Sharp VC-A400U User manual

1
VC-A400U
VC-H800U
S39E7VC-A400U
SERVICE MANUAL
This document has been published to be used for
after sales service only.
Thecontentsaresubjecttochangewithoutnotice.
SHARP CORPORATION
VIDEO CASSETTE RECORDER
SERVICE MANUAL MODELS VC-A400U/H800U
VIDEO CASSETTE RECORDER
VC-A400U
VC-H800U
In the interests of user-safety (Required by safety regula-
tions in some countries) the set should be restored to its
originalconditionandonlypartsidenticaltothosespecified
be used.
MODELS VC-A400U
VC-H800U
Page
1. GENERAL INFORMATION............................................................................................................ 4
1-1 FEATURES ............................................................................................................................. 4
1-2 SPECIFICATIONS .................................................................................................................. 4
1-3 LOCATION OF MAJOR COMPONENTS AND CONTROL.....................................................5
2. DISASSEMBLY AND REASSEMBLY............................................................................................6
2-1 DISASSEMBLY OF MAJOR BLOCKS....................................................................................6
2-2 DISASSEMBLING THE MECHANISM/MAIN PWB ASSEMBLY............................................ 7
2-3 CARES WHEN REASSEMBLING...........................................................................................8
3. FUNCTION OF MAJOR MECHANICAL PARTS ...........................................................................9
4. ADJUSTMENT, REPLACEMENT AND ASSEMBLY OF MECHANICAL UNITS ........................ 11
4-1 MECHANISM CONFIRMATION ADJUSTMENT JIG ............................................................11
5. ELECTRICAL ADJUSTMENT...................................................................................................... 30
5-1 ADJUSTMENT OF HEAD SWITCHING POINT....................................................................31
5-2 ADJUSTMENT OF FV (False Vertical Sync) OF STILL PICTURE ...................................... 31
5-3 CHECKING OF OFF TRACK ................................................................................................31
5-4 ADJUSTMENT OF SIF-INPUT LEVEL .................................................................................32
5-5 ADJUSTMENT OF STEREO SEPARATION ........................................................................32
6. MECHANISM OPERATION FLOWCHART AND TROUBLESHOOTING GUIDE ...................... 33
7. TROUBLESHOOTING................................................................................................................. 39
8. BLOCK DIAGRAM....................................................................................................................... 50
9. SCHEMATIC DIAGRAM AND PWB FOIL PATTERN..................................................................58
10. REPLACEMENT PARTS LIST .................................................................................................... 73
11. EXPLODED VIEW OF MECHANICAL PARTS............................................................................81
12. PACKING OF THE SET .............................................................................................................. 85
CONTENTS

2
VC-A400U
VC-H800U
IMPORTANT SERVICE NOTES
WARNING :TOREDUCETHERISKOFFIREORELEC-
TRIC SHOCK, DO NOT EXPOSE THIS AP-
PLIANCE TO RAIN OR MOISTURE.
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK. DO
NOT REMOVE COVER. NO USER-SERVICEABLE
PARTS INSIDE. REFER SERVICING TO QUALIFIED
SERVICE PERSONNEL.
This symbol warns the user of uninsulated voltage
withintheunitthatcancausedangerouselectricshocks.
This symbol alerts the user that there are important
operatingandmaintenanceinstructionsintheliterature
accompanying this unit.
This symbol mark means fast operating fuse.
For continued protection against risk of fire, replace
only with same type fuse F901 (3.0A, 125V).
CAUTION:
BEFORE RETURNING THE VIDEO CASSETTE
RECORDER
Beforereturning thevideo cassetterecorder tothe user,
perform the following safety checks.
1. Inspect all lead dress to make certain that leads are
not pinched or that hardware is not lodged between
thechassisandothermetalpartsinthevideocassette
recorder.
2. Inspect all protective devices such as non-metallic
control knobs, insulation materials, cabinet backs,
adjustmentandcompartmentcoversorshields,isola-
tion resistor/capacitor networks, mechanical insula-
tors etc.
3. To be sure that no shock hazard exists, check for
current in the following manner.
●Plug the AC line cord directly into a 120 volt AC outlet
(Do not use an isolation transformer for this test).
●Using two clip leads, connect a 1.5k ohm, 10 watt
resistorparalleledbya0.15µFcapacitorinserieswith
all exposed metal cabinet parts and a known earth
ground, such as a water pipe or conduit.
●Use an SSVM or VOM with 1000 ohm per volt, or
higher, sensitivity or measure the AC voltage drop
across the resistor (See Diagram).
●Move the resistor connection to earth exposed metal
part having a return path to the chassis (antenna,
metalcabinet,screwheads,knobsandcontrolshafts,
SSVM
AC SCALE
1.5k ohms.
10W
CONNECT TO
KNOWN EARTH
GROUND
TO EXPOSED
METAL PARTS
0.15 µF
TEST PROBE
etc.) and measure the AC voltage drop across the
resistor. Reverse the AC plug on the set and repeat
AC voltage measurements for each exposed part.
Anyreading of 0.45Vrms (thiscorresponds to 0.3mA
rms AC.) or more is excessive and indicates a poten-
tial shock hazard which must be corrected before
returning the video cassette recorder to the owner.
3.0A 125V

