Hitachi VT-FX685A Service Manual

VT-FX685A
SERVICE MANUAL
PLAY
STOP/EJECT
REW F.FWD
REC/IRT
VIDEO-IN
AUDIO-INL R
POWER
CHANNEL
TRACKING
VT-FX685AC
CONTENTS
MAIN SECTION
Specifications .......................................................1- 1 -1
Important Safety Precautions ..............................1- 2 -1
Standard Notes for Servicing ...............................1- 3 -1
Preparation for Servicing .....................................1- 4 -1
Operating Controls and Functions .......................1- 5 -1
Cabinet Disassembly Instructions .......................1- 6 -1
Electrical Adjustment Instructions .......................1- 7 -1
Block Diagrams ....................................................1- 8 -1
Function Indicator Symbols ................................ 1- 8 -11
SchematicDiagrams / CBA' s and Test Points ...1- 9 -1
Waveforms ...........................................................1- 9 -8
Wiring Diagram ................................................1-10-1
System Control Timing Charts ..............................1-11-1
IC Pin Function .....................................................1-12-1
Lead Identifications ...............................................1-13-1
This video deck is VHS type video recorder. For proper operation, only the VHS type cassette must be used.
SPECIFICATIONS AND PARTS ARE SUBJECT TO CHANGE FOR IMPROVEMENT
VIDEO CASSETTE RECORDER
DECK MECHANISM SECTION
Standard Maintenance ......................................... 2- 1 -1
Fixture and Tape for Adjustment ......................... 2- 2 -1
Mechanical Alignment Procedures ...................... 2- 3 -1
Disassembly / Assembly Procedures of
Deck Mechanism ..... 2- 4 -1
Alignment Procedures of Mechanism .................. 2- 4 -9
EXPLODED VIEWS AND PARTS LIST SECTION
Exploded Views ................................................... 3- 1 -1
Mechanical Parts List ........................................... 3- 2 -1
Electrical Parts List .............................................. 3- 3 -1
May 2001
Digital Media Products Division, Tokai

MAIN SECTION

VIDEO CASSETTE RECORDER
VT-FX685A
VT-FX685AC
MAIN SECTION
Specifications
Preparation for Servicing
Adjustment Procedures
Schematic Diagrams
CBA’ s
TABLE OF CONTENTS
Specifications.................................................................................................................................................... 1- 1 -1
Important Safety Precautions............................................................................................................................ 1- 2 -1
Standard Notes for Servicing............................................................................................................................ 1- 3 -1
Preparation for Servicing .................................................................................................................................. 1- 4 -1
Operating Controls and Functions .................................................................................................................... 1- 5 -1
Cabinet Disassembly Instructions..................................................................................................................... 1- 6 -1
Electrical Adjustment Instructions..................................................................................................................... 1- 7 -1
Block Diagrams................................................................................................................................................. 1- 8 -1
Function Indicator Symbols..............................................................................................................................1- 8 -11
Schematic Diagrams / CBA’ s and Test Points ................................................................................................. 1- 9 -1
Waveforms........................................................................................................................................................ 1- 9 -8
Wiring Diagram ................................................................................................................................................. 1-10-1
System Control Timing Charts .......................................................................................................................... 1-11-1
IC Pin Function ................................................................................................................................................ 1-12-1
Lead Identifications........................................................................................................................................... 1-13-1

SPECIFICATIONS

Description Unit Minimum Nominal Maximum Condition
1. Video
1-1 Video Output (PB) Vp-p 0.8 1.0 1.2 1-2 Video Output (R/P) Vp-p 0.8 1.0 1.2 1-3 Video S/N Y (R/P) dB 41 44 SP Mode 1-4 Video Color S/N AM (R/P) dB 35 44 SP Mode 1-5 Video Color S/N PM (R/P) dB 33 37 SP Mode 1-6 Resolution (PB) Line 210 230 SP Mode
2. Servo
2-1 Jitter Low (R/P) µs 0.05 0.1 SP Mode 2-2 Wow & Flutter (R/P) % 0.2 0.4 SP Mode
3. Normal Audio
3-1 Output (PB) dBV -10 -6 -2 3-2 Output (R/P) dBV -10 -6 -2 SP Mode 3-3 S/N (R/P) dB 38 43 SP Mode 3-4 Distortion (R/P) % 2 4.0 SP Mode 3-5 Freq. response (R/P) at 200Hz dB -6 0 SP Mode (-20dB ref. 1kHz) at 8kHz dB -6 -1.5 SP Mode
4. Tuner
4-1 Video Output Vp-p 0.8 1.0 1.2 E-E Mode 4-2 Video S/N (S/N Y signal) dB 40 47 E-E Mode 4-3 Audio Output (1kHz) dBV -10 -6 -4 E-E Mode 4-4 Audio S/N (1kHz) dB 40 46 E-E Mode
Note: Nominal specs represent the design specs. All units should be able to approximate these – some will exceed and some may drop slightly below these specs. Limit specs represent the absolute worst condition that still might be considered acceptable; In no case should a unit fail to meet limit specs.
1-1-1

IMPORTANT SAFETY PRECAUTIONS

Product Safety Notice

Some electrical and mechanical parts have special safety-related characteristics which are often not evi­dent from visual inspection, nor can the protection they give necessarily be obtained by replacing them with components rated for higher voltage, wattage, etc. Parts that have special safety characteristics are identified by a # on schematics and in parts lists. Use of a substi­tute replacement that does not have the same safety characteristics as the recommended replacement part might create shock, fire, and/or other hazards. The Product’s Safety is under review continuously and new instructions are issued whenever appropriate. Prior to shipment from the factory, our products are carefully inspected to confirm with the recognized product safety and electrical codes of the countries in which they are to be sold. However, in order to maintain such compli­ance, it is equally important to implement the following precautions when a set is being serviced.

