SHARP XA-705, XA-710, XA-720 Service Manual

XA-705

1 XA-71 O,XA-720

. -: SHARF’

XA-705

XA-710

@mq$3q I

7rw

XA-720

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SERVICE MANUAL

S78T6XA-705//

/vus/ PROFESSIONAL

VIDEO CASSETT

XA-705

MODELS XA-710, XA-720

In the interests of user-safety (Required by safety regulations in some countries) the set should be restored to its original. condition and only parts identical to those specified be used.

SERIES

E RECORDER

Page

1. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

I-1 FEATURES . . . . . . . ..‘....................................... 4

1-2 SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

l-3 LOCATION OF MAJOR COMPONENTS

AND CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2. DISASSEMBLY AND REASSEMBLY m........,.... 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 . . . . . . . . . . . . . . . . . . . . . ..~......................................

4. ADJUSTMENT, REPLACEMENT AND

ASSEMBLY OF MECHANICAL UNITS . . . . . . . . . . 11

4-l MECHANISM CONFIRMATION

ADJUSTMENT JIG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

5. ELECTRICAL ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . 30

5-I ADJUSTMENT OF HEAD SWITCHING

POINT

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..*.......................

5-2 ADJUSTMENT OF FV (False Vertical Sync)

OF STILL PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5-3 CHECKING OF OFF TRACK . . . . . . . . . . . . . . . . 31

5-4 ADJUSTMENT OF SIF-INPUT LEVEL . . . . 32

5-5 ADJUSTMENT OF FILTER . . . . . ..e.............. 32

5-6 ADJUSTMENT OF STEREO VCO . . . . . . . . . . . 32

5-7 ADJUSTMENT OF STEREO

SEPARATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6. MECHANISM OPERATION FLOWCHART

AND TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . 33

7. TROUBLESHOOTING . . . . . . . . ..*........................

8. BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9. SCHEMATIC DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

lO.PRINTED WIRING BOARD ASSEMBLIES . . . . 80

11 .PARTS LIST

12.PACKING OF THE SET

. . . . . . . . . . . . . . . . ..*.................................

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page

39 53 62

103

SHARP CORPORATION

This document has been published to be used for after sales service only. The contents are subject to change without notice.

XA-705 XA-71 O,XA-720

IMPORTANT SERVICE NOTES

BEFORE RETURNING THE VIDEO CASSETTE RECORDER

Before returning thevideo cassette recorder to the 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 the chassis and other metal parts in the video cassette recorder.

2. Inspect all protective devices such as non-metallic control knobs, insulation materials, cabinet backs, adjustment and compartment covers or shields, isolation resistor/capacitor networks, mechanical insulators and etc.

3. To be sure that no shock hazard exists, check for current in the following manner.

l Plug the AC line cord directly into a 120 volt AC outlet

(Do not use an isolation transformer for this test).

l Using two clip leads, connect a 1.5k ohm, 10 watt

resistor paralleled by a 0.15yF capacitor in series with all exposed metal cabinet parts and a known earth ground, such as a water pipe or conduit.

l Use an SSVM or VOM with 1000 ohm per volt, or

higher, sensitivity or measure the AC voltage drop TO EXPOSED across the resistor. (See Diagram)

l Move the resistor connection to earth exposed metal

part having a return path to the chassis (antenna,

metal cabinet, screw heads, knobs, control shafts and etc.) and measure the AC voltage drop across the resistor. Reverse the AC plug on the set and repeat AC voltaae measurements for each exposed part. Any readhg of 0.45V rms (this corresponds to 0.3mA rms AC.) or more is excessive and indicates a potential shock hazard which must be corrected before returning the video cassette recorder to the owner.

METAL PARTS

SSVM

( 9ACSCALE 9 \

’ m%t?m

WARNING :TO REDUCETHE RISKOF FIRE OR ELEC-

TRIC SHOCK, DO NOT EXPOSE THIS AP-

PLIANCE TO RAIN OR MOISTURE.

RISK OF ELECTRIC SHOCK

A-==-

CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK. DO

1 0

CAUTION:

1.6A 125v

NOT REMOVE COVER. NO USER-SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.

This symbol warns the user of uninsulated voltage within the unit that can cause dangerous electric shocks.

