Sharp CX34L3, Service Manual

Page: 7 / 50

7
7-1
7-2
CX34L3/51L3/51L4
PIF ADJUSTMENT
NO
.
Adjustment par
t
Adjusting pr
ocedure and conditions
W
a
vef
orm and other
s
1
Fig. 1
2
RF-A
GC
T
AKE O
VER
POINT ADJUSTMENT (I
2
C BUS
CONTR
OL)
1.
Receiv
e "P
AL COLOUR BAR" signal.
»
Signal Strength: 57
±
1 dB
µ
V (75 ohm open)
2
.
Connect the oscilloscope to
TP201 (T
uner’
s
A
GC
T
e
rminal) as sho
wn in
Fig.
3
.
3.
Call "A
GC" mode in ser
vice mode
. Adjust the
"A
GC" b
us data to obtain the
T
uner output pin
drop 0.1 V below maximum voltage.
4
.
Change the antenna input signal to 63~67dB
µ
V
, and mak
e sure there is no noise
.
5.
T
u
rn
up the input signal to 90~95 dB
µ
V to be
sure that there is no cross modulation beat.
Note:
For the 50 ohm signal strength gauge,
when not using 50/75
impedance adapter
, signal
strength is 52
±
1 dB
µ
V(75 ohm
open), instead of 57
±
1 dB
µ
V
(75 ohm open).
Precaution:
The loss of using impedance adapter
»
Bias bo
x:
About 4.5
V
Oscilloscope
0.1V
TV Set
Bias box
TP210
+
+
–
–
T
uner IFT
(PRESET)
1
.
Get the tuner ready to receiv
e the E-9 CH
signal, b
ut with no signal input.
Adjust the PLL data.
2
.
Connect the s
w
eep gener
ator's output cab
le
to the tuner antenna. (RF SWEEP)
3.
Adjust the s
w
eep gener
ator's to 80dBuV
.
4
.
Connect the response lead (use LO
W IMPED-
ANCE probe with w
a
v
e
detector
; see
Fig.1
) to
the tuner's IF output ter
minal.
(This ter
minal
must ha
v
e
the probe alone connected).
5.
Set the RF A
GC to 0 - 6
V with no satur
ation
with the w
a
v
e
fo
rm
.
6
.
Adjust the tuner IF coil to obtain the w
a
v
e
fo
rm
as sho
wn in
Fig.
2
.
Note:
B
e
sure to keep the tuner co
ver in
position during this adjustment.
E-9 CH
P
C
10k 100k
1n60
75ohm
IF OUT
-1.5+/-0.8dB 1000p
Oscilloscope
Fig. 2
Fig. 3
PURITY ADJUSTMENT
NO
.
Adjustment par
t
Adjusting pr
ocedure and conditions
W
a
vef
orm and other
s
1
PURITY ADJ
.
1.
Receiv
e the GREEN-ONL
Y signal.
Adjust the
beam current to ~ 700
µ
A (21") and ~ 500
µ
A
(14").
2
.
Degauss the CR
T enough with the degausing
coil.
Note :
Follow the Job Instruction Sheet to adjust the magnetic field.
V
e
rtical
Bv
:
- 0.050 mT
(- 0.50 gauss)
Horizontal Bh
:
+
0.020 mT
(0.20 gauss)
3
.
Maintain the purity magnet at the zero mag- netic field and keep the static convergence roughly adjusted.
4.
Observe the points a, b, as shown in
Fig. 1-1
through the microscope
. Adjust the landings
to A r
ank requirement.
5.
Orient the raster rotation to 0 eastward.
6.
Tighten up the deflection coil scre
ws
.
»
Tightening torque:
108N
±
20 N
(11kgf
±
2 kgf)
7.
Mak
e sure the CR
T cor
ners landing meet the
A rank requirements. If not, stick the magnet sheet to correct it.
Note:This adjustment m
ust be done after
warming up the unit f
or 30 min
utes or
long
er with a beam current o
v
er 700
µ
A
(For 14",
the beam current,
hould be o
ver
500
µ
A ).
Note:Set the service mode b
y
J
A137 &
J
A138 (shor
t) then press factor
y pr
oc-
ess R/C RGB ke
y to c
hang
e to RGB
mono colour mode
.
*
For the following colours press R/C RGB key to change.
*
Press R/C RGB key for 1 sec- ond in NORMAL MODE, the col- our will change to RGB mono colour mode.
a
b
A
B
A
B
A = B A = B
Rank "A"
(on the right of the CRT)
Rank "A"
(on the left of the CRT)
Green-only
Blue-only
Red-only
Signal-colour
screen cleared
Fig. 1-1 Fig. 1-2
Fig. 1-3