Precautions during Servicing

A.Parts identified by the # symbol are critical for
safety. Replace only with part number specified.
B.In addition to safety, other parts and assemblies are
specified for conformance with regulations applying to spurious radiation. These must also be replaced only with specified replacements.
Examples: RF converters, RF cables, noise block­ing capacitors, and noise blocking filters, etc.
C.Use specified internal wiring. Note especially:
1) Wires covered with PVC tubing
2) Double insulated wires
3) High voltage leads
D.Use specified insulating materials for hazardous live
parts. Note especially:
1) Insulation tape
2) PVC tubing
3) Spacers
4) Insulators for transistors
E.When replacing AC primary side components
(transformers, power cord, etc.), wrap ends of wires securely about the terminals before soldering.
F. Observe that the wires do not contact heat produc-
ing parts (heatsinks, oxide metal film resistors, fus­ible resistors, etc.).
G.Check that replaced wires do not contact sharp
edges or pointed parts.
H.When a power cord has been replaced, check that
5 - 6 kg of force in any direction will not loosen it.
I.Also check areas surrounding repaired locations.
J.Use care that foreign objects (screws, solder drop-
lets, etc.) do not remain inside the set.
K.Crimp type wire connector
The power transformer uses crimp type connectors which connect the power cord and the primary side of the transformer. When replacing the transformer, follow these steps carefully and precisely to prevent shock hazards.
Replacement procedure
1)Remove the old connector by cutting the wires at a point close to the connector.
Important: Do not re-use a connector. (Discard it.)
2)Strip about 15 mm of the insulation from the ends of the wires. If the wires are stranded, twist the strands to avoid frayed conductors.
3)Align the lengths of the wires to be connected. Insert the wires fully into the connector.
4)Use a crimping tool to crimp the metal sleeve at its center. Be sure to crimp fully to the complete closure of the tool.
L.When connecting or disconnecting the internal con-
nectors, first, disconnect the AC plug from the AC outlet.
1-2-1

Safety Check after Servicing

Examine the area surrounding the repaired location for damage or deterioration. Observe that screws, parts, and wires have been returned to their original positions. Afterwards, do the following tests and confirm the speci­fied values to verify compliance with safety standards.
1. Clearance Distance
When replacing primary circuit components, confirm specified clearance distance (d) and (d’) between sol­dered terminals, and between terminals and surround­ing metallic parts. (See Fig. 1)
Table 1 : Ratings for selected area
AC Line Voltage Clearance Distance (d) (d’)
120 V 3.2 mm (0.126 inches)
Note: This table is unofficial and for reference only. Be sure to confirm the precise values.
2. Leakage Current Test
Confirm the specified (or lower) leakage current be­tween B (earth ground, power cord plug prongs) and externally exposed accessible parts (RF terminals, an­tenna terminals, video and audio input and output ter­minals, microphone jacks, earphone jacks, etc.) is lower than or equal to the specified value in the table below.
Measuring Method (Power ON) :
Insert load Z between B (earth ground, power cord plug prongs) and exposed accessible parts. Use an AC voltmeter to measure across the terminals of load Z. See Fig. 2 and the following table.
Z
1.5k
Chassis or Secondary Conductor
Primary Circuit Terminals
dd'
Exposed Accessible Part
AC Voltmeter
0.15µF
Earth Ground
B
Power Cord Plug Prongs
(High Impedance)
Fig. 1
Fig. 2
Table 2 : Leakage current ratings for selected areas
AC Line Voltage Load Z Leakage Current (i) Earth Ground (B) to:
120 V
Note: This table is unofficial and for reference only. Be sure to confirm the precise values.
0.15µF CAP. & 1.5kΩ RES.
Connected in parallel
i 0.5mA Peak Exposed accessible parts
1-2-2

STANDARD NOTES FOR SERVICING

Circuit Board Indications

a.The output pin of the 3 pin Regulator ICs is indicated
as shown.
Top View
Out
b.For other ICs, pin 1 and every fifth pin are indicated
as shown.
Input
In
Bottom View
5
Pin 1
10
c.The 1st pin of every male connector is indicated as
shown.
Pin 1

Instructions for Connectors

1.When you connect or disconnect the FFC (Flexible Foil Connector) cable, be sure to first disconnect the AC cord.
2.FFC (Flexible Foil Connector) cable should be in­serted parallel into the connector, not at an angle.

