a predefined way and adjustment of the set via a
menu and with the help of test patterns.
5.7
Repair Tips
Below some failure symptoms are given, followed by a repair
tip.
•
Set is dead and makes hiccuping sound
'MainSupply' is available. Hiccuping stops when de-
soldering L5561, meaning that problem is in the
'MainSupply' line. No output voltages at LOT, no horizontal
deflection. Reason: line transistor TS7460 is defective.
•
Set is dead, and makes no sound
Check power supply IC7520. Result: voltage at pins 1, 3, 4,
5 and 6 are about 180 V and pin 8 is 0 V. The reason why
the voltage on these pins is so high is because the output
driver (pin 6) has an open load. That is why MOSFET
TS7521 is not able to switch. Reason: feedback resistor
3523 is defective.Caution: be careful measuring on the
gate of TS7521; circuitry is very high ohmic and can easily
be damaged! (first connect measuring equipment to
ground, then to the gate).
•
Set is in hiccup mode and shuts down after 8 s.
Blinking LED (set in SDAM mode) indicates error 5. As it
is unlikely that P 'POR' and '+8V protection' happen at the
same time, measure the '+8V'. If this voltage is missing,
check transistor TS7480.
Service Modes, Error Codes and Fault Finding
L01H.2E
•
Set is non-stop in hiccup mode
Set is in over current mode; check the secondary sensing
(opto coupler 7515) and the 'MainSupply' voltage. Signal
'Stdby_con' must be logic low under normal operation
conditions and goes to high (3.3 V) under standby and fault
conditions.
•
Set turns on, but without picture and sound
The screen shows snow, but OSD and other menus are
okay. Blinking LED procedure indicates error 11, so
problem is expected in the tuner (pos. 1000). Check
presence of supply voltages. As 'Vlotaux+5V' at pin 5 and
7 are okay, 'VT_supply' at pin 9 is missing. Conclusion:
resistor 3460 is defective.
•
Set turns on, but with a half screen at the bottom.
Sound is okay
Blinking LED (set in SDAM mode) indicates error 3. Check
'Vlotaux+13V' and '+50V'. If they are okay, problem is
expected in the vertical amplifier IC7471. Measure with a
scope the waveform on pin 17 of the UOC. Measure also
at pin 1 of IC7471. If here the signal is missing, a defective
resistor R3244 causes the problem
5.
EN 11
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