3
VC-A400U
VC-H800U
PRECAUTIONS IN PART REPLACEMENT
When servicing the unit with power on, be careful to the section marked white all over.
This is the primary power circuit which is live.
When checking the soldering side in the tape travel mode, make sure first that the tape has been loaded and then turn
over the PWB with due care to the primary power circuit.
Make readjustment, if needed after replacement of part, with the mechanism and its PWB in position in the main frame.
(1) Start and end sensors: Q701 and Q702
Insert the sensor’s projection deep into the upper hole of the holder. Referring to the PWB, fix the sensors tight
enough.
(2) Photocoupler: IC901
Refer to the symbol on the PWB and the anode marking of the part.
(3) Cam switches A and B: D708 and D709.
Adjust the notch of the part to the white marker of the symbol on the PWB. Do not allow any looseness.
(4) Take-up and supply sensors: D707 and D706.
Be careful not to confuse the setting direction of the parts in reference to the symbols on the PWB. Do not allow any
looseness.

4
VC-A400U
VC-H800U
1. GENERAL INFORMATION
1-1 FEATURES
Only for VC-H800U
•Hi-Fi Stereo Sound
• Built-in MTS (Multi-channel TV Sound) Decoder
Common Features
• EZ Set Up
• S-VHS Quasi Playback
• Double-Azimuth 4-Heads
•19
µClear Picture System (in EP mode)
• HQ System for Better Resolution and Color Reproduction
• Multi-Language(English/Spanish/French)OSD(OnScreen
Display) with Menu Screen Guidance
• 181-channelPLLQuartzSynthesizedRandomAccessTuner
with Automatic Channel Setting
• Quick Start with Full Loading Mechanism
• 1-Year, 8 Event Programmable Timer
• Simple Recording Timer
• Unified Remote Control
• Sharp Super Picture
• 20 Seconds Timer Backup
• Field-Still/Variable Slow/Frame Advance
• Real-Time Counter (On Screen Display)
• Automatic Daylight Saving-Time (D.S.T.) Adjustment
• Blue Screen Noise Elimination
• Auto Tracking Control System
• Digital Program Search System (DPSS)
• Skip Search
• Instant Replay
• Auto Zero Back
• Recorded Section Auto Repeat
• Full Automatic Playback
• Tamper Proof
• Up to 8 Hours of Recording and Playback (with T-160
cassette)
1-2 SPECIFICATIONS
Format: VHS NTSC Standard
Video Recording System: Rotary Two-Head Helical Scanning
Number of Video Heads: 4
Video Signal Standard: NTSC Color System
Audio Recording System: 1 Stationary Head for Linear Audio
2 Rotary Heads for Hi-Fi stereo (Only Hi-Fi model)
Tape Width: 12.7 mm (1/2 inch)
Tape Speed: (SP) 33.35 mm/sec. (1.31 i.p.s.)
(LP) 16.67 mm/sec. (0.66 i.p.s.) (playback only)
(EP) 11.12 mm/sec. (0.44 i.p.s.)
Maximum Recording Time: (SP) 160 min. (T-160)
(EP) 480 min. (T-160)
Channel Coverage: VHF 2-13
UHF 14-69
CATV 1-125
Antenna Input: 75 Ohm
Video Input: 0.5 to 2.0 Vp-p, 75 Ohm unbalanced
Video Output: 1.0 Vp-p, 75 Ohm unbalanced
Audio Input: –8 dBs, 47 kOhm unbalanced (0 dBs = 0.775 Vrms)
Audio Output: –8 dBs, 1 kOhm unbalanced (0 dBs = 0.775 Vrms)
Hi-Fi Audio (Only for Hi-Fi model):
Dynamic Range: 90 dB
Frequency Response: 20 Hz-20 kHz
Memory Backup: 20 seconds
Operating Temperature: 5°C to 40°C (41°F to 104°F)
Storage temperature: –20°C to 60°C (–4°F to 140°F)
Power Source: 120 V AC, 60 Hz
Power Consumption: 20 W
Weight: 2.8 kg (6.2 lbs)
Dimensions (approx.): 360 (W) x 92 (H) x 253 (D) mm (14-3/16" x 3-5/8" x 9-31/32")
Accessories included: 75 ohm coaxial cable, Operation manual, Infrared remote control, Battery (2 pcs.),
Timer card
Note: Specifications are subject to change without notice.

