akira VCR-S608 User manual

Video Cassette Recorder
Service Manual

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Model No.: VCR-S608
Version: 1.0
MODEL:
VCR-S608

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Model No.: VCR-S608
Version: 1.0
CONTENTS
IMPORTANT SERVICE GUIDE............................................................................................................. 4
PRECAUTIONS ...................................................................................................................................... 6
ALIGNMENT & ADJUSTMENT ........................................................................................................... 9
CABINET ASSEMBLY......................................................................................................................... 21
ELECTRCAL PART LIST..................................................................................................................... 27
BLOCK DIAGRAM .............................................................................................................................. 43
S.M.P.S. .................................................................................................................................................. 46
POWER DRIVE..................................................................................................................................... 47
TIMER ................................................................................................................................................... 48
SYSTEM CONTROL/ SERVO /OSD.................................................................................................... 49
AUDIO /VIDEO..................................................................................................................................... 50
HI-FI (OPTION)..................................................................................................................................... 51
TM.......................................................................................................................................................... 52
SECAM (OPTIONAL)........................................................................................................................... 53
A2 /NICAM............................................................................................................................................ 54
INPUT-OUTPUT ................................................................................................................................... 55
SUB ........................................................................................................................................................ 56

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Model No.: VCR-S608
Version: 1.0
IMPORTANT SERVICE GUIDE
MODE SWITCH (PROGRAM SWITCH) ASSEMBLY POINT
1) When installing the ass’y deck on the Main PCB, be sure to align the assembly point of mode
switch.
HOW TO EJECT THE CASSETTE TAPE
(If the tape is stuck in the unit)
1 Turn the Gear Worm clockwise in the direction of arrow with screwdriver. (See Fig. 2)
(Other method; Remove the screw of Motor Load Ass’y, Separate the Motor Load Ass’y)
2 When Slider S, T are approaches the unloading position, rotate holder Clutch counter clockwise
after inserting screwdriver in the frame’s bottom hole in order to wind the unwound tape. (Refer to
Fig. 3)
3 (If you rotate Gear Worm continuously when tape is unwinding, you may cause tape contamination
by grease and tape damage. Be sure to wind the unwound tape with the unit in the horizontal
position.)
4 Rotate Gear Worm clockwise using a screwdriver until the mecha is in the eject state. Remove the
tape. (Refer to Fig. 2)

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Model No.: VCR-S608
Version: 1.0

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Model No.: VCR-S608
Version: 1.0
PRECAUTIONS
1. Be sure that all of the built-in protective devices are replaced. Restore any missing protective
shields.
2. When reinstalling the chassis and its assemblies, be sure to restore all protective devices, including:
control knobs and compartment covers.
3. Make sure that there are no cabinet openings through which people--particularly children --might
insert fingers and contact dangerous voltages. Such openings include the spacing between the
picture tube and the cabinet mask, excessively wide cabinet ventilation slots, and improperly fitted
back covers.
If the measured resistance is less than 1.0 megohm or greater than 5.2 megohms, an abnormality
exists that must be corrected before the unit is returned to the customer.
4 Leakage Current Hot Check (See Fig. 1-1):
Warning : Do not use an isolation transformer during this test. Use a leakage current tester or a
metering system that complies with American National Standards Institute (ANSI C101.1, Leakage
Current for Appliances), and Underwriters Laboratories (UL Publication UL1410, 59.7).
5 With the unit completely reassembled, plug the AC line cord directly the power outlet. With the
unit’s AC switch first in the ON position and then OFF, measure the current between a known earth
ground (metal water pipe, conduit, etc.) and all exposed metal parts, including: antennas, handle
brackets, metal cabinets, screw heads and control shafts. The current measured should not exceed
0.5 milliamp. Reverse the power-plug prongs in the AC outlet and repeat the test.
6 X-ray Limits:
The picture tube is designed to prohibit X-ray emissions. To ensure continued X-ray protection,
replace the picture tube only with one that is the same type as the original.
7 Antenna Cold Check:
With the unit’s AC plug disconnected from the AC source, connect an electrical jumper across the
two AC prongs. Connect one lead of the ohmmeter to an AC prong. Connect the other lead to the
coaxial connector.
8 High Voltage Limit:
High voltage must be measured each time servicing is done on the B+, horizontal deflection or high
voltage circuits. Heed the high voltage limits. These include the X-ray protection Specifications
Label, and the Product Safety and X-ray Warning Note on the service data schematic.
9. Some semiconductor (“solid state”) devices are easily damaged by static electricity. Such
components are called Electrostatically Sensitive Devices (ESDs); examples include integrated
circuits and some field-effect transistors. The following techniques will reduce the occurrence of
component damage caused by static electricity.
10. Immediately before handling any semiconductor components or assemblies, drain the electrostatic
charge from your body by touching a known earth ground. Alternatively, wear a discharging
Wrist-strap device. (Be sure to remove it prior to applying power--this is an electric shock
precaution.)