This symbol alerts the user that there are important operating and maintenance instructions in the literature accompanying this unit.

This symbol mark means fast operating fuse.

For continued protection against risk of fire, replace

only with same type fuse F901 (1.6A, 125V).

DO NOT OPEN

1 0

XA-705 XA-71 O,XA-720

PRECAUTIONS IN PART REPLACEMENT

When servicing the unit with power on, be carefwl 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.

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.

Photocoupler: IC901

Refer to the symbol on the PWB and the anode marking of the part.

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.

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.

XA-705 XA-71 O,XA-720

1 l GENERAL INFORMATION

l-1 FEATURES

Common Features

8 Hours of Recording / Playback (T-160)

181 ch Cable Ready With Frequency Synthesizer Tuner

CM Skip Search

Automatic Playback Function

Blue Screen 81 On Screen Setup Programming Function

Full Loading System

Simple Recording Timer

Tamper Proof Function

Automatic Tracking System

3-Language OSD

Sharp Super Picture

Instant Replay

Universal R/C

EZ Set Up

Automatic Daylight Saving-Time (DST) Adjustment

Quasi S-VHS Playback

1 Hour Back-up

1-2 SPECIFICATIONS

1) Recording system Format:

Luminance Signal:

Chroma Signal:

Color System:

Number of Video Head:

Tape Speed:

2) Video signal

Input Level:

Output Level:

Signal to Noise Ratio:

Horizontal Resolution:

3) Audio signal

Input Level:

Output Level:

Frequency Response:

Signal to Noise Ratio:

Hi-Fi Dynamic Range:

Wow and Flutter:

4) Receiving channel

CATV:

Antenna Input Impedance:

5) Miscellaneous

Fast forward /Rewind Time:

Power Source:

Power Consumption:

Allowable Ambient Temperature:

Operating Humidity:

Dimensions:

Weight:

Accessories Included:

VHS NTSC Standard

FM recording Low frequency converted direct recording NTSC

4 PCS.

(SP) 33.35 mm/set (LP) 16.67 mm/set (playback only) (EP) 11.12 mm/set

0.5 - 2.0 Vp-p, 75 ohm unbalanced 1 .O Vp-p, 75 ohm unbalanced 45dB Min. (SP mode) 220 lines Min. (SP mode)

- 8 dBs (309 mVrms, 47k ohm Min.)

- 8 dBs (309 mVrms, 1 k ohm Max.) 80Hz - IOkHz (Linear), 20Hz - 20kHz (Hi-Fi) (at SP mode) 43dB (Linear) (at SP mode) 90dB (XA-720)

0.005% max. (XA-720)

VHF:

ch. 2 - 13

UHF:

ch. 14 - 69 ch. A8, A5 - W +84 75 ohm

Approximate 1 minute with T-120 cassette

120 V AC, 60 Hz 20 W at 12OV AC, 60Hz 5 to 40°C (41 to 104°F)

Less than 80% RH XA-705: 360 (W) x 92 (H) x 269 (D) mm(14-3/16 x 3-5/8 x 10-I 9/32 inch) XA-710: 360 (W) x 92 (H) x 276 (D) mm(l4-3/16 x 3-5/8 x 1 O-7/8 inch)

XA-720: 360 (W) x 92 (H) x 264 (D) mm(14-3/16 x 3-5/8 x lo-13/32 inch)

2.8 kg (6.0 Ibs)

75 ohm Coaxial Cable, Opetarion Manual, Timer Setting Card,

Infrared R/C Unit, Dry Battery (3 PCS.)

Only for XA-710, XA-720

l Cable Box Control l Automatic Head Cleaning l VCR Plus + Programming System

Only for XA-720

l Universal R/C with Light up l Viewcam Dubbing

Note: Specifications are subject to change without notice.

w” al

I-

-I

Remote Control Mode Select

buttons (VCR, TV, CABLE/SAT )

l Used to selecl the component (VCR.

Remote Control

TV CABLE BOX/SAT ) to be opera!ed

ON SCREEN button

DISPLAY button

VOL (VOLUME) O/O buttons

A/V buttons

CH (CHANNEL)

VCR PLUS+ button

SET button

ZERO BACK button

SKIP SEARCH button

REPLAY button

n controls

:k/Recording)

TAMPER PROOF button

*lOO. ENT /AM/PM button

INPUT button

*FF button

PAUSE/STILL button

*STOP button

TAPE SPEED button

O/O buttons (SLOW @X3.

