Sharp 20GT-15, Руководство по обслуживанию

Страница: 5 / 40

3
20GT-15
IMPOR
T
ANT SER
VICE NO
TES
Maintenance and repair of this receiver should be done b
y
quali-
fied ser
vice per
sonnel onl
y
.
SER
VICE OF HIGH
V
O
L
T
A
GE SYSTEM AND PICTURE
TUBE
When servicing the high v
oltage system,
remo
ve static c
har
ge fr
om it b
y
Connecting a 10K ohm Resistor in series with an insulated wire (suc
h as
a test pr
obe) between picture tube da
g and 2nd anode lead.
(A
C line cor
d
should be disconnected fr
om A
C
outlet.)
1.
Picture tube in this receiver emplo
ys integral implosion pr
otection.
2.
Replace with tube of the same type n
umber f
or contin
ued saf
ety
.
3.
Do not lift picture tube b
y
the nec
k.
4.
Handle the picture tube onl
y when wearing shatterpr
oof gog
gles and
after disc
har
ging the high v
olta
g
e
completel
y
.
X-RA
Y
This receiver is designed so that an
y X-Ra
y radiation is kept to an abso-
lute Minim
um.
Since cer
tain malfunctions or ser
vicing ma
y pr
oduce po-
tentiall
y hazar
dous radiation with pr
olong
ed e
xposure at c
lose range
,
the f
ollo
wing precautions should be observed:
1.
When repairing the cir
cuit,
be sure not to increase the high v
oltage to
more than 28.7kV (at beam 0
µ
A) f
or the set.
2.
T
o
keep the set in a normal operation ,
be sure to make it function on
24.5kV
±
1.5kV (at beam 1100
µ
A) in the case of the set.
The set has
been factor
y - Adjusted to the abo
ve-mentioned high v
oltage
.
∴
If there is a possibility that the high v
olta
g
e
fluctuates as a result of
the repair
s,
ne
ver f
o
rg
et to chec
k f
or suc
h high v
olta
g
e
after the w
ork.
3
.
Do not substitute a picture tube with unauthorized types and/or brands whic
h ma
y cause e
xcess X-ra
y radiation.
BEFORE RETURNING
THE RECEIVER
Bef
ore returning the receiver to the user
, perf
orm the f
ollo
wing saf
ety
c
hec
ks.
1.
Inspect all lead dress to make cer
tain that leads are not pinc
hed or
that har
d
ware is not lodg
ed between the c
hassis and other metal par
ts
in the receiver
.
2.
Inspect all pr
otective de
vices suc
h as non-metallic contr
ol knobs,
in-
sulating fishpaper
s,
cabinet bac
ks,
adjustment and compar
tment co
v-
er
s or shields,
isolation resistor
-capacity netw
orks,
mechanical insu-
lator
s etc.
ADJUSTMENT PRECA
UTION
This model’
s setting are adjusted in tw
o diff
erent w
a
ys:
through the I2C b
us control and
in the con
v
entional analog manner
.
The adjustments via the I2C b
us control include
preset-only items and v
a
riab
le data.
1.
Setting the service mode b
y
the micr
opr
ocessor
.
(1).
Shor
t J
A
122 & J
A
124 f
or 1 second and release to s
witch to the ser
vice
mode position, and the microprocessor is in input mode
. (Adjustment through
the I2C b
us control).
(Use JWS K
e
y to set as w
ell).
(2).
Press the CH DO
WN / UP k
e
y on the remote controller to get ready to select
the mode one b
y
one
.
(3).
Press the CH DO
WN / UP k
e
y on the remote controller to select the modes
re
v
ersib
ly one b
y
one
.
(4).
Using the
V
OLUME UP/ DO
WN k
e
y on the remote controller
, the data can be
modified.
(5).
Shor
t J
A
122 & J
A
124 f
or 1 second and release to s
witch to the nor
mal mode
(OFF) position, and the microprocessor is in out of the ser
vice mode
.
2.
F
actor
y Presetting.
(1).
Shor
t J
A
122 & J
A
124 f
or 1 second and release to s
witch to the ser
vice
mode position and tur
n on the main po
wer s
witch.
Initial v
alues are automati-
cally preset, only when a ne
w EEPR
OM is used (J
udge with the first 4 b
ytes).
(2).
The initial data are preset as listed in page 4, 5, & 6.
(3).
Mak
e sure the data need modify or not (Initial data).
Note:
Once the chassis has been assemb
ly together and ready to be PO
WER ON
for the FIRST
TIME, mak
e sure to shor
t J
A
122 & J
A
124 to s
witch to the
ser
vice mode position first and then tur
n on the main po
w
er s
witch (See 2-(1)
abo
v
e).
Precaution:
If ha
v
en’t done this initiation, it ma
y possib
ly gener
ate e
xcessiv
e
Beam current.
3
.
For ref
erence please c
hec
k with memor
y map (U
A1 Series type RH-
IX3368CEN0 Attac
hment)