Important Service Notes
1. X-ray Radiation RrecautionConnect at 1500 ohm 10 watt resistor, paralleled by a 0.15 mfd. AC type
capacitor, between a known good earth ground (water pipe, conduit etc.)
1) Excessive high voltage can produce potentially hazardous X-RAY RADIA-
and the exposed metallic parts, one at a time. Measure the AC voltage
TION. To avoid such hazards, the high voltage must not be above the spec-
across the combination of 1500 ohm resistor and 0.15 mfd capacitor. Volt-
ified limit. The nominal value of the high voltage of this receiver is
age measured must not exceed 0.3 volts RMS. This corresponds to 0.2 mill-
25.5kv(20?/21?) & 23.5kv(14?)at zero beam current (minimum brightness)
liamp. AC. Any value exceeding the limit constitutes a potential shock
under a 120V/220V AC power source. The high voltage must not, under any
hazard and must be corrected immediately.
circumstances, exceed 28kv(20?/21?) & 26kv(14?). Each time a receiver
requires servicing, the high voltage should be checked following the HIGH
VOLTAGE CHECK procedure on page 10 of this manual. It is recom-
AC VOLT METER
mended as a parts of the service record. It is important to use an accurate
and reliable high voltage meter.
2) This receiver is equipped with X-RADIATION PROTECTION circuit which
prevents the receiver from producing an excessively high voltage even if the
B+voltage increases abnormally. Each time the receiver is serviced, X-
RADIATION PROTECTION circuit must be checked to determine that the
0.15uF
circuit is properly functioning, following the X-RADIATION PROTECTION
1500 OHM
Place this probe
CIRCUIT CHECK procedure on page 6 of this manual.
on each exposed
Good earth ground
3) The only source of X-RAY RADIATION in this TV receiver is the picture tube.such as d watermetallic part.
pipe, conduit, etc.10WATT
For continued X-RAY RADIATION protection, the replacement tube must be
exactly the same type tube as specified in the parts list.
4) Some parts in this receiver have special safety-related characteristics for X-
3. Product Safety Notice
RAY RADIATION protection. For continued safety, parts replacement
should be undertaken only after referring to the PRODUCT SAFETYMany electrical and mechanical parts in this chassis have special safety-related
NOTICE below.characteristics. These characteristics are often passed unnoticed by a visual
inspection and the protection afforded by them cannot necessarily be obtained
2. Safety Precautionby using replacement components rated for higher voltage, wattage, etc.
Replacement parts which have these special safety characteristics are identi-
WARNING: Service should not be attempted by anyone unfamiliar with the
fied in this manual and its supplements; electrical components having such fea-
necessary precaution on this receiver. The following are the necessary precau-
tures are identified by shading on the schematic diagram and the parts list.
tion to be observed before servicing.
Before replacing any of these components, read the parts list in this manual
carefully. The use of substitute replacement parts which do not have the same
1) Since the chassis of this receiver has hazardous potential to ground when-
safety characteristics as specified in the parts list may create X-ray radiation or
ever the receiver is plugged in (floating chassis), an isolation transformer
other hazards.
must be used during servicing to avoid shock hazard.
2) Always discharge the picture tube anode to the CRT conductive coating the
4. Service Notes
picture tube. The picture tube is highly evacuated and if broken, glass frag-
ments will be violently expelled. Use shatterproof goggles and keep picture1) When replacing parts or circuit boards, clamp or bend the lead wires to termi-
tube away from the body while handling.nals before soldering.
3) When placing chassis in the cabinet, always be certain that all the protective2) When replacing a high wattage resistor (metal oxide film resistor) in the cir-
devices are put back in place, such as; nonmetallic control knobs, insulat-cuit board, keep the resistor min 1/2 inch away form circuit board.
ing covers, shields, isolation resistor-capacitor network, etc.3) Keep wires away from high voltage or high temperature components.
4) Before returning the set to the customer, always perform an AC leakage cur-
rent check on the exposed metallic parts of the cabinet, such as antennas,
terminals, screw-heads, metal overlays, control shafts etc. to be sure the set
DAEWOO ELECTRONICS CO., LTD.
is safe to operate without danger of electrical shock. Plug the AC line cordC.P.OBOX8003 SEOUL, KOREA
directly into a 120V AC outlet (do not use a line isolation transformer duringTel : 82-2-360-7798
Fax : 82-2-360-7877
this check). Use an AC voltmeter having 5000 ohms per volt or more sensi-
E-mail :
[email protected]
tivi-ty in the following manner.Printed in Apr. 2000
ACEC