DPSS &/a,)

AUTO REPEAT button

Only for XA-720

Q button

Only for XA-720

Symbol Function Statu

l Press the button to Illumlna:e the

VIEWCAM DUBBING button

backlll bultons (Indlcatecl with the

*mark) for 10 seconds

_ 1 I

Only for XA-720

If the 0 button IS pressed whrle the backlit buttons are Illumtnated. they WIII remarn illumlnated for an adddtonal 10 seconds

Inserting the Batteries

Make sure that the battenes have been properly Installed first. Fit two batteries type

“AA”. If the remote control stops worktng. fit new batteries.

remote control

INoTE)

On/y for XA-720

l The operating life of the batteries WIII shorten If the “Backlit” function IS frequently used

and Digital Satellite Receiver must be re-entered.

l After changing the batteries in the remote control, the code settings for the TV, cable box

Ensure the battenes are fitted correctly, matching the polarltles (O/e) indicated in the

l uo nor suoject the remote control to shock, water or excessive humidity

l The remote control may not function If the VCR sensor IS In direct sunllght or any other strong light

l Incorrect use of battenes may cause them to leak or burst Read the battery warnings and use the batteries properly

l Do not mix old and new battenes or mix brands 111 use

before re-tnstalling them

l Remove the batterlcs If the remote control wll not be operated for an extended penod of time

_ I‘ AL-^ ____L

- II LII~: relllute control does not function properly when new batteries are Installed. remove the battenes and watt 5 minutes

Cable TV Connections)

(XA-720)

Connection terminals (see Tape Dubbing)

Connectron terminals (see Connecting the VCR and

I I I I I I I

I I I I I

3 tf 4 OUTPUT CHANNEL selector 1 (see Setting the 3 +-+ 4 Output Channel Selector)

a Major Components of Your VCR

[Front]

Cassette compartment (see Playback/Recording)

Basic function controls

(see Playback/Recording)

on the model

l The design may be slightly different depending

INoTE)

Multi-Function Display (explained throughout the operation instructions)

Symbol Function Status Display

Display

Display Symbol Function Status

Function Status

Display Symbol

riimir)

Cable TV Connections)

(XA-710)

VCR enters the operation mode

l The display wtll return to the original mode (counter or clock display) 3 seconds after the

Connection terminals (see Tape Dubbitng)

Connection terminals (see Connecting the VCR and

[Rear]

3 tf 4 OUTPUT CHANNEL selector

(see Setting the 3 t+ 4 Output Channel Selector)

Cable TV Connections)

Connection terminals (see Tape Dubbing)

Connectlon terminals (see Connecting the VCR and

(see Setting the 3 cf 4 Output Channel Selector)

VCR enters the operation mode

l The display WIII return to the orIgInal mode (counter or clock drsplay) 3 seconds after the

m Major Components of Your VCR

[Front]

POWER button-

(When pressed to turn on the VCR. some lndrcators

on the Multi-Function display light up, and the Multl-Functron

display bnghtens When the power IS turned off, the Multl-

Function dlsplaj dims )

[Rear]

XA-705 XA-71 O,XA-720

2. DISASSEMBLY AND REASSEMBLY

24 DISASSEMBLY OF MAJOR BLOCKS

TOP CABINET FRONT PANEL

OPERATION (SHUTTLE JOG) PWB DRUM SHIELD

: Remove 3 screws 0. : Remove shuttle switch knob 0.

Remove 2 screws @ and 7 clips @.

: Remove 1 screw 0. Take it out

of connector @.

: Remove 1 screw @ with drum

shield.

TERMINAL PWB :

VIDEO JACK PWB MECHANISM/ MAIN PWB

Remove 3 screws (XA705/720)/2 screws (XA-710) @I, 1 screw @, 2 clips @J and 2 screws @I (XA-710) with Terminal PWB and

Terminal cover.

Disconnect earth lead and wire

lead.

Remove 2 screws 0 and

disconnect wire lead.

Remove 2 screws a, 1 screw @

and 1 screw @.

Remove 1 screw @I with antenna

terminal cover.