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Model No.: VCR-S608
Version: 1.0
11. High voltage is maintained within specified limits by close-tolerance, safety-related components and
adjustments. If the high voltage exceeds the specified limits, check each of the special components.
12. Design Alteration Warning:
Never alter or add to the mechanical or electrical design of this unit. Example: Do not add auxiliary
audio or video connectors. Such alterations might create a safety hazard. Also, any design changes or
additions will void the manufacturer’s warranty.
13. Hot Chassis Warning:
Some TV receiver chassis are electrically connected directly to one conductor of the AC power cord.
If an isolation transformer is not used, these units may be safely serviced only if the AC power plug
is inserted so that the chassis is connected to the ground side of the AC source.
To confirm that the AC power plug is inserted correctly, do the following: Using an AC voltmeter,
measure the voltage between the chassis and a known earth ground. If the reading is greater than
1.0V, remove the AC power plug, reverse its polarity and reinsert. Re-measure the voltage between
the chassis and ground.
14. Some TV chassis are designed to operate with 85 volts AC between chassis and ground, regardless
of the AC plug polarity. These units can be safely serviced only if an isolation transformer inserted
between the receiver and the power source.
15 Never defeat any of the B+ voltage interlocks. Do not apply AC power to the unit (or any of its
assemblies) unless all solid-state heat sinks are correctly installed.
16 Always connect a test instrument’s ground lead to the instrument chassis ground before connecting
the positive lead; always remove the instrument’s ground lead last.

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Model No.: VCR-S608
Version: 1.0
17 Observe the original lead dress, especially near the following areas: Antenna wiring, sharp edges,
and especially the AC and high voltage power supplies. Always inspect for pinched, out of place, or
frayed wiring. Do not change the spacing between components and the printed circuit board. Check
the AC power cord for damage. Make sure that leads and components do not touch thermally hot
parts.
18 Picture Tube Implosion Warning:
The picture tube in this receiver employs “integral implosion” protection. To ensure continued
implosion protection, make sure that the replacement picture tube is the same as the original.
19 Do not remove, install or handle the picture tube without first putting on shatterproof goggles
equipped with side shields. Never handle the picture tube by its neck. Some “in-line” picture tubes
are equipped with a permanently attached deflection yoke; do not try to remove such “permanently
attached” yokes from the picture tube.
20 Product Safety Notice:
Some electrical and mechanical parts have special safety-related characteristics which might not be
obvious from visual inspection. These safety features and the protection they give might be lost if the
replacement component differs from the original--even if the replacement is rated for higher voltage,
wattage, etc.
Components that are critical for safety are indicated in the circuit diagram by shading, ( or ).
Use replacement components that have the same ratings, especially for flame resistance and
dielectric strength specifications. A replacement part that does not have the same safety
characteristics as the original might create shock, fire or other hazards.

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Model No.: VCR-S608
Version: 1.0
ALIGNMENT AND ADJUSTMENT
Reference
1 X-Point (Tracking center) adjustment, “Head switching adjustment” and “NVRAM option setting”
can be adjusted with remote control.
2 When replacing the Main PCB Micom (IC601) and NVRAM (IC605 ; EEPROM) be sure to adjust
the “Head switching adjustment” and “NVRAM option setting”.
3 When replacing the cylinder ass’y, be sure to adjust the “X-Point” and “Head switching
adjustment”.
4 Among Samsung VCR remote control used for adjustment as an accessory, only the remote control
that has figures buttons (0 ~ 9) is available for all adjustment regardless of chassis.
5 How to adjust.
a. Momently short-circuit th test point on Main PCB with pincers to set the adjustment mode.
b. If the corresponding adjustment button is pressed, the adjustment is performed automatically.
c. When the adjustment is completed, be sure to turn the power off.

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Model No.: VCR-S608
Version: 1.0
Location of adjustment button of remote control

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Model No.: VCR-S608
Version: 1.0
Location for adjustment mode setting