How to Remove / Install Flat Pack-IC

1. Removal
With Hot-Air Flat Pack-IC Desoldering Machine:
(1)Prepare the hot-air flat pack-IC desoldering ma-
chine, then apply hot air to the Flat Pack-IC (about 5 to 6 seconds). (Fig. S-1-1)
Fig. S-1-1
(2)Remove the flat pack-IC with tweezers while apply-
ing the hot air.
(3)Bottom of the flat pack-IC is fixed with glue to the
CBA; when removing entire flat pack-IC, first apply soldering iron to center of the flat pack-IC and heat up. Then remove (glue will be melted). (Fig. S-1-6)
(4)Release the flat pack-IC from the CBA using tweez-
ers. (Fig. S-1-6)
Caution:
1.Do not supply hot air to the chip parts around the flat pack-IC for over 6 seconds because damage to the chip parts may occur. Put masking tape around the flat pack-IC to protect other parts from damage. (Fig. S-1-2)
2.The flat pack-IC on the CBA is affixed with glue, so be careful not to break or damage the foil of each pin or the solder lands under the IC when removing it.
FFC Cable
Connector
CBA
* Be careful to avoid a short circuit.
1-3-1
CBA
Masking Tape
Tweezers
Hot-air Flat Pack-IC Desoldering Machine
Flat Pack-IC
Fig. S-1-2
With Soldering Iron:
(1)Using desoldering braid, remove the solder from all
pins of the flat pack-IC. When you use solder flux which is applied to all pins of the flat pack-IC, you can remove it easily. (Fig. S-1-3)
(4)Bottom of the flat pack-IC is fixed with glue to the
CBA; when removing entire flat pack-IC, first apply soldering iron to center of the flat pack-IC and heat up. Then remove (glue will be melted). (Fig. S-1-6)
(5)Release the flat pack-IC from the CBA using tweez-
ers. (Fig. S-1-6)
Flat Pack-IC
Desoldering Braid
Soldering Iron
Fig. S-1-3
(2)Lift each lead of the flat pack-IC upward one by one,
using a sharp pin or wire to which solder will not adhere (iron wire). When heating the pins, use a fine tip soldering iron or a hot air desoldering machine. (Fig. S-1-4)
Sharp Pin
Note:
When using a soldering iron, care must be taken to ensure that the flat pack-IC is not being held by glue. When the flat pack-IC is removed from the CBA, handle it gently because it may be damaged if force is applied.
Hot Air Blower
or
Iron Wire
Soldering Iron
To Solid Mounting Point
Fig. S-1-5
Fine Tip
Fig. S-1-4
Soldering Iron
(3)Bottom of the flat pack-IC is fixed with glue to the
CBA; when removing entire flat pack-IC, first apply soldering iron to center of the flat pack-IC and heat up. Then remove (glue will be melted). (Fig. S-1-6)
(4)Release the flat pack-IC from the CBA using tweez-
ers. (Fig. S-1-6)
With Iron Wire:
(1)Using desoldering braid, remove the solder from all
pins of the flat pack-IC. When you use solder flux which is applied to all pins of the flat pack-IC, you can remove it easily. (Fig. S-1-3)
(2) Affix the wire to a workbench or solid mounting point,
as shown in Fig. S-1-5.
(3)While heating the pins using a fine tip soldering iron
or hot air blower, pull up the wire as the solder melts so as to lift the IC leads from the CBA contact pads as shown in Fig. S-1-5.
CBA
Tweezers
Fine Tip Soldeing Iron
Flat Pack-IC
Fig. S-1-6
1-3-2
2. Installation
(1)Using desoldering braid, remove the solder from the
foil of each pin of the flat pack-IC on the CBA so you can install a replacement flat pack-IC more easily.
(2)The " ● " mark on the flat pack-IC indicates pin 1.
(See Fig. S-1-7.) Be sure this mark matches the 1 on the PCB when positioning for installation. Then pre- solder the four corners of the flat pack-IC. (See Fig. S-1-8.)
(3)Solder all pins of the flat pack-IC. Be sure that none
of the pins have solder bridges.
Example :
Pin 1 of the Flat Pack-IC is indicated by a " " mark.
Fig. S-1-7

Instructions for Handling Semiconductors

Electrostatic breakdown of the semiconductors may occur due to a potential difference caused by electro­static charge during unpacking or repair work.
1. Ground for Human Body
Be sure to wear a grounding band (1M) that is properly grounded to remove any static electricity that may be charged on the body.
2. Ground for Workbench
Be sure to place a conductive sheet or copper plate with proper grounding (1MΩ) on the workbench or other surface, where the semiconductors are to be placed. Because the static electricity charge on clothing will not escape through the body grounding band, be careful to avoid contacting semiconductors with your clothing.
< Incorrect >
CBA
Presolder
Flat Pack-IC
CBA
< Correct >
Grounding Band
Fig. S-1-8
1M
CBA
1M
Conductive Sheet or Copper Plate
1-3-3

PREPARATION FOR SERVICING

How to Enter the Service Mode

About Optical Sensors
Caution:
An optical sensor system is used for the Tape Start and End Sensors on this equipment. Carefully read and follow the instructions below. Otherwise the unit may operate erratically.
What to do for preparation
Insert a tape into the Deck Mechanism Assembly and press the PLAY button. The tape will be loaded into the Deck Mechanism Assembly. Make sure the power is on, connect TP502 (SENSOR INHIBITION) to TP511 (GROUND). This will stop the function of Tape Start Sensor, Tape End Sensor and Reel Sensors. (If these TPs are connected before plugging in the unit, the function of the sensors will stay valid.) See Fig. 1.
Note: Because the Tape End Sensors are inactive, do not run a tape all the way to the start or the end of the tape to avoid tape damage.
About REC-Safety Switch
Caution:
The REC-Safety Switch is directly mounted on the Main CBA. When the Deck Mechanism Assembly is removed from the Main CBA for servicing, this switch does not work automatically.
What to do for preparation
In order to record, press the Rec button while pushing REC-SAFETY SW on the Main CBA. See Fig. 1.
CN501
Q503
CN251
SW506
(REC-SAFETY SW)
CN504
TP511
GND
CN502
CN503
Q504
TP502
S-INH
Fig. 1
1-4-1

