Sylvania 6720FDD User manual

SERVICEMANUAL
Sec. 1: Main Section
ISpecifications
IPreparation for Servicing
IAdjustment Procedures
ISchematic Diagrams
ICBA’s
Sec. 2: Deck Mechanism Section
IStandard Maintenance
IAlignment for Mechanism
IDisassembly/Assembly of Mechanism
Sec. 3: Exploded views
and Parts List Section
IExploded views
IParts List
20" COLOR TV/DVD/VCR
6720FDD

1-8-1 TD900EA
ELECTRICAL ADJUSTMENT INSTRUCTIONS
General Note:
"CBA" is abbreviation for "Circuit Board
Assembly."
NOTE:
Electrical adjustments are required after replacing
circuit components and certain mechanical parts.
It is important to perform these adjustments only
after all repairs and replacements have been com-
pleted.
Also, do not attempt these adjustments unless the
proper equipment is available.
Test Equipment Required
1. NTSC Pattern Generator (Color Bar W/White Win-
dow, Red Color, Dot Pattern, Gray Scale, Mono-
scope, Multi-Burst)
2. AC Milli Voltmeter (RMS)
3. Alignment Tape (FL8A, FL8N), Blank Tape
4. DC Voltmeter
5. Oscilloscope: Dual-trace with 10:1 probe,
V-Range: 0.001~50V/Div,
F-Range: DC~AC-60MHz
6. Frequency Counter
7. Plastic Tip Driver
How to make service remote control
unit:
1. Prepare normal remote control unit (Part No.
NE200UD). Remove 4 screws from the back lid
(Fig. 1-1).
2. Cut off pin 10 of the remote control microprocessor
and short circuit pins 10 and 17 of the microproces-
sor with a jumper wire
How to Set up the Service mode:
Service Mode:
1. Use the service remote control unit.
2. Turn the power on. (Use main power on the TV
unit.)
3. To enter the TV mode, press CH UP or CH DOWN
button on the TV unit.
4. Press "DISC MENU" button on the service remote
control unit. (Version of micro computer will display
on the CRT. (Ex: 057-001)
X-Ray Protection Test
X-Ray protection test should be done when replacing
any parts of this chassis.
1. Short test points J520 and J522 (on H.V. CBA).
2. Confirm that the main power turns off.
3. If the main power does not turn off, then replace
the following parts (D591, Q591, R592, R593,
R594 and IC1201).
4. Perform steps 1 to 3 again.
1. DC 114V (+B) Adjustment
Purpose: To obtain correct operation.
Symptom of Misadjustment: The picture is dark and
unit does not operate correctly.
Note: J521(+B), J535(GND) --- H.V. CBA,
VR2601 --- Power Supply/AV CBA
1. Connect the unit to AC Power Outlet.
2. Connect DC Volt Meter to J521(+B) and
J535(GND).
3. Adjust VR2601 so that the voltage of J521(+B)
becomes +114±0.5V DC.
SCREW
Fig. 1-1
Remote control unit (Bottom)
Test point Adj. Point Mode Input
J521
(+B)
J535
(GND) VR2601 --- -----
Tape M. EQ. Spec.
--- DC Voltmeter +114±0.5V DC

1-8-2 TD900EA
2. H Adjustment
Purpose: To get correct horizontal position and size of
screen image.
Symptom of Misadjustment: Horizontal position and
size of screen image may not be properly displayed.
Note: R583 --- H.V. CBA
1. Connect Frequency Counter to R583.
2. Operate the unit for at least 20 minutes.
3. Enter the Service mode. (See page 1-8-1.) Press
"2" button on the remote control unit and select H-
ADJ Mode.
4. Press CH o/ pbuttons on the remote control unit
so that the display will change "0" to "7."
5. At this moment, choose display "0" to "7" when the
Frequency counter display is closest to
15.734kHz±300Hz.
6. Turn the power off and on again.
3. C-Trap Adjustment
Purpose: To get minimum leakage of the color signal
carrier.
Symptom of Misadjustment: If C-Trap Adjustment is
incorrect, stripes will appear on the screen.
Note: D1304 (Cathode) (B-Out)--- Main CBA
1. Connect Oscilloscope to D1304 (Cathode).
2. Input a color bar signal from RF input.
Enter the Service mode. (See page 1-8-1.)
3. Press "0" button on the remote control unit and
select C-TRAP Mode.
4. Press CH o/ pbuttons on the remote control unit
so that the carrier leakage B-Out (3.58MHz) value
becomes minimum on the oscilloscope.
5. Turn the power off and on again.
Test point Adj. Point Mode Input
R583 CH o/ p
buttons Video ---
Tape M. EQ. Spec.
--- Frequency Counter 15.734kHz±300Hz
Test point Adj. Point Mode Input
D1304
(Cathode)
(B-OUT) CH o/ p
buttons --- Color Bar
Tape M. EQ. Spec.
--- Oscilloscope
Pattern Generator ---
Figure
minimum
Fig. 2