TOP CABINET

MECHANISM/

:,.

FRO

SHUTTLE

2-2 DISASSEMBLING THE MECHANISM/MAIN PWB ASSEMBLY

1. When removing the mechanism from the main PWB.

Remove the antennacover

the antenna cover.

PWB bottom plate 1 screw @.

Remove

Remove the FFC connects the PWB and the mechanism. Take out vertically not damage the adjacent parts.

the

cable (AA, AD, AH) @ which

the mechanism so

1 screw a, and remove

it does

that

MECHANISM CHASSIS

_I_

2. Removing the mechanism and cassette controller.

Remove 2 screws @

the mechanism, and remove the

to troller.

fixing the cassette controller

cassette

con-

XA-705 XA-71 O,XA-720

2-3 Cares when reassembling

INSTALLING THE CASSElTE CONTROLLER

When the cassette controller is installed on the mecha-

nism, the initial setting is essential condition.

There are two initial setting methods, namely electrical

and mechanical.

1. Electrical initial setting

So as to perform initial setting of mechanism execute the

Step 1 of Installation of cassette housing. After ascertaining the return to the initial setting position (*I) install the cassette controller. (Conditions: When mechanism

and PWB have been installed)

Pulley feed gear

mark (*I)

2. Mechanical initial setting

Feed the pulley feed gear of loading motor with screw

driver. After ascertaining the return to the initial set

position (*I) install the cassette controller in the speci-

fied position. (This method is applied only for the mecha-

nism.)

Casecon drive gear

angle of

casse

tte control

INSTALLING THE MECHANISM ON PWB

Lower vertically the mechanism, paying attention to the mechanism edge, and install the mechanism with due care so that the parts are not damaged. So as to fix the mechanism to the main PWB install two housings. (Fit the antenna 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.

END SENSOR

REC TIP SW

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.

AE CONNECTOR

AC CONNECTOR

XA-705 XA-71 O,XA-720

REMOVING AND INSTALLING THE CASSETTE HOUSING

l Removal

1. In the cassette removing mode remove the cassette.

2. Unplug the power cord.

3. Remove in the following numerical order. a) Remove two screws 0. b) Slide and pull up the cassette housing control.

Notes:

When fitting the S/E sensor holder to the cassette controller frame L/R, take care.

Misengagement of teeth of casecon drive gear and

drive angle gear causes malfunction. (The cassette

cannot be set, load and ejection are repeated).

In the case when you use the magnet screw driver,

never approach the magnet driver to the A/C head,

FE head, and drum.

When installing or removing, take care so that the cassette housing control and tool do not contact the guide pin or drum.

After installing the cassette housing control once

perform cassette loading operation.

TO RUN A TAPE WITHOUT THE CASSETTE

HOUSING CONTROL ASSEMBLY

1 .

Remove the full-surface panel.

2 .

Short-circuit TP801.

Plug in the power cord.

3 4:

Turn off the power switch.

(The pole bases move into U.L.position.)

5 .

Open the lid of a cassette tape by hand.

Hold the lid with two pieces of vinyl tape.

6 7:

Set the cassette tape in the mechanism chassis.

Stabilize the cassette tape with a weight (500g) to

prevent floating.

9 . Turn on the power switch.

Perform running test.

Figure 4-I.

0 Reassembly

1. Before installing the cassette housing control, shortcircuit TP801 provided at the center (when facing to the main PWB), press the eject button. The casecon drive gear turns and stops when the positioning mark

. .

appears. Engage two teeth of casecon drive gear

with the three teeth of casecon drive angle gear, and

set on the mechanism chassis as shown below.

Casecon

Casecon drive angle gear

-7

Weight to prevent

Figure 4-3.

Note:

The weight should not be more than 500g.

0 To take out the cassette tape.

1. Turn off the power switch.

2. Take out the cassette tape.

Mechanism chassis

Figure 4-2.