OPERATING CONTROLS AND FUNCTIONS

Model: VT-FX685A / VT-FX685AC
VCR FRONT PANEL
AUDIO-INLR
VIDEO-IN
27
30
VCR REAR PANEL
25
25
1
POWER
6
CHANNEL
TRACKING
91087
26
26
AUDIO
OUT
VIDEO
OUT
OUT IN
OUT IN
29 30 3231
29 30 3231
2 3 4 5
REC/IRT
27
L
IN
R
AUDIO
L
CH3 CH4
IN
R
VIDEO
CH3 CH4
1.Cassette Compartment
2.REW button– Press to rewind the tape, or to view
the picture rapidly in reverse during the playback mode. (Rewind Search)
s
button– Press to cancel a setting of timer pro-
gram. Press to correct digits when setting program (For example: setting clock or timer program). Press to add or delete channel numbers during channel preset. (only on the remote control)
3. STOP button– Press to stop the tape motion. EJECT button– Press to remove a tape from the
VCR. (only on the VCR) button– Press to enter digits when setting pro-
gram (For example: setting clock or timer program). Press to select the setting modes from the on screen menu. (only on the remote control)
4.PLAY button– Press to begin playback. button– Press to enter digits when setting pro-
gram (For example: setting clock or timer program). Press to select the setting modes from the on screen menu. (only on the remote control)
5.F.FWD button– Press to rapidly advance the tape, or view the picture rapidly in forward during play­back. (Forward Search)
B button– When setting program (For example: setting clock or timer program), press to determine your selection and proceed to the next step you want to input. Press to determine the setting modes from the on screen menu. Press to add or delete channel numbers during channel preset. (only on the remote control)
27
STOP/EJECT
ANT
REW F.FWD
28
28
IN
ANT
OUT
IN
OUT
REMOTE CONTROL
PLAY
POWER
6
123
11
12 13
456
789
TAPE SPEED
DISPLAYMENU
14
2 3
10 24
REW
REC
VCR PIus+
0
PLAY
STOP
CATV
TVVCR
VCR/TV
CH
ENTER
+100
MUTE
VOL
F.FWD
PAUSE
SLOW
SEARCH MODE
EXIT COUNTER
RESET
MEMORY
6.POWER button– Press to turn VCR on and off.
Press to activate timer recording.
7.Remote sensor window– Receives the infrared
signals from the remote control.
8.Digital display
A B C
D E F
A.PWR. (Power) indicator– Indicates that the power
is turned on.
B.Cassette indicator– Indicates that there is a tape
in the VCR.
C.VCR indicator– Indicates that the VCR is in the
VCR position.
D.REC indicator– Indicates that it is recording.
Flashes when a recording has been paused.
E.w (Timer) indicator– Indicates that the timer recording
or an IRT recording has been set.
F. CLOCK indicator– Displays current time. PM indi-
cator appears when p.m.
9.CHANNEL(CH) / buttons– Press to select the
desired channels for viewing or recording. Tracking function– Press to minimize video ‘noise’
(lines or dots on screen) during playback (only on the VCR) or slow mode.
Press to stabilize the picture in the Still mode when the picture begins to vibrate vertically.
23
22
9
21 20
4 5
19 18
17 16
15
1-5-1
10.REC button– Press for manual recording. IRT button– Press to activates Instant Recording
Timer. (only on the VCR)
11.NUMBER buttons– Press to select desired chan­nels for viewing or recording. To select channels from 1 to 9, first press "0" button then 1 to 9. (only on the remote control)
+100 button– When selecting cable channels which are higher than 99, press this button first, then press the last two digits. (To select channel 125, first press "+100" button then press "2" and "5"). (only on the remote control)
ENTER– (only on the remote control)
12.TAPE SPEED button Press to choose the desired
recording speed : SP/SLP. (only on the remote control)
13. MENU button– Press to display the menu on the TV screen. Press to exit the menu on the TV screen. (only on the remote control)
14.DISPLAY button– Press to display the current time, channel number, real time tape counter, and other information on the TV screen. (only on the remote control)
Each time you press this button, TV screen will change as shown. The status display (STOP, PLAY etc.) and the tape speed display (SP, LP (playback only), or SLP) will disappear after 5 seconds.
<OFF mode>
<COUNT mode> <CLOCK mode>
Press once
STOP
SP 0:12:34
Press once
Press
once
STOP
SP
5:40PM
CH 02
15.COUNTER RESET button– Press to reset counter to 0:00:00. (only on the remote control)
EXIT button– Press to exit the menu on the TV screen. (only on the remote control)
16.COUNTER MEMORY button– Press to set counter memory on and off. (only on the remote control)
17.SEARCH MODE button– Press to perform a Time Search or an Index Search. (only on the remote con­trol)
18. PAUSE button– Press to temporarily stop the tape
during recording or to view a still picture during playback. (only on the remote control)
Frame Advance function– Press to advance the picture by one frame at a time during the still mode. (only on the remote control)
19. SLOW button– Press to start slow motion playback.
(only on the remote control)
20.MUTE button– Press to mute the TV’s sound. Press
it again to resume the sound. (only on the remote control)
21.VOL(ume) buttons– Press to adjust the desired
TV’s volume level by using either or button. (only on the remote control)
22.VCR/TV button– Press to select TV or VCR mode.
(only on the remote control) VCR position: to view playback, to monitor video
recordings or watch TV using the VCR tuner. TV position: to watch TV or to view one program
while recording another.
23.MODE SELECT buttons
(only on the remote control)
CATV button TV button VCR button
24.VCR Plus+ button– Press to program the automat-
ic timer recording using the VCR Plus+ system. (only on the remote control)
25.Power cord– Connect to a standard AC outlet
(120V/60Hz).
26.AUDIO OUT jacks– Connect to the audio input
jacks of your audio equipment or another VCR.
27.AUDIO IN jacks– Connect to the audio output jacks
of your audio equipment or another VCR.
28.ANT. IN terminal– Connect to an antenna, Cable
system or Satellite system.
29.VIDEO OUT jack– Connect to the video input jack
of your video camera or another VCR.
30.VIDEO IN jack– Connect to the video output jack of
your video camera or another VCR.
31.CH3/CH4 selector switch– Use to select a video
output channel (3 or 4) for VCR playback.
32.ANT. OUT terminal– Connects to the antenna input
terminal on your TV.
1-5-2

CABINET DISASSEMBLY INSTRUCTIONS

1. Disassembly Flowchart

This flowchart indicates the disassembly steps to gain access to item(s) to be serviced. When reassembling, follow the steps in reverse order. Bend, route, and dress the cables as they were originally.
[1] Top Case
[2] Front Assembly
[3] Deck Assembly
[4] Cylinder Shield
[5] REC Arm Assembly
[6] Main CBA
[7] Function CBA

