No.52054
V-21BT8ENS AV-21BT8ENB
V-21BT8EPS AV-21BT8EPB
V-21BT8EES AV-21BT8EEB
V-21BT80EP
4
SAFETY PRECAUTIONS
1. The d esi gn of th is prod uct con ta in s sp ecial har d wa re , ma ny
circuits and components specially for safety purposes. For
con tinu ed prot ection , n o chan g es sh ou ld b e ma de to the o rig i nal
d esi gn un less a uth or ized in writi n g by th e ma nu fact ur er .
Rep lacem en t p ar ts m ust b e id ent ic al to thos e u sed in th e or igin al
ci rcu it s. Se r vic e sh ou ld be pe rf or me d b y q ua lifie d per so nn el
on ly.
2. Al te r ati on s of t he desig n or cir cuitr y of t he pr od ucts sh ould not be
made. Any design alterations or additions will void the
m anu fact ur er's w arr a nt y and w ill f ur th er r eli eve t he ma nu factu r er
of r esp onsi b ility for per so na l i njur y or p r op er ty d am ag e r esul t in g
th er efr om .
3. M an y e lectr ical an d m ech anica l p arts in th e pr od ucts ha ve
special safety-related characteristics. T hese characteristics are
oft en no t e viden t f r om visua l insp ection n or ca n t he pro tect io n
aff or de d by th em nece ssar il y b e ob tai n ed b y u sin g r ep lacem en t
com po ne nts ra ted f or hi g he r vo ltag e, w att ag e, etc. R ep lacemen t
p arts wh ic h ha ve th ese sp ecial s afet y ch aract er ist ics ar e
identified in the parts list of Servic e manual. El ec tric al
components having su ch features are identified by shading
on the sche matic s and by (!
!!
!) on the parts list in Service
manual. The us e of a sub stitu te rep la cem en t which do es n ot
h ave th e sam e saf ety ch ar act er ist ics as t he r eco mmen de d
r eplac em ent part sh own in th e p arts list of S er vice m an 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. T he
diff erenc e of th e GND is sh own by t he LI VE : (") side GND, the
ISO LATE D(NEUTRAL) : ( #) side GND an d EA RTH : ($) side
GND. Don't short between the LIVE side GND and
ISO LATE D(NEUTRAL) side GND or EARTH sid e GND and
n ever m ea sur e wit h a m ea sur ing a ppa r atus ( osci llo scop e etc.)
th e LI VE sid e GND an d IS OL ATED (NE UTR AL ) sid e GND or
EARTH side GND at th e 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 ti ng shou l d b e ch ecke d or adju ste d ( Se e
ADJUSTMENT OF B 1 POW E R SUPPL Y).
6. The hi gh vol ta ge app lie d t o th e pictu r e tu be mu st con for m wit h
th at sp eci fied in S ervi ce m an ual. E xcessive h igh vo lt ag e ca n
cau se an incr e ase in X- Ray em issi on , ar cing 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 evere arc in g occurs, r emove t he AC power
immed iate ly an d de ter mi ne th e ca use b y visua l i nsp ect io n
( in cor rect in stal lat i on, cr acke d or m elte d high vo lt age har n ess,
p oor so ld eri ng, et c.) . To maint ain the p rope r mi n imu m le vel of
sof t X- Ray em ission, c omp on en ts i n th e hi gh voltag e ci rcui tr y
incl ud ing t he pict ur e tu be must b e t he e xact r ep lacem e nts or
alte rn at ives ap prove d b y th e ma nuf act ur er of th e c om plet e
pr od uct.
7. Do n ot c hec k high volt ag e b y drawing an ar c. Use a high volt ag e
meter or a hig h v oltag e prob e wit h a VTV M. Dis charg e the
picture tube before attempting meter connection, by connecting
a cli p le ad to th e grou nd f ra me a nd c onn ecti n g th e oth er end of
the lead through a 10kΩ2W resi sto r to the an od e b utt on .