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Model No.: VCR-S608
Version: 1.0
Head Switching Point Adjustment
1) Playback the alignment tape.
2) Momently short-circuit the test point on Main PCB with pincers to set the adjustment mode.
(See Fig. 2-2)
3) Press the “SPEED” buttons; remote control adjustment operates automatically. (See Fig. 2-1)
4) Turn the Power off.
NVRAM Option Setting
1. NVRAM Option is adjusted in the factory.
2. In case Main PCB Micom (IC601 and NVRAM (IC605; EEPROM) are replaced, be sure to set
the corresponding option number of the required model. (If the option is not set, the unit will
not operate).
1) Momently short-circuit the test point on Main PCB with pincers to set the adjustment mode.
(See Fig. 2-2)
2) Press the “MENU” button on the remote control. The option setting appears. (See Fig. 2-3)
3) Select the option number (See table 2-1) of corresponding model with “ ◄, ►, ▲, ▼” buttons
on the remote control.
4) After selecting the option number is completed, press the “▲” button of remote control.
(If “▲” button is pressed, the selected number is changes color; See Fig. 2-4)
5) Press the “ENTER” button of remote control again to store the option number.
6) Turn the Power off.
Model Option numbers
VCR-608(S) 6, 7, 8, 9, 10, 12, 15, 20, 22, 25, 27, 29, 35, 38, 42, 47, 55, 56, 57, 61, 64

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Model No.: VCR-S608
Version: 1.0
VCR MECHANICAL ADJUSTMENT
Tape Transport System and Adjustment Locations
The tape transport system has been adjusted precisely in the factory. Alignment is not necessary except
for the following:
1. Noise observed on the screen.
2. Tape damage.
3. Parts replacement in the tape transport system.
Lower flange height of tape guide is used as the reference for the transport adjustment.
To maintain the height of the tape guide and prevent damage, do not apply excessive force onto the main
base.
Fig. 2-5 Location of Tape Transport Adjustment
CYLINDER ASS'Y
TAKE UP REEL DISK
#8 GUIDE POST
#9 GUIDE POST
SUPPLY REEL DISK
CAPSTAN
PINCH ROLLER
GUIDE ROLLER "T"
GUIDE ROLLER "S"
FULL ERASE HEAD
#3 GUIDE POST
TENSION POST
HEIGHT SCREW
TILT SCREW
X - POSITION
ADJUST SILT
AZIMUTH SCREW

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Model No.: VCR-S608
Version: 1.0
Tape Transport System Adjustment
When parts are replaced, perform the required adjustments by referring to procedures for the tape
transport system. If there are any changes to the tape path, first run a T-120 tape and make sure excessive
tape wrinkle does not occur at the tape guides.
 If tape wrinkle is observed at the guide roller S, T, turn the guide roller S, T until wrinkle disappears.
 If the tape wrinkle is still observed at the tape guide, perform the tilt adjustment of the ACE head.
(1) ACE Head Assembly Adjustment
a. ACE HEAD HEIGHT ADJUSTMENT
1. Run the alignment tape (Color bar) in the playback mode.
2. Observe surface of the audio head using a dental mirror.
3. Turn screw (C) clockwise or counterclockwise until the gap of lower tape edge and the lower
edge of the control head is about 0.25mm. (Refer to Fig. 2-7 and 2-8)
Fig. 2-6 Tape Travel Diagram
POST TENSION
MAIN BASE
FE HEAD CYLINDER ASS'Y PINCH ROLLER
GUIDE ROLLER "S" GUIDE ROLLER "T"
#8 GUIDE POST #9 GUIDE POST
CAPSTAN SHAFT
ACE HEAD
#3 GUIDE POST
2-5
Fig. 2-7 Location of ACE Head Adjustment Screw
Fig. 2-8 ACE Head Height Adjustment
SCREW (A)
TLIT ADJUST
X-POSITION
ADJUSTING SLIT
SCREW (C)
HEIGHT ADJUST
SCREW (D)
X-POSITION LOCKING
SCREW (B)
AZIMUTH ADJUST

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Model No.: VCR-S608
Version: 1.0
b. ACE HEAD TILT ADJUSTMENT
1. Playback a blank tape and observe the position of the tape at the lower flange of tape guide.
2. Confirm that there is no curl or wrinkle at the lower flange of tape guide as shown in Fig. 2-9
(B).
3. If a curl or wrinkle of the tape occurs, slightly turn the screw (A) tilt adjust on the ACE head
ass’y.
4. Reconfirm the ACE head height.
Fig. 2-8 ACE Head Height Adjustment
0 ~ 0 .25 mm
AUDIO HEAD
VIDEO HEAD
CONTROL HEAD
2-6
Fig. 2-9 Tape Guide Check
(A) (B)
(BAD)
WRINKLE
(GOOD)