Disassembly Method

REMOVAL
ID/
LOC.
No.
[1] Top Case 1 3(S-1) -
[2]
[3]
[4]
[5]
[6] Main CBA 4 *2(L-4) -
[7]
PART
Front Assembly
Deck Assembly
Cylinder Shield
REC Arm Assembly
Function CBA
REMOVE/
Fig.
*UNHOOK/UNLOCK/
No.
RELEASE/UNPLUG/ DESOLDER
2 *3(L-1), *4(L-2)
3 6(S-2), Spacer,
*(CN251, CN501, CN502, CN503, CN504)
32(S-3)
3 ----------
4 *(L-3), Desolder
Note
-
1, 2
-
-
3
Reference Notes
CAUTION: Locking Tabs (L-1) and (L-2) are fragile. Be careful not to break them.
1. Remove six Screws (S-2) and the Spacer. Then slowly lift the Deck Assembly up. Lifting Deck As­sembly disconnects five Connectors (CN251, CN501, CN502, CN503, CN504). (Fig. 3)
2. Before installing the Deck Assembly, be sure to place the pin of LD-SW on Main CBA as shown in Fig. 5. Then, install the Deck Assembly while align­ing the hole of Cam Gear with the pin of LD-SW, the shaft of Cam Gear with the hole of LD-SW as shown in Fig. 5.
3. After removing the Main CBA, desolder from bottom of the Main CBA as shown in Fig. 4 to remove the Function CBA.
(S-1)
[1]Top Case
1 : Identification (location) No. of parts in the figures 2 : Name of the part 3 : Figure Number for reference 4 : Identification of parts to be removed, unhooked, un-
locked, released, unplugged, unclamped, or desoldered. P=Spring, L=Locking Tab, S=Screw, CN=Connector *=Unhook, Unlock, Release, Unplug, or Desolder e.g. 2(S-2) = two Screws (S-2), 2(L-2) = two Locking Tabs (L-2)
5 :Refer to "Reference Notes."
Fig. 1
1-6-1
(L-2)
(L-2)
(S-2)
(L-1)
(S-3)
Spacer
CN501
[2]Front Assembly
Fig. 2
[4]Cylinder Shield
(S-3)
(S-2)
[3]Deck Assembly
CN504
CN502
Desolder from bottom
(L-4)
[6]Main C.B.A.
[6]Main C.B.A.
[7]Function C.B.A.
(L-4)
(L-3)
Fig. 4
Pin
SW507 LD-SW
[4]REC Arm Assembly
CN251
CN503
Fig. 3
1-6-2
[4]Deck Assembly
Shaft
Hole
LD-SW
Cam Gear
Hole
Pin
[6]Main C.B.A.
Fig. 5

ELECTRICAL ADJUSTMENT INSTRUCTIONS

General Note: "CBA" is an abbreviation for "Circuit Board Assembly."
NOTE:
1.Electrical adjustments are required after replacing circuit components and certain mechanical parts. It is important to do these adjustments only after all repairs and replacements have been completed. Also, do not attempt these adjustments unless the proper equipment is available.
2.To perform these alignment / confirmation proce­dures, make sure that the tracking control is set in the center position: Press either channel "" or "▲" button first, then the "PLAY" button (VCR’s Front Panel only).
CH1
CH2
Figure 1
EXT. Syncronize Trigger Point
1.0H
6.5H
Switching Pulse
V-Sync
0.5H

Test Equipment Required

1.Oscilloscope: Dual-trace with 10:1 probe, V-Range:
0.001~50V/Div., F-Range: DC~AC-20MHz
2.Alignment Tape (MH-1)
Head Switching Position Adjust­ment
Purpose:
To determine the Head Switching point during play­back.
Symptom of Misadjustment:
May cause Head Switching noise or vertical jitter in the picture.
Test Point Adj. Point Mode Input
TP751(V-OUT)
TP302(RF-SW)
TP511(GND)
Tape
MH-1 Oscilloscope
Connections of Measurement Equipment
VR501
(Switching Point)
(MAIN CBA)
Measurement
Equipment
PLAY
(SP)
6.5H±1H
(412.7µs±60µs)
----
Spec.
Reference Notes:
Play back the Alignment tape and adjust VR501 so that the V-sync front edge of the CH1 video output waveform is at the 6.5H(412.7µs) delayed position from the rising edge of the CH2 head switching pulse waveform.
Main CBA
Oscilloscope
TP751 TP511 TP302
CH1 CH2 Trig. (+)
1-7-1

