Table of Contents
Advertisement
SECTION 2
DISASSEMBLY
2-2. LCD CASE AND B BOARD REMOVAL
2-1. CASE, A BOARD AND H BOARD REMOVAL
2
Three screws
2
LCD case (upper)
(7-685-105-19)
1 Battery cover
3
Battery case (lower)
3
A board
4
H board
5
Battery case (upper)
2-3. SERVICE POSITION
B board
J601
A board
CN401
CN301
AC power adaptor
CN201
H board
J101
Cord
Antenna
– 5 –
[SETUP](A BOARD )
1. Apply a DC voltage of 4.5V±0.1V to the J601 terminal (DC
input jack) on the A board.
2. With S601 on the A board at UHF position, set the User Con-
trol RV-550(VOL) and RV-901(BRT) on the H board to their
mechanical centers.
[+5.0V ALIGNMENT (RV600)](A BOARD )
Using a digital voltmeter measuring the voltage between
JL09 (+5.0V) and JL87 (A.GND). Adjust RV600 to obtain
4
the value shown below.
B board
LCD case (lower)
LCD holder
Standard Value = 4.55V± 0.02VDC
S601 position = UHF position
[+30.0V CHECK](A BOARD )
Check the voltage across JL07 (+30.0V) and JL87 (A.GND) .
Standard Value = 32.0V±2.0VDC
[+7.5V CHECK](A BOARD )
Check the voltage across JL08 (+7.5V) and JL87 (A.GND) .
1
Standard Value = 7.0V± 0.3VDC
Hinge collar
[-10.0V CHECK](A BOARD )
Check the voltage across JL10 (-10.0V) and JL87 (A.GND) .
Standard Value = -9.5V± 0.6VDC
- A board - (Component side)
RV600
J601
DC IN JACK
SECTION 3
CIRCUIT ADJUSTMENTS
< A BOARD ALIGNMENT >
3-1.VIF.AFT ROUGH ALIGNMENT (T201, T202)
[SETUP]
1. Set S601 on the A board to VHF position.
2. Apply no signal to JL119 (RF).
3. Connect a 1 kΩ resistor between JL09 (+5.0V) and
JL13 (RF AGC).
4. Apply a sweep signal across JL12 (IF) and JL14(IF GND).
(Fig. 3-1)
Note : Set the sweep signal for JL12 to -30±5dBm. Keep the
distance to the ATT output JL12 as short as possible.
SWEEP
MARKER
ATT
GENERATOR
75Ω 6dB
fo=45.75MHz±5kHz
Fig. 3-1
1. Connect an oscilloscope between JL86 (VIDEO) and JL87
(A.GND) and apply an external
obtain a waveform as shown in Fig. 3-2 (make sure not to
clip the extremely short portion).Adjust T202 so that the po-
sition at 45.75 MHz is the lowest point.
Note : Align JL26 (MGC) external voltage for approximately
a 1.0 Vp-p. Make sure that the JL26 (MGC) external
voltage does not exceed 4.3VDC.
2. Remove the external voltage (MGC) from JL26.
3. Connect an oscilloscope between JL02 (AFT) and JL01
(D.GND) and make a rough adjustment of T201 so that wave-
J601
form is close to zero at the 45.75 Mhz position.
EXT ANT
4. Remove the 1 kilohm resistor connected between JL09 (+5.0V)
RV002
RV004
and JL13 (RF AGC).
RV001
RV003
RV201
T201
T202
45.75MHz
0
Fig. 3-2
– 6 –
3-2.AFT FINE ADJUSTMENT (T201)
1. Connect a 1 kilohm resistor between JL09 (+5.0V) and JL13
(RF AGC).
Note : Perform this adjustment as the last step in the
process since drift may occur due to aging.
2. Switch the sweep signal to CW.
fo= 45.75 MHz±5 kHz, -30±5dBm
Apply the above signal between JL12 (IF) and JL14 (IF GND)
and then make a fine adjustment of T201 so that the level be-
tween JL02 (AFT) and JL01 (D.GND) reaches2.2V±0.4VDC.
3. Remove the 1 kilohm resistor connected between JL09 (+5.0V)
and JL13 (RF AGC).
3-3.RF. AGC ALIGNMENT (RV201)
1. Set S601 to VHF position and receive a VHF color bar signal
issued from a signal generator.
0.01µF
2. Adjust RV201 and align the screen for the optimal point so
that the snow noise disappears.
JL12
3-4.CHANNEL DiISPLAY POSITION ALIGNMENT
(RV001, RV002, RV004)
1. Set S601 to VHF position, a potentiometer (47kΩ±15kΩ)
across JL06(CS) and JL09 (+5.0 V) as shown in Fig. 2-6 and
short the points JL04(CH CAL) and JL01 (D.GND).
2. Receive channel 2 and align the channel display positions with
RV002(VP).
voltage (MGC) to JL26 to
3. Receive channel 13 and align the display bar with RV004(VA).
4. Align while performing tracking to mutual interference in the
above steps 2 and 3.
5. Receive channels 3 & 4 and confirm that the display bar is
within the standards.
6. Set S601 to UHF.
7. Receive channel 14 and align the display position with
RV001(UP).
8. Receive channel 69 and confirm that the display bar is within
the standards. If not within standards, align with RV001 so it
is within standards.
Once again receive channel 14 and confirm that the display bar
is within the standards.
Note : Use caution since shifting channel 69 will also
cause channel 14 to shift.
9. Remove the potentiometer (47kΩ+15kΩ) you connected be-
tween JL06(CS) and JL09(+5.0V). Also remove the short you
10Vp-p
connected between points JL04 (CH CAL)and JL01(D.GND).
JL06 (CS)
JL09(+5.0V)
Display bar
15kΩ
Channel No.
VR(47kΩ)
6
*Channel No. and display
bar are to be in line.
Fig. 3-4
Fig. 3-4
< B BOARD ALIGNMENT >
- B board -
RV302
(Component side)
RV301
RV308
RV306
3-5.V COM ALIGNMENT (RV302, RV306)
1. Adjust BRT VR (RV901) to1.740±0.005VDC, between
JL301(BRT) and JL307 (A.GND).
2. Observe the waveform across JL411 (V COM) and
JL407(GND).
3. Adjust RV302 (COM AMP) and RV306 (V COM DC) so that
the waveform resembles that in Fig. 3-5.
Note : The voltage at pin 37 (COMMON AMP) of IC302 shall
be a minimum of 1.8V.
5.0V±0.1Vp-p
0V
-1.4V±0.1Vp-p
Fig. 3-5
3-6.CONTRAST ALIGNMENT (RV301)
1. Receive the stepped waveform signal in 10 steps.
2. Observe the waveform across JL421(VG) and JL407(GND).
3. Align RV301 (CONT) so that 100IRE section matches the
standard below. (Fig. 3-6)
10thstep
(101IRE)
3.0V±0.1Vp-p
Fig. 3-6
3-7.COLOR PHASE (TINT) ALIGNMENT (RV-308)
1. Receive the color bar signal from the signal generator.
2. Observe the waveform across JL422(VB) and JL407(GND).
3. Adjust RV308 (TINT) so that the waveform level resembles
that of Fig. 3-7.
Align so the
portion is parallel and linear.
Fig. 3-7
– 7 –
Hide quick links:
Advertisement
Table of Contents