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Model No.: VCR-S608
Version: 1.0
c. AUDIO AZIMUTH ADJUSTMENT
1. Load alignment tape (Mono scope) and playback the 7KHz signal.
2. Connect channel-1 scope probe to audio output.
3. Adjust screw (B) to achieve maximum audio level. (See Fig. 2-7)
d. ACE HEAD POSITION (X-POINT) ADJUSTMENT
1. Playback the alignment tape (Color bar)
2. Intermittently short-circuit the two Test Points on Main PCB. (See Fig. 2-2)
3. Press the “5” remote control button, then adjustment is operates automatically. (See Fig. 2-1)
4. Connect the CH-1 probe to “Envelope” the CH-2 probe to “H’D switching pulse” and then
trigger to CH-1.
5. Insert the (-) driver into the X-Point adjustment hole and adjust it so that envelope waveform is
maximum.
Test point :
TP301 (Envelope)
TP302 (Audio output)
TP602 (H’D S/W -Trigger)
Fig. 2-10 Location of Test point (Main PCB-Top View)
AUDIO OUTPUT
HEAD SWITCHING
ENVELOPE

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Model No.: VCR-S608
Version: 1.0
(2) Linearity adjustment (Guide roller S, T adjustment)
1. Playback the Mono Scope alignment tape (SP mode).
2. Observe the video envelope signal on an oscilloscope (triggered by the video switching pulse).
3. Make sure the video envelope waveform (at its minimum) meets the specification shown in Fig.
2-11.
If it does not, adjust as follows:
Note :
a=Maximum output of the video RF envelope.
b=Minimum output of the video RF envelope at the entrance side.
c=Minimum output of the video RF envelope at the center point.
d=Maximum output of the video RF envelope at the exit side.
4. If the section A in Fig. 2-12 does not meet the specification, adjust the guide roller S up or
down.
5. If the section B in Fig. 2-12 does not meet the specification, adjust the guide roller T up or
down.
6. Play back the Mono Scope alignment tape (SP mode).
7. Connect an oscilloscope CH-1 to the “Envelope” and CH-2 to the “H’D SW Pulse” for
triggering.
8. Turn the guide roller heads with a flat head ( ) driver to obtain a flat video RF envelope as
shown in Fig. 2-13.
2-8
Fig. 2-11 Envelope Waveform Adjustment
a
a b c d
c,b,d/a 63%
bcd

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Model No.: VCR-S608
Version: 1.0
Fig. 2-13 Guide Roller S, T Height Adjustment
IDEAL ENVELOPE
SHEIGHTTOOHIGH SHEIGHTTOOLOW THEIGHTTOOHIGH THEIGHTTOOLOW
GUIDE ROLLER S GUIDE ROLLER T
Fig. 2-12 Adjustment Points
AB
A B
H'D SWITCHING PULSE
ENVELOPE

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Model No.: VCR-S608
Version: 1.0
(3) Check Transitional Operation from RPS to Play
Check transition from RPS mode to play mode : Using a pre-recorded SP tape, make sure the entry side
of envelope comes to an appropriate steady state within 3 seconds (as shown in Fig. 2-14).
If the envelope waveform does not reach specified peak-to peak amplitude within 3 seconds, adjust as
follows :
1. Make sure there is no gap between the supply roller lower flange and the tape.
2. If there is a gap, adjust the supply guide roller again.
3. Change operation mode from the RPS to the play mode (again) and make sure the entry side of
envelope rises within 3 seconds.
(4) Envelope Check
1. Make recordings on T-120 (E-120) and T-160 (E-180) tape.
Make sure the playback output envelope meets the specification as shown in Fig. 2-15.
2. Play back a self recorded tape (recording made on the unit using with T-120 (E-120).
The video envelope should meet the specification as shown in Fig. 2-15.
In SP mode, (A) should equal (B).
If the head gap is wide, upper cylinder should be checked.
ENTRANCE SIDE ENVELOPE
Fig. 2-14 Video Envelope Rising when Operation mode Changes from RPS to Play Mode
A B
Fig. 2-15 Envelope Input and Output Level

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Model No.: VCR-S608
Version: 1.0
(5) Tape Wrinkle Check
1. Run the T-160 (E-180) tape in the playback, FPS, RPS and Pause modes and observe tape
wrinkle at
2. each guide.
3. If excessive tape wrinkle is observed, perform the following adjustments in Playback mode :
 Tape wrinkle at the guide roller S, T section : Linearity adjustment.
 Tape wrinkle at tape guide flange : ACE head assembly coarse adjustment.
Reel Torque
1. The rotation of the capstan motor causes the holder clutch ass’y to rotate through the belt pulley.
2. The spring wrap PLAY/REV of holder clutch ass’y drives the disk reel S, T through gear idler
by rotation of gear center ass’y.
3. Brake is operated by slider cam at FF/REW mode.
4. Transportation of accurate driving force is done by gears. (Gear Center Ass’y)
Note : If the specification does not meet the followings specifications, replace the holder clutch ass’y and
then recheck.
<Table 2-2>
MODE TORQUE g/cm GAUGE
PB 42 ± 11 Cassette Torquemeter
RPS 145 ± 30 Cassette Torquemeter