Servo/System Control Block Diagram BLOCK DIAGRAMS

(DECK ASSEMBLY)
AC HEAD ASSEMBLY
CONTROL HEAD
CYLINDER ASSEMBLY
DRUM MOTOR
PG SENSOR
LOADING MOTOR ASSEMBLY
LOADING MOTOR
CAPSTAN MOTOR
CAPSTAN MOTOR
M
M
M
CN287
5 8CTL(+) 6 9CTL(-)
AL+15.5V/+12V
FG-GND
MAIN CBA
CN504
CN502 1D-W 2D-V 3D-U 4D-COM 5PG-IN
CN504 1LD-M(+) 2LD-M(-)
CN503 1C-F/R 2P-ON+5V 3 4C-FG 5C-POW-SW 6C-CONT 7 8CM-GND
IC301
TP303
CTL
P-ON+5V AL+15.5V/+12V
(Y/C PROCESS)
CONTROL AMP
9 23 19
IC506
(DRUM /LOADING MOTOR DRIVE)
25 24 22 21 15 16 17
4 2
+
-
DRIVE
TP506 TP505
ST-S
Q504
ST-S
18
DRUM MOTOR DRIVE
LOADING MOTOR CONTROL
Q503
END-S
AL+5V
D555 S-LED
T-REEL
Q506
T-REEL
TIMER+5V
14
20
18
9
SW507 LD-SW
AL+5V
RS501
REMOTE SENSOR
TP510
LD-SW
PS502
S-REEL
Q501
RESET
VR501 SW-POINT
AL+5V
AL+5V
IC501
(SERVO/SYSTEM CONTROL)
KEY- 1
KEY- 2
REMOCON-IN
1
PB-CTL
54
REC-CTL(-)
20 19
REC-CTL(+)
LD-SW74
D-CONT56
D-FG
52
D-PG
53
LM-
59
FWD/REV
75
ST-S
68
END-S T-REEL
49
S-REEL
50
34
RESET
C-F/R
48
51
C-FG C-POW-SW46 C-CONT
55
71
PG-DELAY
I2C-BUS-CLK
I2C-BUS-DATA
Hi-Fi-CLK Hi-Fi-DATA Hi-Fi-H-SW
Hi-Fi-CS
Hi-Fi/NOR-IN
ST/SAP-IN
A-MUTE-H
D-REC-H
REC-SW
D-PB-H
INSEL/ST-SL
C-SYNC
D-V SYNC
V-ENV
C-ROTA
RF-SW
TRICK/C-G/APC
SP/LP/SLP
BLUEBACK-ON
H-A-SW
H-A-COMP
P-ON-L
P-DOWN-L
72
73
G1
81
G4 84
a
85
d
88
e
94
f 89
j
93
10
11 12 18
65 67
13 62 25
61
21 33 70 15 17 47 45 66 16 14
60 63
TP502
S-INH
KEY SWITCH
TP511
GND
9
8
SW506
REC SW
7
CN507 CN651
3 1KEY 2
DRIVE
Q645~Q648
5
6
TU701(TUNER UNIT)
10
11
ST/SAP-MODE
AL+5V
INSEL/ST-SL
TRICK/C-G/APC
BLUEBACK-ON
FUNCTION CBA
KEY SWITCH
FIP502
LED DISPLAY
IC505
(MEMORY)
SDA
SCL
CLOCK
DATA
Hi-Fi-CLK Hi-Fi-DATA Hi-Fi-H-SW
Hi-Fi-CS
NORMAL-H
A-MUTE-H
A-MUTE-H
D-REC-H
D-PB-H
D-REC-H
D-PB-H
C-SYNC
D-V SYNC
V-ENV
C-ROTA
RF-SW
SP/LP/SLP
H-A-SW
H-A-COMP
P-ON-L
P-DOWN-L
C-POW-SW
TO Hi-Fi AUDIO BLOCK
TO AUDIO BLOCK
FROM/TO VIDEO BLOCK
FROM/TO POWER SUPPLY BLOCK
1-8-1 1-8-2

Video Block Diagram

REC VIDEO SIGNAL PB VIDEO SIGNAL MODE: SP/REC
JK751 V-OUT
TU701
VIDEO-IN
VIDEO-OUT
JK752 REAR V-IN
JK753 FRONT V-IN
5
21
WF1
TP751 V-OUT
Q391
BUFFER
IC501
CHARA-OUT
BLUEBACK
OSD-
OSD-
30
IC301
(Y/C PROCESS)
3131
30
TUNER
42
REAR
38
40
FRONT
BLUEBACK
V-AGC
35
6dB
AMP
CHARA
MIX
FBC
R P
Y/C MIX
MAIN CBA
45 47 49 44
CCD 1H
DELAY
DOC YNR Y/C COMB
CHROMINANCE
SIGNAL PROCESS
Q301
BUFFER
LUMINANCE
SIGNAL PROCESS
FROM/TO SERVO/SYSTEM CONTROL BLOCK
(DECK ASSEMBLY)
CYLINDER ASSEMBLY
VIDEO (R)-1 HEAD
VIDEO (L)-1 HEAD
VIDEO (L)-2 HEAD
VIDEO (R)-2 HEAD
INSEL/ST-SL D-PB-H
D-REC-H TRICK/C-G/APC
C-SYNC C-ROTA D-V SYNC SP/LP/SLP BLUEBACK-ON
71 16
REC/EE/PB
D-REC-H
11
TRICK/C-G/APC
73 34
C-ROTA
14
D-V SYNC
39
SP/LP/SLP
59
BLUEBACK-ON
41
SYNC SEPA
R
P
AGC AMP
CN251 1 2 3 4 5 6
V(R)-1
V-COM V(L)-1 V(L)-2
V-COM V(R)-2
91 90 89 88 85 84 83 82
R L
SP
EP
L R
HPF
ENV DET
74
R
P
TP302
RF-SW
FROM/TO SERVO/SYSTEM CONTROL BLOCK
WF2
RF-SW V-ENV H-A-SW H-A-COMP
13 93 15
H-A-COMP
94
TP301
C-PB
WF5
1-8-3 1-8-4

Audio Block Diagram

PB-AUDIO SIGNAL REC-AUDIO SIGNAL Mode : SP/REC
TU701
SIF OUT
AUDIO-IN
JK751
A-OUT (R)
A-OUT (L)
REAR
A-IN (L)
A-IN (R)
A-IN (L)
FRONT
A-IN (R)
JK752
JK754
JK755
(DECK ASSEMBLY)
19
MAIN CBA
SIF
N-A-OUT
WF8
1
TP753 A-OUT(R)
TP754 A-OUT(L)
IC301
(AUDIO PROCESS) 76
4
EQ AMP
SP/LP-ON
3
1 2
100
ALC
R
MOD-A
A-OUT (R)
A-OUT (L)
A-IN (L)
A-IN (R)
A-IN (L)-F
A-IN (R)-F
N-A-IN
LINE AMP
P
MUTE
96
TO Hi-Fi AUDIO BLOCK
AUDIO HEAD
AUDIO ERASE HEAD
FULL ERASE HEAD
AC HEAD ASSEMBLY
FE HEAD
CN287 A-PB/REC 4 A-COM 3 AE-H 1 AE-H 2
CN504 7 A-PB/REC 6 A-COM 4 AE-H 5 AE-H/FE-H
CN501 1 FE-H 2 FE-H-GND
Q422
BIAS OSC
P-ON+5V
Q423 (PB=ON)
Q425
Q424 (PB=ON)
Q421
SWITCHING D-REC OFF
P-ON+5V
99
AUTO BIAS
6
7
REC AMP
D-REC-H
11 12
1-8-5 1-8-6
REC/EE/PB
16
98
D-PB-H
A-MUTE-H
D-REC-H
FROM SERVO/SYSTEM CONTROL BLOCK

