JVC HV-32D25EUW Service Manual page 4

HV-32D25EUW
HV-32D25EJW
1.1 HV-32D25EUW
(1) The design of this product contains special hardware,
many circuits and components specially for safety purpos-
es. For continued protection, no changes should be made
to the original design unless authorized in writing by the
manufacturer. Replacement parts must be identical to
those used in the original circuits. Service should be per-
formed by qualified personnel only.
(2) Alterations of the design or circuitry of the products should
not be made. Any design alterations or additions will void
the manufacturer's warranty and will further relieve the
manufacturer of responsibility for personal injury or prop-
erty damage resulting therefrom.
(3) Many electrical and mechanical parts in the products have
special safety-related characteristics. These characteris-
tics are often not evident from visual inspection nor can the
protection afforded by them necessarily be obtained by
using replacement components rated for higher voltage,
wattage, etc. Replacement parts which have these special
safety characteristics are identified in the parts list of Ser-
vice manual. Electrical components having such fea-
tures are identified by shading on the schematics and
by ( ) on the parts list in Service manual. The use of
a substitute replacement which does not have the same
safety characteristics as the recommended replacement
part shown in the parts list of Service manual may cause
shock, fire, or other hazards.
(4) Don't short between the LIVE side ground and ISO-
LATED (NEUTRAL) side ground or EARTH side
ground when repairing.
Some model's power circuit is partly different in the GND.
The difference of the GND is shown by the LIVE : (
GND, the ISOLATED (NEUTRAL) : (
EARTH : ( ) side GND.
Don't short between the LIVE side GND and ISOLATED
(NEUTRAL) side GND or EARTH side GND and never
measure the LIVE side GND and ISOLATED (NEUTRAL)
side GND or EARTH side GND at the same time with a
measuring apparatus (oscilloscope etc.).
If above note will not be kept, a fuse or any parts will be
broken.
(5) If any repair has been made to the chassis, it is recom-
mended that the B1 setting should be checked or adjusted
(See ADJUSTMENT OF B1 POWER SUPPLY).
(6) The high voltage applied to the picture tube must conform
with that specified in Service manual. Excessive high volt-
age can cause an increase in X-Ray emission, arcing and
possible component damage, therefore operation under
excessive high voltage conditions should be kept to a min-
imum, or should be prevented. If severe arcing occurs, re-
move the AC power immediately and determine the cause
by visual inspection (incorrect installation, cracked or melt-
ed high voltage harness, poor soldering, etc.). To maintain
the proper minimum level of soft X-Ray emission, compo-
nents in the high voltage circuitry including the picture tube
must be the exact replacements or alternatives approved
by the manufacturer of the complete product.
(7) Do not check high voltage by drawing an arc. Use a high
voltage meter or a high voltage probe with a VTVM. Dis-
charge the picture tube before attempting meter connec-
tion, by connecting a clip lead to the ground frame and
4
SECTION 1
SAFETY PRECAUTIONS
(8) When service is required, observe the original lead dress.
(9) Isolation Check
a) Dielectric Strength Test
b) Leakage Current Check
) side
) side GND and
connecting the other end of the lead through a 10k
resistor to the anode button.
Extra precaution should be given to assure correct lead
dress in the high voltage circuit area. Where a short circuit
has occurred, those components that indicate evidence of
overheating should be replaced.
Always use the manufacturer's replacement components.
(Safety for Electrical Shock Hazard)
After re-assembling the product, always perform an isola-
tion check on the exposed metal parts of the cabinet (an-
tenna terminals, video/ audio input and output terminals,
Control knobs, metal cabinet, screw heads, earphone
jack, control shafts, etc.) to be sure the product is safe to
operate without danger of electrical shock.
The isolation between the AC primary circuit and all metal
parts exposed to the user, particularly any exposed metal
part having a return path to the chassis should withstand
a voltage of 3000V AC (r.m.s.) for a period of one second.
(. . . . Withstand a voltage of 1100V AC (r.m.s.) to an ap-
pliance rated up to 120V, and 3000V AC (r.m.s.) to an ap-
pliance rated 200V or more, for a period of one second.)
This method of test requires a test equipment not general-
ly found in the service trade.
Plug the AC line cord directly into the AC outlet (do not use
a line isolation transformer during this check.). Using a
"Leakage Current Tester", measure the leakage current
from each exposed metal part of the cabinet, particularly
any exposed metal part having a return path to the chas-
sis, to a known good earth ground (water pipe, etc.). Any
leakage current must not exceed 0.5mA AC (r.m.s.).
However, in tropical area, this must not exceed 0.2mA AC
(r.m.s.).
Alternate Check Method
Plug the AC line cord directly into the AC outlet (do not
use a line isolation transformer during this check.). Use
an AC voltmeter having 1000 ohms per volt or more sen-
sitivity in the following manner. Connect a 1500 ohm
10W resistor paralleled by a 0.15µF AC-type capacitor
between an exposed metal part and a known good earth
ground (water pipe, etc.). Measure the AC voltage across
the resistor with the AC voltmeter. Move the resistor con-
nection to each exposed metal part, particularly any ex-
posed metal part having a return path to the chassis, and
measure the AC voltage across the resistor. Now, re-
verse the plug in the AC outlet and repeat each measure-
ment. Any voltage measured must not exceed 0.75V AC
(r.m.s.). This corresponds to 0.5mA AC (r.m.s.).
However, in tropical area, this must not exceed 0.3V AC
(r.m.s.). This corresponds to 0.2mA AC (r.m.s.).
0.15uF AC-TYPE
1500Ω 10W
GOOD EARTH GROUND
2W
AC VOLTMETER
(HAVING 1000Ω/V,
OR MORE SENSITIVITY)
PLACE THIS PROBE
ON EACH EXPOSED
METAL PART