2. Install in the reverse order of removal.

XA-705 XA-71 O,XA-720

(BOTTOM VIEW)

. Function

15 Drum ass’y 22 Reel belt

16 Loading motor 23 Clutch lever

17 Drum motor 24 Limiter pulley ass’y

18 Tu pole base ass’y 26 Shifter

19 Slow brake 27 Fixing guide

20 Master cam

21 Capstan D.D. motor

XA-705 XA-71 O,XA-720

MECHANISM ADJUSTMENT, REPLACEMENT, ASSEM-

4. BLING AND CLEANING METHODS

The explanation given below relates to the on-site general service (field service) but it does not relates to the adjustment and replacement which need high-grade equipment, jigs and skill. For example, the drum assembling, replacement and adjustment service must be performed by the person who have finished the technical courses.

4-l MECHANISM CONFIRMATION ADJUSTMENT JIG

So as to perform completely the mechanism adjustment prepare the following special jigs. So as to maintain the initial performance of the machine the maintenance and check are necessary. Utmost care must be taken so that the tape is not damaged. If adjustment needs any jig, be sure to sue the required jig.

Torque Cassette Meter

Jig Item

Part No.

JiGVHT-063 CZ

Code Configuration

&!5$2@

Remarks

This cassette torque meter is used for checking and adjusting the torque of take-up for measuring tape back tension.

These Jigs are used for checking and adjusting the torque of take-up and supply reel disks.

and adjusting the reel disk height.

transformer clearance

10 Guide roller height

’ adjustment drive

X value adjustment

“*

gear type screw driver

Reverse Guide Height

Adjusting Jig

JiGDRiVERH-4 AP

JiGDRiVER- BM @------$$

JiGRVGH-F18 BU

This screwdriver is used for adjusting the

guide roller height.

For X value adjustment

This Jig is used for height

adjustment of the reverse guide.

XA-705 XA-71 O,XA-720

MAINTENANCE CHECK ITEMS AND EXECUTION TIME

Perform the maintenance with the regular intervals as follows so as to maintain the quality of machine.

500 1000 1500 2000 hrs. hrs. hrs. hrs.

Guide Roller Ass’y

Sup Guide Shaft

Retaining Guide cl

cl 0 q

Cl cl

Slant Pole or Pole Base cl (7 q

Reverse Guide Shaft Tension Pole

Full-erase Head

A/C Head

Upper and Lower Drum Ass’y

Capstan D.D Motor

Pinch Roller Ass’y 0

I7 0 q

ocl on 00

II 0 0 q

Possible symptom

encountered

Lateral noises Head occasionally blocked

CII

Poor color and beating

Small sound or distortion sound Poor S/N ratio, no color

Poor flatness of the envelope with alignment tape

No tape running, uneven color

No tape running, tape slack

No tape running, tape slack, no fast forward/rewind

Reel Belt

Tension Band Ass’y

Loading Motor

Idler Ass’y

motion

0 Screen Swaying 0

Cassette not loaded or unloaded

No tape running, tape slack

Limiter Pulley Ass’y 0

SUP/TU Main Brake Levers 0

Tape Slack

Reel Disk /\

AHC (Auto Head Cleaner)

NOTE:

0: Part replacement, Cl : Cleaning, n : Apply grease

Replace when roller dirted

Loading Motor, Guide Roller Ass’y and FE Head are replaced at about 2000 hrs.

<Specified> Cleaning liquid: Industrial ethyl alcohol

* This mechanism does not need electric adjustment with variable resistor. Check parts. If any deviation is

found, clean or replace parts.

3. FUNCTION OF MAJOR MECHANICAL PARTS

(TOP VIEW)

n 37

XA-705 XA-71 O,XA-720 !O

Full erase head Sup pole base ass’y Tension arm Idler ass’y Pinch drive lever ass’y Supply reel disk Sup main brake 14

Function No .

Tu main brake

Pinch drive cam

NC Head ass’y

Reverse guide

Casecon drive gear

Take-up reel disk

Pinch roller lever ass’y

Function

XA-705

r XA-71 O,XA-720

REEL DISK REPLACEMENT AND HEIGHT

CHECK

Removal

Remove the cassette housing control assembly.

1. .

Pull the tension band out of the tension arm ass’y.

Remove the Sup/Tu main brake ass’y.

3 4:

Open the hook at the top of the reel disk, and remove

the reel disk.

Note:

Take care so that the tension band ass’y and main brake

ass’y (especially soft brake) are not deformed.

Tension arm ass’y

Sup main brake ass’y

Tension band ass’y

Supply reel’ disk

Tu main brake ass’y

Take-hp reel disk

Notes:

1 .

