No.51945
V32H20EUS
V28H20EUS
V28H20EUB
4
SAFETY PRECAUTIONS
1. The d esi gn of th is pr od uct con ta in s sp eci al 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 l ess 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 i n th e or igin al
ci rcu it s. S er vice sho ul d b e p erfor med by qu alif ied p ers on nel
on ly.
2. Al te r ati on s of t he desig n or ci rcui tr y of t he pr od ucts sh oul d not be
made. Any design alterations or additions will void the
m anu fact ur er's w arr a nt y and will f ur th er r elieve t he ma nu factu r er
of r esp onsi b ility for per so na l injury or p rop er ty d am ag e r esult in g
th er efr om .
3. M an y e lectr ical an d m ech ani ca l p ar ts i n 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 i nsp ecti on n or ca n t he pr o 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, watt ag e, etc. Rep l acem en t
p arts wh ic h ha ve th ese sp eci al s afet y ch ar act 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 r ep la cem en t which do es n ot
h ave th e same saf ety ch ar act er ist ics as t he r eco mmen de d
r eplac ement par t sh own i n th e p ar ts l ist of S er vi ce 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. The
diff er enc e of th e G ND i s sho wn b y th e LIV E : (") side GND, the
ISO LATE D(NEUTRAL) : (#) side G ND and EARTH : ($) side
GN D. Do n't sh or t b et we en th e LIV E si d e GN D an d
ISO LATE D(NEUTRAL) side GND or EARTH sid e GND and
n ever mea sur e wit h a m ea sur ing a ppa ratus ( oscillo scop e etc.)
th e LI VE sid e GN D an d IS OLA TED(NE UTRAL ) sid e G ND or
EARTH side 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 adj u ste d (Se e
ADJU STM ENT OF B 1 POW E R SUPPL Y).
6. The high volta ge app lie d t o th e pictu r e tu be mu st con for m wit h
th at sp ecifi ed in S er vi ce m an ual. E xcessive h igh vo lt ag e ca n
cau se an incr e ase i n 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
prevent ed. If s evere arc ing occur s, remove t he AC power
immed iate l y an d de ter mi ne th e ca use b y vi sua l insp ect io n
( in cor rect in stallat i on, cr acke d or m elte d high vo lt age har n ess,
p oor so ld er ing, et c.) . To maint ai n the p rope r min im u m l e vel of
sof t X- Ray em issi on, c omp on en ts i n th e high vol tag 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 i ves 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
m eter or a hig h v oltag e pr ob e wit h a V TVM . Discha rg e th e
picture tube before attempting meter connection, by connecting
a clip le ad to th e gr ou nd f ra me a nd c onn ecti n g th e oth er end of
the lead through a 10k
Ω2W resi sto r to the an od e b utt on .
8. W hen se r vice i s r equ ir e d, ob ser ve th e or igina l l ea 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 dr ess in th e
hig h voltag e cir cuit a r ea. W her e a s hor t ci rcuit h as occu rre d,
th ose co mp on ent s tha t i ndica te evide nce of ove rhea ting sho uld
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 isol at io n
ch eck on the expo sed me tal p ar ts of t he cabin et ( a nte nn a
ter m ina ls, vid eo /au di o inpu t and ou tpu t t er min al s, Con tr ol kn obs,
m etal cabi n et, scr ewhe ad s, ea rph one jack, con tr ol shaf ts, etc.)
to be su re th e p rodu ct is s af e t o o pe r ate 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 im a 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 aving a
r etu rn p ath to t he chass is sho uld withs tan d a vol t 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 plianc e
r ate d 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 g enerally found
in t he ser vic e tr ade.
(2) Leakage Current Check
Pl ug th e A C lin e c ord d ir ect l y in to th e A C ou tl et ( d o n ot use a li n e
isol atio n tr ansf or mer du rin g this ch eck.) . U sin 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 art 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 pa th to t he chassis , t o a known go od ea rt h
gr ou nd (wa 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 area , th is mu st no t exce ed 0.2 mA AC
(r.m.s.).
"
""
"Alte rnate Che ck M ethod
Pl ug th e A C lin e c ord d ir ect l y in to th e A C ou tl et ( d o n ot use a li n e
isol atio n tr an sfor mer during t hi s che ck.) . Use an AC vo lt me ter
h avi ng 1 00 0 oh ms pe r volt or mor e sens it ivity i n th e fo llow ing
m ann er. Con nec t a 1 50 0Ω10W res ist or para ll e 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 arth gro un d (wa ter pipe , etc.) . M eas ur e th e A C vo lt ag e
acr oss th e r es ist or with th e AC vo l tm eter . M ove th e r esistor
con nec ti on to e ach exp ose d me tal par t, p art i cular ly a ny exp osed
m etal p ar t havi n g a r etu rn pat h to t he ch assis, an d m easu r e th e
AC voltag e ac ro ss the r es ist or . N o w, re verse th e pl u g i n th e AC
ou tl et and r e pe at eac h m ea sur emen t. An y vol t ag e me asu re d
must not e xc eed 0 .75V AC (r.m. s.). This c orresponds to 0.5mA
AC (r.m.s.).
However, in tropical are a, 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 R T
ACVOLTMETER
(HAVING 1000 Ω/V,
OR MOR E SENSITIVITY)