Hi-Fi Audio Block Diagram

SIF
IC451 (MTS/ SAP/ Hi-Fi AUDIO PROCESS/ Hi-Fi HEAD AMP)
NOISE DET
57
SIF DEMOD
SAP FILTER
STEREO FILTER
PILOT DET
SAP DEMOD
PILOT CANCEL
L-R DEMOD
MAIN CBA
ST/SAP SW
DC
dBX DEC
MATRIX
SERIAL DATA DECODER
RIPPLE FILTER
REC-AUDIO SIGNALPB-AUDIO SIGNAL Mode : SP/REC
37 38 39
54
P-ON+9V
Hi-Fi-CS
Hi-Fi-DATA
Hi-Fi-CLK
TO SERVO/ SYSTEM CONTROL BLOCK
TO AUDIO BLOCK
A-IN(R) A-IN(R)-F
N-A-OUT
A-IN(L) A-IN(L)-F
69 71
STEREO PLL
R-CH PNR
R-CH INSEL
6
7 9
NOR SW
L-CH INSEL
48 47
13 14
P
R
SW NOISE
LIM DEV
COMP
VCO
HOLD PULSE
NOISE DET
LPF
MATRIX
R-CH BPF
OUTPUT SELECT
COMP
ALC
BO DET
MUTE
ENV DET
MODE OUT
51 23
80
78
77
40 49
26
ST/SAP-MODE
NORMAL-H
4
2
1
N-A-IN
A-OUT (L)
MOD-A
A-OUT (R)
Hi-Fi-H-SW
A-MUTE-H
TO SERVO/SYSTEM CONTROL BLOCK
TO AUDIO BLOCK
TO SERVO/SYSTEM CONTROL BLOCK
CYLINDER ASSEMBLY
LPF
L-CH BPF
AGC
AGC DET
31 30
R
L
24
27
CN251
Hi-Fi-A(R) 7 Hi-Fi-COM 8 Hi-Fi-A(L) 9
Hi-Fi AUDIO (R) HEAD
Hi-Fi AUDIO (L) HEAD
L-CH PNR
R
P
LIM DEV
SW NOISE
VCO
COMP
1-8-7 1-8-8

Power Supply Block Diagram

NOTE : The voltage for parts in hot circuit is measured using hot GND as a common terminal.
F
A V
AC001
F001 1A 250V
L001
CHOKE
COIL
D001 - D004
BRIDGE
RECTIFIER
F
A V
CAUTION
FOR CONTINUED PROTECTION AGAINST FIRE HAZARD, REPLACE ONLY WITH THE SAME TYPE FUSE. ATTENTION : POUR UNE PROTECTION CONTINUE LES RISQES D'INCELE N'UTILISER QUE DES FUSIBLE DE MEMO TYPE.
RISK OF FIRE
"This symbol means fast operating fuse." "Ce symbole reprèsente un fusible à fusion rapide."
Q001
-REPLACE FUSE AS MARKED.
T001
2
4
11
12
13
14
Q052
CAUTION !
Fixed voltage power supply circuit is used in this unit. If Main Fuse (F001) is blown, check to see that all components in the power supply circuit are not defective before you connect the AC plug to the AC power supply. Otherwise it may cause some components in the power supply circuit to fail.
AL+12V AL+44V AL+12V P-ON-L P-ON+9V TIMER+5V AL+5V P-ON+5V P-DOWN-L AL+15.5V/+12V C-POW-SW
Q055
HOT
Q029
SWITCHING
CONTROL
Q002
7
6
IC001
ERROR VOLTAGE DET
4
15
Q060
16
17
18
1
23
Q061
Q062
Q056
(SHUNT REGULATOR)
Q031
REG
COLD
1-8-9 1-8-10
MAIN CBA

FUNCTION INDICATOR SYMBOLS

Power Supply Trouble Shooting Guide

Note:
The following symbols will appear on the indicator panel to indicate the current mode or operation of the VCR. On-Screen modes will also be momentarily displayed on the TV screen when you press the operation buttons.