When installing the reel disk, take due care so that the tension band ass’y is not deformed and grease does

no adhere.

Do not damage the Sup main brake ass’y. Be careful

so that grease does not adhere to the brake surface.

Reassembly (Take-up reel disk)

Clean the reel disk shaft and apply grease (SC-141) to it.

. d

Align the phase of the reel disk to that of the reel relay gear and to install a new take-up reel disk onto the

shaft.

Check the reel disk height and reassemble the takeup main brake ass’y.

Notes:

I. Take care so that the Tu main brake ass’y is not

damaged. Take care so that grease does not adhere the brake surface.

2. After reassembly, check the video search rewind back tension (see page 17) and check the brake

torque (see page 19).

l Height checking and adjustment

Notes:

Set the master plane with due care so that it does not contact the drum.

2 .

When putting the master plane, shift the reverse guide a little in the loading direction. Care must be taken since excessive shift results in damage.

Figure 4-4.

Note:

When the tension band a&y is pressed in the direction of the arrow for removal, the catch is hard to be deformed.

Figure 4-5.

Reassembly (Supply reel disk)

Clean the reel disk shaft and apply grease (SC-141) to it.

1 .

Match the phases of reel disk and reel relay gear, and

2 .

set the new reel disk. After checking the reel disk height, wind the tension

3 .

band ass’y around the reel disk, and insert into the

hole of tension arm ass’y.

Assemble the Sup main brake ass’y.

4 .

Myter plane

SUPPl

Take-up reel disk

Figure 4-6.

Note:

Check that the reel disk is lower than part A but higher

than part B. If the height is not correct, readjust the reel

disk height by changing the poly-slider washer under the reel disk.

Note:

Whenever replacing the reel disk, perform the height

checking and adjustment.

Reel disk height adjusting jig

10+0.2mm + ,

Reel disk

I f

Mechanism chassis

fjqgy

Reel disk

Figure 4-7.

CHECKING AND ADJUSTMENT OF TAKE-UP TORQUE IN FAST FORWARD MODE

Remove the cassette housing control assembly.

After short-circuiting TP801 provided at the center (facing to the main PWB), plug in the power cord.

Setting

Set a torque gauge to zero on the scale. Place it on

1. the take-up reel disk.

Press the FF button.

To calculate the remaining capacity of the play back

mode, slowly rotate the supply reel disk, and then

shift it into the forward mode.

Checking

Turn the torque gauge slowly (one rotation every 2 to

3 seconds) by hand in the CW direction.

Make sure that the indication of torque gauge is not

less than 30mN.m (306gfcm).

Notes:

1. Hold the torque gauge by hand so that it is not moved.

2. Do not keep the reel disk in lock state. Do not allow long-time measurement.

CHECKING AND ADJUSTMENT OF TAKE-UP

TORQUE IN REWIND MODE

Remove the cassette housing control assembly.

After short-circuiting TP801 provided at the center (facing to the main PWB), plug in the power cord.

Setting

Set a torque gauge to zero on the scale. Place it on the supply reel disk.

Press the rewind button.

To calculate the remaining capacity, slowly rotate the

take-up reel disk, and then shift it into the rewind

mode.

Checking

Turn the torque gauge slowly (one rotation every 2 to

3 seconds) by hand in the CCW direction.

Make sure that the indication of torque gauge is not less than 30mN*m (306gfcm).

Torque gauge

30mN.m (306gf-cm) or more

Torque gauge

30mN-m (306gf.cm) or more

Idler ass’y

The gauge is held at

its maximum value. (Red mark)

Figure 4-8.

Adjustment

. . If the FF winding-up torque is less than the specified

value, clean the capstan D.D. motor pulley, drive belt, and limiter pulley with cleaning liquid, and check again.

2. If the torque is less that the set value, replace the reel belt.

-_ The gauge is held at its maximum value. (Red mark)

disk

r ass’y

Figure 4-9.

Adjustment

I . If the rewind winding-up torque is less than the

specified value, clean the capstan D.D. motor pulley, drive belt, and limiter pulley with cleaning liquid,

rewind again, and check the winding-up torque.

2. If the winding-up torque is still out of range, replace the drive belt.

Notes:

1. