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COLOR MONITOR
PN15VT / VO
PN15HT / HO
SERVICE Manual
COLOR MONITOR CONTENTS
1. Precautions
2. Product Specifications
3. Disassembly & Reassembly
4. Alignment & Adjustments
5. Troubleshooting
6. Exploded View & Parts List
PN15VT/HT
7. Electrical Parts List
8. Block Diagram
9. Wiring Diagram
10. Schematic Diagrams
PN15VO/HO
1 Precautions
1-1 Safety Precautions
WARNINGS 3. Leakage Current Hot Check (Figure 1-1):
1. For continued safety, do not attempt to modify the WARNING: Do not use an isolation transformer during
circuit board. this test.
2. Disconnect the AC power before servicing. Use a leakage current tester or a metering system
3. When the chassis is operating, semiconductor that complies with American National Standards
heatsinks are potential shock hazards. Institute (ANSI C101.1, Leakage Current for
Appliances), and Underwriters Laboratories (UL
1-1-1 Servicing the High Voltage and CRT : Publication UL1410, 59.7).
WARNING:A high voltage adjusted to the wrong 4. With the unit completely reassembled, plug the AC
value may cause excessive X-ray line cord directly into a 120V AC outlet. With the
emissions. unit's AC switch first in the ON position and then
1. When servicing the high voltage system, remove OFF, measure the current between a known earth
the static charge by connecting a 10 kohm resistor ground (metal water pipe, conduit, etc.) and all
in series with an insulated wire (such as a test exposed metal parts, including: metal cabinets,
probe) between the chassis and the anode lead. screwheads and control shafts. The current
measured should not exceed 0.5 milliamp. Reverse
2. When troubleshooting a monitor with excessively the power-plug prongs in the AC outlet and repeat
HV, avoid being unnecessarily close to the monitor. the test.
Do not operate the monitor for longer than is
necessary to locate the cause of excessive voltage. (READING SHOULD
NOT BE ABOVE 0.5mA)
3. High voltage should always be kept at the rated
value, no higher. Only when high voltage is
LEAKAGE
excessive are X-rays capable of penetrating the shell DEVICE
UNDER
CURRENT
TESTER
of the CRT, including the lead in glass material. TEST
TEST ALL
Operation at high voltages may also cause failure of EXPOSED METAL
SURFACES
the CRT or high voltage circuitry.
4. When the HV regulator is operating properly, there 2-WIRE CORD
is no possibility of an X-ray problem. Make sure the
HV does not exceed its specified value and that it is
ALSO TEST WITH
regulating correctly. PLUG REVERSED
(USING AC ADAPTER
PLUG AS REQUIRED)
5. The CRT is especially designed to prohibit EARTH
GROUND
X-ray emissions. To ensure continued X-ray
protection, replace the CRT only with one that is Figure 1-1. Leakage Current Test Circuit
the same or equivalent type as the original.
6. Handle the CRT only when wearing shatterproof
1-1-3 Product Safety Notices
goggles and after completely discharging the high Some electrical and mechanical parts have special
voltage anode. safety-related characteristics which are often not
7. Do not lift the CRT by the neck. evident from visual inspection. The protection they give
may not be obtained by replacing them with
1-1-2 Fire and Shock Hazard : components rated for higher voltage, wattage, etc. Parts
that have special safety characteristics are identified by
Before returning the monitor to the user, perform the
! on schematics and parts lists. A substitute
following safety checks:
replacement that does not have the same safety
1. Inspect each lead dress to make certain that the characteristics as the recommended replacement part
leads are not pinched or that hardware is not might create shock, fire and / or other hazards. Product
lodged between the chassis and other metal parts in safety is under review continuously and new
the monitor. instructions are issued whenever appropriate.
2. Inspect all protective devices such as nonmetallic Components identified by on schematics and parts
control knobs, insulating materials, cabinet backs, lists must be sealed by a soldering iron after
adjustment and compartment covers or shields, replacement and adjustment.
isolation resistor-capacitor networks, mechanical
insulators, etc.
