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GB 4
2.
2. Safety & maintenance instructions, warnings and notes
2.1
Safety instructions for repairs
Safety regulations require that during a repair:
Safety components, indicated by the symbol ∆, should be
•
replaced by components identical to the original ones;
•
When replacing the CRT, safety goggles must be worn.
Safety regulations require that after a repair, the set must be
returned in its original condition. In particular attention should
be paid to the following points:
•
General repair instruction: as a strict precaution, we
advise you to resolder the solder joints, through which
the horizontal deflection current is flowing, in particular:
–
All pins of the line output transformer (LOT);
–
Fly-back capacitor(s);
–
S-correction capacitor(s);
–
Line output transistor;
–
Pins of the connector with wires to the deflection coil;
–
Other components through which the deflection
current flows.
Note: This resoldering is advised to prevent bad connections
due to metal fatigue in solder joints and is therefore only
necessary for television sets older than 2 years.
•
The wire trees and EHT cable should be routed correctly
and fixed with the mounted cable clamps.
•
The insulation of the mains lead should be checked for
external damage.
•
The mains lead strain relief should be checked for its
function in order to avoid touching the CRT, hot
components or heat sinks.
•
The electrical DC resistance between the mains plug and
the secondary side should be checked (only for sets
which have a mains isolated power supply). This check
can be done as follows:
–
Unplug the mains cord and connect a wire between
the two pins of the mains plug;
–
Set the mains switch to the 'ON' position (keep the
mains cord unplugged!);
–
Measure the resistance value between the pins of
the mains plug and the metal shielding of the tuner or
the aerial connection on the set. The reading should
be between 4.5 MΩ and 12 MΩ.
–
Switch off the TV and remove the wire between the
two pins of the mains plug.
•
The cabinet should be checked for defects to avoid
touching of any inner parts by the customer.
2.2
Maintenance instructions
It is recommended to have a maintenance inspection carried
out by a qualified service employee. The interval depends on
the usage conditions:
•
When the set is used under normal circumstances, for
example in a living room, the recommended interval is 3
to 5 years.
•
When the set is used in circumstances with higher dust,
grease or moisture levels, for example in a kitchen, the
recommended interval is 1 year.
•
The maintenance inspection contains the following
actions:
–
Execute the above-mentioned 'general repair
instruction'.
–
Clean the power supply and deflection circuitry on
the chassis.
–
Clean the picture tube panel and the neck of the
picture tube.
EM1A
Safety & maintenance instructions, warnings and notes
2.3
Warnings
•
In order to prevent damage to IC's and transistors, all
high-voltage flashovers must be avoided. In order to
prevent damage to the picture tube, the method shown in
Fig. 2-1 should be used to discharge the picture tube.
Use a high-voltage probe and a multimeter (position
VDC). Discharge until the meter reading is 0 V (after
approx. 30 s).
V
Figure 2-1
•
All IC's and many other semiconductors are susceptible
to electrostatic discharges (ESD). Careless handling
during repair can reduce life drastically. When repairing,
make sure that you are connected with the same
potential as the mass of the set by a wristband with
resistance. Keep components and tools also at this same
potential. Available ESD protection equipment:
–
Complete kit ESD3 (small table mat, wristband,
connection box, extension cable and earth cable)
4822 310 10671.
–
Wristband tester 4822 344 13999.
•
Together with the deflection unit and any multipole unit,
the used flat square picture tubes form an integrated unit.
The deflection and the multipole units are set optimally at
the factory. Adjustment of this unit during repair is
therefore not recommended.
•
Be careful during measurements in the high-voltage
section and on the picture tube.
•
Never replace modules or other components while the
unit is switched ON.
•
When making settings, use plastic rather than metal
tools. This will prevent any short circuits and the danger
of a circuit becoming unstable.
CL 26532098/042
140792
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