Hitachi C14-RF60, Service Manual

Page: 6 / 24

C14-RF60
7
7-1
7-2
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 B
U
S
CONTR
OL)
1.
Receiv
e "P
AL COLOUR BAR" signal.
»
Signal Strength: 57 ±1 dBµ
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 belo
w maxim
um v
oltage
.
4
.
Change the antenna input signal to 63~67dBµ
V
, and mak
e sure there is no noise
.
5.
T
u
rn
up the input signal to 90~95 dBµ
V to be
sure that there is no cross modulation beat.
Note:
For the 50 ohm signal strength gaug
e,
when not using 50/75
impedance adapter
, signal
strength is 52 ±1 dBµV(75 ohm open), instead of 57±1 dBµV (75 ohm open).
Precaution:
The loss of using impedance adapter
»
Bias box:
About 4.5 V
Oscilloscope
0.1V
TV Set
Bias box
TP201
+
+
—
—
T
uner IFT
(PRESET)
1.
Get the tuner ready to receiv
e the CH.
E - 9
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 IM-
PED
ANCE probe with w
a
v
e detector ;
see
Fig.1
) to the tuner's IF output ter
minal.
(
This ter
minal m
ust ha
v
e
the probe alone con-
nected ).
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
ef
or
m
as sho
wn in
Fig.
2
.
Note:
Be sure to k
eep the tuner co
v
e
r in position
dur
ing 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
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)
Fig. 4-1 Fig. 4-2
Fig. 4-3
1
PURITY ADJ
.
1
.
Receiv
e the GREEN-ONL
Y signal.
Adjust
the beam current to about 500 µ
A
.
2
.
Degauss the CR
T enough with the degausing
coil.
Note:
Follo
w the Job Instruction Sheet to
adjust the ma
gnetic field.
3.
Maintain the pur
ity magnet at the z
ero mag-
netic field and k
eep the static con
v
ergence
roughly adjusted.
4.
Obser
v
e
the points a, b as sho
wn in
Fig.
4-1
through the microscope
. Adjust the landing to
the r
ank A requirements
.
5.
Or
ient the raster rotation to 0 eastw
ard.
6.
Tighten up the deflection coil scre
ws.
»
Tightening
torque:
108 ± 20 N (11 ± 2 kgf)
7.
Mak
e sure the CR
T cor
ners landing meet the
A r
ank requirements
. If not, stic
k the magnet
sheet to correct it. Note:This adjustment m
ust be done after
warming up the unit f
or 30 minutes
or longer with a beam current o
ver
500 µA.
*
F
or the f
ollo
wing colours press R/C RGB k
ey
t
o
change
.
Green-only
Blue-only
Red-only
Signal-colour
screen cleared