PN15VT/VO 1-1
PN15HT/HO
1 Precautions
1-2 Servicing Precautions
WARNING1: First read the "Safety Precautions" section of this manual. If unforeseen circumstances
create conflict between the servicing precautions and safety precautions, always
follow the safety precautions.
WARNING2: A high voltage adjusted to the wrong value may cause excessive X-ray emissions.
WARNING3: An electrolytic capacitor installed with the wrong polarity might explode.
1. Servicing precautions are printed on the cabinet, 5. Check the insulation between the blades of the AC
and should be followed closely. plug and accessible conductive parts (examples:
2. Always unplug the unit's AC power cord from the metal panels, input terminals and earphone jacks).
AC power source before attempting to: (a) remove 6. Insulation Checking Procedure: Disconnect the
or reinstall any component or assembly, (b) power cord from the AC source and turn the power
disconnect PCB plugs or connectors, (c) connect all switch ON. Connect an insulation resistance meter
test components in parallel with an electrolytic (500 V) to the blades of the AC plug.
capacitor. The insulation resistance between each blade of the
3. Some components are raised above the printed AC plug and accessible conductive parts (see
circuit board for safety. An insulation tube or tape above) should be greater than 1 megohm.
is sometimes used. The internal wiring is 7. Never defeat any of the +B voltage interlocks. Do
sometimes clamped to prevent contact with not apply AC power to the unit (or any of its
thermally hot components. Reinstall all such assemblies) unless all solid-state heat sinks are
elements to their original position. correctly installed.
4. After servicing, always check that the screws, 8. Always connect a test instrument's ground lead to
components and wiring have been correctly the instrument chassis ground before connecting the
reinstalled. Make sure that the area around the positive lead; always remove the instrument's
serviced part has not been damaged. ground lead last.
1-3 Electrostatically Sensitive Devices (ESD) Precautions
Some semiconductor (solid state) devices can be easily damaged by static electricity. Such components are commonly
called Electrostatically Sensitive Devices (ESD). Examples of typical ESD devices are integrated circuits and some field-
effect transistors. The following techniques will reduce the incidence of component damage caused by static electricity.
1. Immediately before handling any semiconductor 6. Do not remove a replacement ESD from its
components or assemblies, drain the electrostatic protective package until you are ready to install it.
charge from your body by touching a known earth Most replacement ESDs are packaged with leads
ground. Alternatively, wear a discharging wrist- that are electrically shorted together by conductive
strap device. To avoid a shock hazard, be sure to foam, aluminum foil or other conductive materials.
remove the wrist strap before applying power to 7. Immediately before removing the protective
the monitor. material from the leads of a replacement ESD,
2. After removing an ESD-equipped assembly, place it touch the protective material to the chassis or
on a conductive surface such as aluminum foil to circuit assembly into which the device will be
prevent accumulation of an electrostatic charge. installed.
3. Do not use freon-propelled chemicals. These can Caution: Be sure no power is applied to the
generate electrical charges sufficient to damage chassis or circuit and observe all
ESDs. other safety precautions.
4. Use only a grounded-tip soldering iron to solder or
8. Minimize body motions when handling
desolder ESDs.
unpackaged replacement ESDs. Motions such as
5. Use only an anti-static solder removal device. Some brushing clothes together, or lifting your foot from
solder removal devices not classified as "anti-static" a carpeted floor can generate enough static
can generate electrical charges sufficient to damage electricity to damage an ESD.
ESDs.
9. Indicates ESDs on the Schematic Diagram in
this manual.
1-2 PN15VT/VO
PN15HT/HO
2 Product Specifications
2-1 Specifications
Description
Item
PN15VT/VO PV15HT/HO
Picture Tube: 15-Inch (38 cm): 13.8-inch (35 cm) viewable,
Full-square flat-face tube, 90