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FILE NO. 050-200127
SERVICE MANUAL
COLOUR TELEVISION
29VH14P
PRINTED IN U. K
Precautions
1. Precautions
Follow these safety, servicing and ESD precautions to prevent damage and protect against potential
hazards such as electrical shock and X-rays.
1-1 Safety Precautions
1. Be sure that all of the built-in protective
devices are replaced. Restore any missing (READING SHOULD
protective shields. LEAKAGE NOT BE ABOVE
DEVICE CURRENT 0.5mA)
UNDER TESTER
TEST
2. When reinstalling the chassis and its TEST ALL
assemblies, be sure to restore all protective EXPOSED METAL
SURFACES
devices, including: nonmetallic control knobs
3-WIRE CORD
and compartment covers.
ALSO TEST WITH
PLUG REVERSED
3. Make sure that there are no cabinet openings (USING AC ADAPTER EARTH
PLUG AS REQUIRED) GROUND
through which people--particularly
children--might insert fingers and contact
dangerous voltages. Such openings include
Fig. 1-1 AC Leakage Test
the spacing between the picture tube and the
cabinet mask, excessively wide cabinet
6. Antenna Cold Check:
ventilation slots, and improperly fitted back
With the unit's AC plug disconnected from the
covers.
AC source, connect an electrical jumper across
the two AC prongs. Connect one lead of the
If the measured resistance is less than 1.0
ohmmeter to an AC prong. Connect the other
megohm or greater than 5.2 megohms, an
lead to the coaxial connector.
abnormality exists that must be corrected
before the unit is returned to the customer.
7. X-ray Limits:
The picture tube is especially designed to
4. Leakage Current Hot Check (Figure 1-1):
prohibit X-ray emissions. To ensure continued
Warning: Do not use an isolation
X-ray protection, replace the picture tube only
transformer during this test. Use a leakage-
with one that is the same type as the original.
current tester or a metering system that
Carefully reinstall the picture tube shields and
complies with American National Standards
mounting hardware; these also provide X-ray
Institute (ANIS C101.1, Leakage Current for
protection.
Appliances), and Underwriters Laboratories
(UL Publication UL1410, 59.7).
8. High Voltage Limits:
High voltage must be measured each time
5. With the unit completely reassembled, plug
servicing is done on the B+, horizontal
the AC line cord directly into the power
deflection or high voltage circuits.
outlet. With the unit's AC switch first in the
Correct operation of the X-ray protection
ON position and then OFF, measure the
circuits must be reconfirmed whenever they
current between a known earth ground (metal
are serviced.
water pipe, conduit, etc.) and all exposed
(X-ray protection circuits also may be called
metal parts, including: antennas, handle
"horizontal disable" or "hold-down".)
brackets, metal cabinets, screwheads and
control shafts. The current measured should
Heed the high voltage limits. These include
not exceed 0.5 milliamp. Reverse the power-
the X