1-8-3 TD900EA
4. V. Size Adjustment
Purpose: To obtain correct vertical height of screen
image.
Symptom of Misadjustment: If V. Size is incorrect,
vertical height of image on the screen may not be
properly displayed.
1. Enter the Service mode. (See page 1-8-1.)
Press "9" button on the remote control unit and
select V-S Mode. (Press "9" button then display will
change to V-P and V-S).
2. Input monoscope pattern.
3. Press CH o/ pbuttons on the remote control unit
so that the monoscope pattern is 90±5% of display
size and the circle is round.
5. V. Shift Adjustment
Purpose: To obtain correct vertical position of screen
image.
Symptom of Misadjustment: If V. position is incor-
rect, vertical position of image on the screen may not
be properly displayed.
1. Enter the Service mode. (See page 1-8-1.)
Press "9" button on the remote control unit and
select V-P Mode. (Press "9" button then display will
change to V-P and V-S).
2. Input monoscope pattern.
3. Press CH o/ pbuttons on the remote control unit
so that the top and bottom of the monoscope pat-
tern are equal to each other.
6. H. Shift Adjustment
Purpose: To obtain correct horizontal position and
size of screen image.
Symptom of Misadjustment: Horizontal position and
size of screen image may not be properly displayed.
1. Enter the Service mode. (See page 1-8-1.)
Press "8" button on the remote control unit and
select H-P Mode.
2. Input monoscope pattern.
3. Press CH o/ pbuttons on the remote control unit
so that the left and right side of the monoscope pat-
tern are equal to each other.
4. Turn the power off and on again.
7. Cut-off Adjustment
Purpose: To adjust the beam current of R, G, B, and
screen voltage.
Symptom of Misadjustment: White color may be
reddish, greenish or bluish.
Test point Adj. Point Mode Input
--- CH o/ p
buttons --- Monoscope
Tape M. EQ. Spec.
--- Pattern Generator 90±5%
Test point Adj. Point Mode Input
--- CH o/ p
buttons --- Monoscope
Tape M. EQ. Spec.
--- Pattern Generator ---
Test point Adj. Point Mode Input
--- CH o/ p
buttons --- Monoscope
Tape M. EQ. Spec.
--- Pattern Generator ---
Test point Adj. Point Mode Input
--- Screen-Control Ext. Black
Raster /
White
Raster
Tape M. EQ. Spec.
--- Pattern Generator See Reference
Notes below
Figure
P
ATTERN GENERATOR
RF INPUT
Fig. 3

1-8-4 TD900EA
Notes: Screen Control FBT --- H.V. CBA
FBT= Fly Back Transformer
Use the Remote Control Unit
1. Degauss the CRT and allow CRT to operate for 20
minutes before starting the alignment.
2. Input the Black raster signal from EXT. input.
3. Enter the Service mode. (See page 1-8-1.)
4. Press the "VOL p" button.
(Press "VOL p" then display will change CUT OFF/
DRIVE, 7Fh adjustment and DVD-KEY).
5. Choose CUT OFF/DRIVE mode then press "1" but-
ton. This adjustment mode is CUT OFF (R).
6. Increase the screen control so that the horizontal
line just appears on the CRT.
7. Press the "CH o/ p" button until the horizontal line
becomes white.
8. Choose CUT OFF/DRIVE mode then press "2" but-
ton. This adjustment mode is CUT OFF (G). Press
"CH o/ p" until the horizontal line becomes white.
9. Choose CUT OFF/DRIVE mode then press "3" but-
ton. This adjustment mode is CUT OFF (B). Press
"CH o/ p" until the horizontal line becomes white.
10.Choose CUT OFF/DRIVE mode then press "4" but-
ton.
11.Input the White Raster Signal from Video In.
12.Adjust the RED DRIVE as needed with the CH o/
pbuttons to get the following value, X= 286, Y=
294.
13.Choose CUT OFF/DRIVE mode then press "5."
Adjust the BLUE DRIVE as needed with the CH o/
pbuttons to get the following value, X= 286, Y=
294.
14.Turn the power off and on again.
8. Sub-Brightness Adjustment
Purpose: To get proper brightness.
Symptom of Misadjustment: If Sub-Brightness is
incorrect, proper brightness cannot be obtained by
adjusting the Brightness Control.
Note: SMPTE Setup level --- 7.5 IRE
1. Enter the Service Mode. (See page 1-8-1.)
Then input SMPTE signal from RF input.
2. Press PICTURE button. (Press PICTURE button
then display will change BRT, CNT, COL, TNT, and
V-T). Select BRT and press CH o/ pbuttons so
that the bar is just visible (See above figure).
3. Turn the power off and on again.
Test point Adj. Point Mode Input
--- CH o/ p
buttons --- SMPTE 7.5IRE
Tape M. EQ. Spec.
--- Pattern
Generator See below
Figure
Black
W
hite
This b
ar
just
visible
Fig. 4