Display panel

LED MODE INDICATOR ACTIVE
CASSETTE "IN" CASSETTE "OUT"
VCR/TV VCR MODE VCR/TV TV MODE
CLOCK " 88:88 "
POWER ON " PWR. " ON REC " REC " ON REC PAUSE " REC " Blinks at 0.8Hz interval T-REC, OTR " " ON
When reel and capstan mechanism is not functioning correctly
When tape loading mechanism is not func­tioning correctly
When cassette loading mechanism is not functioning correctly
When the drum is not working properly " "
S-INH condition All modes Blinks at 0.8Hz interval
" " " "
" VCR " " VCR "
" PM "
" " " 1 "
" " " 2 "
" " " 3 "
" 4 "
ON OFF
ON OFF
ON ON/OFF
(T-REC OFF, T-REC incomplete Blinks at 0.8Hz interval)
Blinks at 0.8Hz interval
Blinks at 0.8Hz interval
Blinks at 0.8Hz interval
Blinks at 0.8Hz interval
It is highly recommended that a variable isolation transformer which can monitor current be used. (Alternatively a variable AC source which monitors current will do). Read directions below before power is added!
Repair method
CHECK
Connect unit to the isolation trans­former and slowly increase the AC sup­ply while monitoring the current, if it draws too much current (Be ware fuse is rated for 1.0 amps), then turn off supply and do repair method #1.
NO
Check whether the primary rectifying DC of the Switching power supply has an output. (Reading should be about 168V.)
YES
With the primary DC working check the secondary 5V.
YES
Are the 40V, 12V, -30V, 5V, 15V and filaments lines higher than normal?
NO
Although the secondary 5V is working, are any of the other voltages higher than normal (40V, 12V, -30V, 15V and filament voltages)?
NO
There is no problem on the SW power supply.
YES
NO
NO
YES
YES
#1
#2
#3
#4
#5
Repair method #1
(Power must be off) Short circuit in the secondary side. check diode D013
and {(FIP display model only: D012, D014, D015, D016 and D017) or (LED display model only: D014, D015 and D016)}, switching FET (Q001), control transistor (Q002), diode (D006), and resistor (R014) replace as necessary.
Disconnect 40V diode (D013), 15V diode (D014), 12V diode (D015), 5V diode (D016) and {FIP display model only: -30V diode (D012) and filament voltage diode (D017)}Check the load continuity of 40V line, 15V line, 12V line, 5V line, -30V line and filament voltage line through a tester (resistance range).
If the tester indicates a lower resistance value around 0 ohm, the line is short-circuited.
Before repairing the switching power supply, find out the short-circuited area of such line and repair it.
If the tester does not indicate any low resistance value (around 0 ohm), no load is short-circuited and there is no problem.
2] Check for any defective parts while the secondary rectifying diodes are disconnected (D013, D014, D015, D016 and {FIP display model only: D012 and D017)} perform a diode check in both forward and reverse directions through a tester.
3] Remove the following components and check for defects: snubber diode (D051), switching FET (Q001), source resistor (R014), control transistor (Q002).
Repair method #2
Check the fuse 1.0A (F001), primary rectifying diodes (D001-D004) as possible problems. Remove the above mentioned parts and check them. The circuit which turns on switching FET (Q001) may be regarded as a possible cause, even if the load at the secondary side is shorted, it can’t be detected because switching FET (Q001) isn’t operating. Perform check according to the step 1 and 2 of repair method #1 and check the following parts:
(Remove the part from PCB) Switching FET (Q001), source resistor (R014), gate
resistor (R008) and start resistor (R004 and R005).
Repair method #3
A circuit to turn on switching FET (Q001) may not work and this may be regarded as a cause of trouble. Even if the load at the secondary side is short-circuited, it cannot be detected because switching FET (Q001) does not turn on. Therefore, perform check according to the steps 1] and 2] of the repair method #1 and execute the under-mentioned parts breakage check.
(Remove the part from PCB.) switching FET (Q001), source resistor (R014), control
transistor (Q002), gate resistor (R008) and start resistor (R004 and R005).
Repair method #4
The feedback circuit which is monitored by the output of voltage may not work and this may be regarded as a possible cause, remove control transistor Q002 and check for defects. More over, a photo coupler (IC001) and transistor (Q031) may be defective, replace any defective parts with factory originals.
Repair method #5
If the output voltage of the secondary side is slightly high, the line load may be in the "OPEN" state and this may be regarded as a cause of trouble. If there is no output voltage on the secondary side, the rectifying diodes (D013), (D014), (D015) and {FIP display model only only: (D012) and (D017)} may be defective.
1-8-11
1-8-12

SCHEMATIC DIAGRAMS / CBA’S AND TEST POINTS

Standard Notes

Warning
Many electrical and mechanical parts in this chassis have special characteristics. These characteristics often pass unnoticed and the protection afforded by them cannot necessarily be obtained by using replace­ment components rated for higher voltage, wattage, etc. Replacement parts that have these special safety char­acteristics are identified in this manual and its supple­ments; electrical components having such features are identified by the mark " #" in the schematic diagram and the parts list. Before replacing any of these compo­nents, read the parts list in this manual carefully. The use of substitute replacement parts that do not have the same safety characteristics as specified in the parts list may create shock, fire, or other hazards.

Capacitor Temperature Markings

Mark
Capacity
change rate
(B) ±10% 20°C -25~+85°C (F) +30 -80% 20°C -25~+85°C
(SR) ±15% 20°C -25~+85°C
(Z) +30 -80% 20°C -10~+70°C
Standard
temperature
Temperature
range
Note:
1.Do not use the part number shown on these draw­ings for ordering. The correct part number is shown in the parts list, and may be slightly different or amended since these drawings were prepared.
2.All voltages are DC voltages unless otherwise speci­fied.

Values in schematic diagrams

The values, dielectric strength ( power capacitance ) and tolerances of the resistors ( excluding variable resistors ) and capacitors are indicated in the schematic diagrams using abbreviations.
[ Resistors ]
Item Indication
Value
Power
capacitance
No indication...........................
K............................................k
M..........................................M
No indication............1/4W,1/6W
All capacitances other than the above are indicated in schematic diagrams.
Capacitors and transistors are represented by the fol­lowing symbols.
CBA Symbols
(Top View) (Bottom View)
(Bottom View)
E C B
(Top View)
E C B
(Top View)
E C B
Schematic Diagram Symbols
+
Electrolytic Capacitor
Transistor or Digital Transistor
(Top View)
NPN Transistor
NPN Digital Transistor
Digital Transistor
E C B
(Top View)
E C B
PNP Transistor
PNP Digital Transistor
[ Capacitors ]
Item Indication
Value
No indication...........................µF
P..............................................pF
No indication...........................50V
Dielectric
strength
All dielectric strengths other than 50V are indicated in schematic diagrams.
[ Coils ]
Item Indication
Value
µ...............................................µH
m.............................................mH
1-9-1
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