Daewoo DTQ-14N2FC Service Manual page 4

Product safety servicing guidelines for color
television receivers
CAUTION :
Do not attempt to modify this product in any
way. Unauthorized modifications will not only void the
warranty, but may lead to your being liable for any
resulting property damage or user injury.
Service work should be performed only after you are
thoroughly familiar with all of the following safety checks
and servicing guidelines. To do otherwise, increases the
risk of potential hazards and injury to the user.
SAFETY CHECKS
After the original service problem has been corrected, a
check should be made of the following:
SUBJECT : FIRE & SHOCK HAZARD
1. Be sure that all components are positioned in such a
way as to avoid possibility of adjacent component
shorts. This is especially important on those chassis
which are transported to and from the repair shop.
2. Never release a repair unless all protective devices
such as insulators, barriers, covers, shields, strain
reliefs, and other hardware have been reinstalled per
original design.
3. Soldering must be inspected to discover possible cold
solder joints, frayed leads, damaged insulation
(including A.C. cord), solder splashes or sharp solder
points. Be certain to remove all loose foreign particals.
4. Check for physical evidence of damage or deterioration
to parts and components, and replace if necessary
follow original layout, lead length and dress.
5. No leads or components should touch a receiving tube
or a resistor rated at 1 watt or more. Lead tension
around protruding metal surfaces must be avoided.
6. All critical components such as fuses, flameproof
resistors, capacitors, etc. must be replaced with exact
factory types. Do not use replacement components
other than those specified or make unrecommended
circuit modifications.
7. After re-assembly of the set always perform an A.C.
leakage test on all exposed metallic parts of the
cabinet, (the channel selector knob, antenna terminals,
handle and screws) to be sure the set is safe to operate
without danger of electrical shock. Do not use a line
isolation transformer during this test. Use an A.C.
voltmeter, having 5000 ohms per volt or more
sensitivity, in the following manner : connect a 1500
ohm 10 watt resistor, paralleled by a 15 mfd. 150V A.C.
type capacitor between a known good earth ground
9water pipe, conduit, etc.) and the exposed metalic
parts, one at a time. Measure the A.C. voltage across
the combination of 1500 ohm resistor and 0.15 MFD
capacitor. Reverse the A.C. plug and repeat A.C.
voltage measurements for each exposed metallic part.
Voltage measured must not exceed 0.75 volts R.M.S.
This corresponds to 0.5 milliamp A.C. Any value
exceeding this limit constitutes a potential shock hazard
and must be corrected immediately.
A.C. VOLTMETER
Good earth ground,
such as the water
pipe, conduit, etc.
GRAPHIC SYMBOLS :
The lightning flash with arrowhead symbol,
within an equilateral triangle, is intended to
alert the service personnel to the presence
of uninsulated dangerous voltage
may be of sufficienty magnitude to
constitute a risk of electric shock.
The exclamation point within an equilateral
triangle is intended to alert the service
personnel to the presence of important
safety information in service literature.
Fuse symbol is printed on pcb adjacent to
the fuse, with RISK OF FIRE REPLACE
FUSE AS MARKED . The symbol is
explained in the service manual with the
following wording or equivalent.
CAUTION : FOR CONTINUED PROTECTION AGAINST
FIRE HAZARD, REPLACE ONLY WITH SAME TYPE 4A,
125V FUSE and ATTENTION: AFIN D ASSU UNE
PROTECTION PERMANENTE CONTRE LES RISQUES
D INCENDIE, REMPLACER UNIQUEMENT PAR UN
FUSIBLE DE MEME TYPE ET DE 4A, 125V .
SUBJECT : X-RADIATION
1. Be sure procedures and instructions to all service
personnel cover the subject of X-rays in current T.V.
receivers is the picture tube. However, this tube does
not emit X-rays when the high voltage is at the factory
specified level. The proper value is given in the
applicable schematic. Operation at higher voltages may
cause a failure of the picture tube or high voltage
supply and, under certain circumstances, may produce
radiation in excess of desirable levels.
2. Only factory specified C.R.T. anode connectors must
be used. Degaussing shields also serve as X-ray shield
in color sets. Always re-install them.
3. It is essential that the serviceman has available an
accurate and reliable high voltage meter. The
calibration of the meter should be checked perio -
dically against a reference standard. Such as the one
available at your distributor.
4. When the high voltage circuitry is operating properly
there is no possibility of an X-radiation problem. Every
time a color chassis is serviced, the brightness should
be run up and down while monitoring the high voltage
4
0.15µF
• •
1500 OHM Place this probe
on each exposed
10WATT
metal part.
that