8. W hen se r vi ce is r equ ir e d, ob ser ve th e origi na l lea d dr ess. E xtr a
pr ec aut i on sh ou ld b e g i ve n t o assur e corr ect l ea d dress i n th e
hig h voltag e cir cuit a rea. W her e a s hor t ci rcuit h as occu rre d,
th ose co mp on ent s tha t indica te evide nce of ove r hea ti ng sho ul d
b e r e place d. A l wa ys u se th e ma nuf act ur er's r ep lacem en t
components.
9. Isolation Check
(Safety for Electrical Shock Hazard)
Af ter r e-ass emb lin g th e p r odu ct, al ways per f orm an i sol at io n
ch eck on the expo sed me tal p arts of t he cabin et ( a nte nn a
ter m ina ls, vid eo /au dio inpu t and ou tpu t t er min al s, Con tr ol kn obs,
metal cabinet, screwheads, earphone jack, control shafts, etc.)
to be su re th e p rodu ct is s af e t o o pe rate with ou t d an ger of
elect rical shoc k.
(1) Dielectric Strength Test
The i so l ati on be tw een the A C pr ima ry circu it an d all me tal p ar ts
exp ose d t o th e us er , p ar ticul arly an y e xp os ed met al p art h avi ng a
r etu rn 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 hstan d a vo lt ag e of 1 10 0V A C ( r .m. s.) t o an ap pl ianc e
r ate d up to 12 0V , an d 3 00 0V AC ( r .m. s.) to an ap pl ian ce r at ed
200V or more, for a period of one second.)
This method of test requires a t est equipment not generally found
in t he ser vic e tr ade.
(2) Leakage Current Check
Pl ug th e A C lin e c ord d irect l y in to th e A C ou tlet ( d o n ot use a li n e
isol ati o n tr ansf or m er du r in g this ch eck.). Usi n g a " Lea kag e
Cur rent Teste r", me asur e th e l ea kag e cu rr e nt f rom each exp osed
m etal p ar t of the ca bi ne t, p art icu lar ly any e xpos ed me tal p ar t
h aving a re turn path to t he ch assis , t o a kn own go od ea rt h
gr ou nd (w a ter pip e, e tc.) . An y leaka ge cur ren t m ust n ot e xceed
0.5mA AC (r.m.s.).
Howeve r, i n tr op ic al ar ea , th is mu st no t exce ed 0.2 mA AC
(r.m.s.).
"
""
"Alte rn ate Che ck Met hod
Pl ug th e A C lin e c ord d irect l y in to th e A C ou tlet ( d o n ot use a li n e
isol ati o n tr an sfor mer dur ing t hi s che ck.) . U se an AC vo lt me ter
h avi ng 1 00 0 oh ms pe r vol t or m ore sens it ivity in th e fo llow ing
m ann er. Con nec t a 1 50 0Ω10W res ist or par a lle le d b y a 0 .1 5µF
AC -type c apa cit or bet we en an expo sed met al pa rt a nd a kno wn
g ood e ar th gro un d ( wa ter pi pe , etc.) . Meas ur e th e A C vo lt ag e
acr oss th e r es ist or w ith th e AC vo ltm eter . M ove th e r esi stor
con nec ti on to e ach exp ose d me tal par t, p art icul arly a ny exp osed
m etal p ar t havi n g a retu rn pat h to t he ch assis, an d m easu r e th e
AC vol tag e ac ro ss the r es ist or . No w, re ver se th e plu g in th e AC
ou tl et and r e pe at eac h mea sur em en t. An y volt ag e me asu re d
must not exc eed 0.7 5V AC (r.m. s.). This c orresponds to 0.5mA
AC (r.m.s.).
However, in tropical area, this must n ot exceed 0.3V AC ( r.m. s.).
This corresponds to 0.2mA AC (r.m.s.).
0.15μF AC-T YPE
1500 Ω10W
GOODEARTH GROUND
PLACE THIS PROBE
ON E A CH EX PO SE D
ME T AL PA RT
ACVOLTMETER
(HAVING 1000 Ω/V,
OR MOR E SENSIT IVITY)
