IMPORTANT SERVICE NOTES
1. X-RAY RADIATION PRECAUTIONtion transformer during this check). Use an AC
voltmeter having 5000 ohms per volt or more sensitivi-
1) Excessive high voltage can produce potentially
ty in the following manner.
hazardous X-RAY RADIATION. To avoid such
hazards, the high voltage must not be above the
Connect at 1500 ohm 10 watt resistor, paralleled by a
specified limit. The nominal value of the high voltage
0.15 mfd. AC type capacitor, between a known good
of this receiver is 24.4kv at zero beam current
earth ground (water pipe, conduit etc.) and the
(minimum brightness) under a 120V AC power source.
The high voltage must not, under any circumstances,exposed metallic parts, one at a time. Measure the AC
exceed 27kv (28.5kw). Each time a receiver requiresvoltage across the combination of 1500 ohm resistor
and 0.15 mfd capacitor. Voltage measured must not
servicing, the high voltage should be checked following
exceed 0.3 volts RMS. This corresponds to 0.2
the HIGH VOLTAGE CHECK procedure on page 6 of
millliamp. AC. Any value exceeding the limit constitutes
this manual. It is recommended as a parts of the
a potential shock hazard and must be corrected
service record. It is important to use an accurate and
immediately.
reliable high voltage meter.
2) This receiver is equipped with X-RADIATION
AC VOLT METER
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 circuit is
properly functioning, following the X-RADIATION
PROTECTION CIRCUIT CHECK procedure on page 6
of this manual.0.15MFD
3) The only source of X-RAY RADIATION in this TV
receiver is the picture tube. For continued X-RAY1500 ohmPlace this probe
10watton each exposed
RADIATION protection, the replacement tube must beGood earth ground
metallic part.
such as d water
exactly the same type tube as specified in the parts list.
pipe, conduit, etc.
4) Some parts in this receiver have special safety-related
characteristics for X-RAY RADIATION protection. For
continued safety, parts replacement should be3. PRODUCT SAFETY NOTICE
undertaken only after referring to the PRODUCT
Many electrical and mechanical parts in this chassis have
SAFETY NOTICE below.
special safety-related characteristics. These
characteristics are often passed unnoticed by a visual
inspection and the protection afforded by them cannot
2. SAFETY PRECAUTION
necessarily be obtained by using replacement
WARNING: Service should not be attempted by anyone
components rated for higher voltage, wattage, etc.
unfamiliar with the necessary precaution on this receiver.
Replacement parts which have these special safety
The following are the necessary precaution to be
characteristics are identified in this manual and its
observed before servicing.
supplements; electrical components having such features
1) Since the chassis of this receiver has hazardousare identified by shading on the schematic diagram and
potential to ground whenever the receiver is plugged inthe parts list.
(floating chassis), an isolation transformer must beBefore replacing any of these components, read the parts
used during servicing to avoid shock hazard.list in this manual carefully. The use of substitute
replacement parts which do not have the same safety
2) Always discharge the picture tube anode to the CRT
characteristics as specified in the parts list may create X-
conductive coating the picture tube. The picture tube is
ray radiation or other hazards.
highly evacuated and if broken, glass fragments will be
violently expelled. Use shatterproof goggles and keep
4. SERVICE NOTES
picture tube away from the body while handling.
1) When replacing parts or circuit boards, clamp or bend
3) When placing chassis in the cabinet, always be certain
the lead wires to terminals before soldering.
that all the protective devices are put back in place,
such as; nonmetallic control knobs, insulating covers,2) When replacing a high wattage resistor (metal oxide
shields, isolation resistor-capacitor network, etc.film resistor) in the circuit board, keep the resistor min
1/2 inch away form circuit board.
4) Before returning the set to the customer, always
3) Keep wires away from high voltage or high
perform an AC leakage current check on the exposed
temperature components.
metallic parts of the cabinet, such as antennas,
terminals, screw-heads, metal overlays, control shafts
etc. to be sure the set is safe to operate without
danger of electrical shock. Plug the AC line cord
directly into a 120V AC outlet (do not use a line isola-
Minimum brightness
8 |
ACEC
