No.52024
V-21F
V-21FR3
V-21FMG3B
3
SAFETY PRECAUTIONS
1. The d esign of th is pr od uct con tains sp ecial hard ware, ma ny
circuit s and components specially for safety purposes. For
con tinu ed prot ection , no chan g es sh ou ld b e ma de to the o rig inal
d esign unless a uth or ized in writin g by the ma nu fact ur er .
Replacem en t p ar ts m ust b e id ent ic al to thos e u sed in th e origin al
circu it s. S ervice sho uld b e p erformed by qu alif ied p ers onnel
on ly.
2. Alte ration s of t he design or cir cuitry of t he pr od ucts sh ould not be
made. Any design alterations or additions will void the
manu fact urer's warra nt y and will f urth er relieve t he manu factu rer
of r esp onsibility for per so na l injury or p rop erty d amag e result ing
th er efrom.
3. M an y e lectr ical an d m echanica l parts in th e pr od ucts have
special safety-related characteristics. T hese characteristics are
oft en no t e viden t f rom visua l insp ection n or ca n t he pro tect ion
aff orde d by th em nece ssarily be ob tain ed b y u sing rep lacemen t
compo ne nts ra ted f or hig he r voltage, watt ag e, etc. Rep lacemen t
p arts wh ic h ha ve th ese sp ecial s afet y ch ar act erist ics ar e
identified in the parts list of Servic e manual. El ec trical
components having su ch features are identified by shading
on the sche matics and by (!
!!
! ) on the parts list in Service
manual. The us e of a sub stitu te rep la cemen t which do es n ot
h ave th e same saf ety ch ar act er ist ics as t he reco mmen de d
replac ement part shown in the p arts list of S er vice man ual m ay
cause shock, fire, or other hazards.
4. Do n't shor t between the LIVE side ground and ISOL ATED
(NEUTRAL) side ground or EARTH side ground when
repairing.
Some model's power circuit is partly different in the GND. The
diff erenc e of the G ND is sho wn b y th e LIV E : ( ") side GND, the
ISO LATE D(NEUTRAL) : (#) side G ND and EARTH : ($) side
GND. Do n't shor t b et ween the LIV E sid e GND an d
ISO LATE D(NEUTRAL) side GND or EARTH side GND and
n ever mea sure wit h a m ea sur ing a ppa ratus (oscillo scop e etc.)
th e LI VE sid e GND an d IS OLA TED(NE UTRAL ) side G ND or
EARTH sid e GND at the s ame time.
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 recommended
th at t he B1 set ting shou ld b e ch ecke d or adju ste d (See
ADJUSTMENT OF B1 POW E R SUPPL Y).
6. The high volta ge app lie d t o th e pictu re tube must con for m wit h
th at sp ecified in S ervice man ual. E xcessive h igh vo lt ag e ca n
cau se an incre ase in X-Ray emission , arcing an d possib le
component damage, therefore operation under excessive high
voltage conditions should be kept to a minimum, or should be
preve nt ed. If s ever e arc ing occurs, remove t he AC power
immed iately an d de termine th e ca use b y visua l insp ect ion
(in corr ect installat ion, cracke d or melted high vo lt age harn ess,
p oor so ld ering, et c.). To maint ain the p rope r min imu m le vel of
sof t X-Ray emission, c omp on en ts in the high voltag e circuitry
including t he pict ure tu be must b e t he e xact rep laceme nts or
alte rnat ives ap prove d b y th e ma nuf act urer of th e c omplet e
prod uct.
7. Do n ot c hec k high volt ag e b y dr awing an arc. Use a high volt ag e
meter or a hig h v oltage prob e wit h a V TVM. Discha rg e th e
picture tube before attempting meter connection, by connecting
a clip le ad to the grou nd f rame a nd c onn ecting th e oth er end of
the lead through a 10kΩ 2W resisto r to the an od e b utt on .
8. When se r vice is r equired, ob serve the or igina l lea d dress. E xtra
prec aut ion sh ould b e g ive n t o assure corr ect lea d dress in th e
high voltag e circuit a rea. W here a s hort circuit h as occu rre d,
th ose comp on ent s that indicate evidence of ove rhea ting sho uld
b e re place d. A lways u se th e ma nuf act urer's rep lacemen t
components.
9. Isolation Check
(Safety for Electrical Shock Hazard)
Af ter re-ass emb lin g the p r odu ct, always perf orm an isolat ion
ch eck on the expo sed metal p ar ts of t he cabin et ( a nte nn a
ter minals, video /au dio inpu t and ou tpu t t ermin als, Con trol kn obs,
metal cabin et, scr ewhe ad s, ea r ph one jack, con tr ol shaf ts, etc.)
to be su re th e p r odu ct is s af e t o o pe rate withou t d an ger of
elect rical shoc k.
(1) Dielectric Strength Test
The iso lation be tween the A C prima ry circu it an d all metal p arts
exp ose d t o th e us er, p articularly an y exp os ed met al part h aving a
return p ath to t he chass is sho uld withs tan d a volt age of 3 000 V
AC (r.m.s.) for a period of one second.
(. . . . W it hstand a vo lt ag e of 1 10 0V A C ( r .m. s.) t o an ap plianc e
rated up to 12 0V , an d 3 00 0V AC ( r .m. s.) to an ap plian ce r at ed
200V or more, for a period of one second.)
This method of test requires a t est equipment n ot generally found
in t he servic e trad e.
(2) Leakage Current Check
Plug th e A C lin e c ord d irect ly into th e A C ou tlet (d o n ot use a lin e
isolatio n tr ansf or m er du ring this ch eck.) . Usin g a " Lea kag e
Current Tester", me asure th e lea kag e cu rre nt f rom each exp osed
metal p art of the cabine t, p art icu larly any e xpos ed metal p ar t
h aving a re turn pa th to t he ch assis , t o a kn own go od ea rt h
grou nd (wa ter pip e, e tc.) . Any leaka ge curr en t must not e xceed
0.5mA AC (r.m.s.).
However, in tropic al ar ea , th is must no t exce ed 0.2 mA AC
(r.m.s.).
"
""
" Alte rnate Che ck Met hod
Plug th e A C lin e c ord d irect ly into th e A C ou tlet (d o n ot use a lin e
isolatio n tr an sfor m er during t his check.) . Use an AC vo lt me ter
h aving 100 0 oh ms per volt or m or e sens it ivity in th e fo llowing
mann er. Con nec t a 1 500Ω 10W res ist or para lle le d b y a 0 .1 5µF
AC-type c apa cit or bet ween an expo sed met al pa rt a nd a kno wn
g ood ear th gro un d (water pipe , etc.). Meas ure th e A C vo lt ag e
across th e res ist or with the AC vo ltmeter. Move th e resistor
con nec tion to e ach exp ose d metal part, p art icular ly a ny exp osed
metal p art havin g a r etu rn pat h to t he ch assis, an d m easu re th e
AC voltage ac ro ss the res ist or. No w, re verse th e plu g in th e AC
ou tlet and re pe at eac h mea suremen t. Any volt ag e measu re d
must not exc eed 0.75V AC (r.m.s.). This c orresponds to 0 .5mA
AC (r.m.s.).
However, in tropica l are a, this must not exceed 0.3V AC ( r.m. s.).
This corresponds to 0.2mA AC (r.m.s.).
0.15μF AC-T YPE
1500 Ω 10W
GOOD EARTH GROUND
PLACE THIS PROBE
ON E A CH EX PO SE D
ME T AL PA R T
AC VOLTMETER
(HAVING 1000 Ω/V,
OR MORE SENSITIVITY)
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