5
VC-A400U
VC-H800U
1-3 LOCATION OF MAJOR COMPONENTS AND CONTROL
LED Indicator (explained throughout the operation Instruction)
1
1
POWER
2
TIMER
3
VCR
4
REC
5
TAMPER
PROOF
6
REMOTE SENSOR
POWER LED indicator This indicator lights up GREEN whenever the VCR is turned on.
2
TIMER LED indicator This indicator lights up when the VCR is set for timer recording, Simple Recording Timer and Recording with the Timer.
3
VCR LED indicator This indicator lights up when selecting "VCR" by using the TV/VCR button.
4
REC LED indicator This indicator lights up on during recording. This indicator flashes during REC-Pause.
5
TAMPER PROOF ( ) LED indicator This indicator lights up when the set mode is locked.
6
Remote Sensor Point Remote Control at this window.
POWER TIMER VCR REC TAMPER
PROOF REMOTE SENSOR
Cassette compartment (see Playback/Recording)
POWER button (When pressed to turn on the VCR, POWER LED indicator will light up GREEN. When the power is turned off. POWER LED indicator wil turn to RED.)
Basic function controls (see Playback/Recording)

6
VC-A400U
VC-H800U
B
C
A
B
5
9
6
10
11
7
8
3
3
C
1
A
12
2
4
2. DISASSEMBLY AND REASSEMBLY
2-1 DISASSEMBLY OF MAJOR BLOCKS
TOP CABINET : Remove 2 screws 1.
FRONT PANEL : Remove button 2.
Remove 2 screws 3and 7 clips 4.
OPERATION : Remove 1 screw 5.
PWB
SHIELD ANGLE : Remove 1 screw 6with shield angle.
MECHANISM/ : Remove 1 screw 7, 1 screw 8, 2
MAIN PWB screws 9, 2 screws 0. Remove 1
screwqwithantennaterminalcover.
Remove 1 screw wwith top cabinet
fix angle.
MAIN FRAME
FRONT PANEL
SHIELD
ANGLE
TOP CABINET
ANTENNA
TERMINAL
COVER
MECHANISM/
MAIN PWB
ASSEMBLY
TOP CABINET
FIX ANGLE
H/A SHIELD
TOP
OPERATION PWB
LED PWB

7
VC-A400U
VC-H800U
MECHANISM CHASSIS
2-2 DISASSEMBLING THE MECHANISM/MAIN PWB ASSEMBLY
1. When removing the mechanism from the main PWB,
remove the antenna cover 1 screw 1, and remove the
antenna terminal cover.
Remove the PWB bottom plate 1 screw 2.
RemovetheFFCcable(AA,AD,AH)3whichconnect-
ing the PWB and the mechanism.
Take out vertically the mechanism so that it does not
damage the adjacent parts.
2. Removing the mechanism and cassette housing.
Remove 2 screws 4fixing the cassette housing to the
mechanism, and remove the cassette housing.
2
1
3
4
CASSETTE
HOUSING
MAIN PWB

8
VC-A400U
VC-H800U
START SENSOR
2-3 CARES WHEN REASSEMBLING
INSTALLING THE CASSETTE HOUSING
When the cassette housing is installed on the mechanism,
the initial setting is essential condition.
Therearetwoinitialsettingmethods,namelyelectricaland
mechanical.
1. Electrical initial setting
So as to perform initial setting of mechanism execute the
Step1ofInstallationofcassettehousing.Afterascertaining
the return to the initial setting position (*1) install the
cassettehousing.(Conditions:WhenmechanismandPWB
have been installed)
2. Mechanical initial setting
Feed the pulley feed gear of loading motor with screw
driver.Afterascertainingthereturntotheinitialsetposition
(*1) install the cassette housing in the specified position.
(This method is applied only for the mechanism.)
INSTALLING THE MECHANISM ON PWB
Lower vertically the mechanism, paying attention to the
mechanismedge,andinstallthemechanismwithduecare
so that the parts are not damaged. So as to fix the mecha-
nismtothemainPWBinstalltwohousings.(Fittheantenna
cover to one of them. For other, fix the vicinity of loading
motor and solder joint side of main PWB.) Connect again
the FFC cable (AA-MH, AD-ME, AH-MH) between the
mechanism and the main PWB.
PARTS WHICH NEED PARTICULAR CARE
When installing the mechanism chassis on the PWB unit,
take care so as to prevent deformation due to contact of
mechanism chassis with REC TIP SW.
Pulley feed gear
Screwdriver
AE CONNECTOR
AL CONNECTOR
Casecon
drive gear
Drive angle of
cassette housing
REC TIP SW
END SENSOR
AC CONNECTOR
Tilt mark (*1)

9
VC-A400U
VC-H800U
3. FUNCTION OF MAJOR MECHANICAL PARTS (TOP VIEW)
No. Function No. Function
1 Full erase head
2 Supply pole base ass’y
3 Tension arm
4 Idler wheel ass’y
5 Pinch drive lever ass’y
6 Supply reel disk
7 Supply main brake
8 Take-up main brake
9 Pinch drive cam
10 A/C head ass’y
11 Reverse guide lever ass'y
12 Casecon drive gear
13 Take-up reel disk
14 Pinch roller lever ass’y
17
15 10
11
5
9
14
12
8
16
13
4
6
2
7
3
1
18

10
VC-A400U
VC-H800U
FUNCTION OF MAJOR MECHANICAL PARTS (BOTTOM VIEW)
No. Function No. Function
15 Drum ass’y
16 Loading motor
17 Drum drive motor
18 Take-up pole base ass’y
19 Slow brake lever
20 Master cam
21 Capstan D.D. motor
22 Reel belt
23 Clutch lever
24 Limiter pulley ass'y
26 Shifter
26
24
21
22
19
20
12
23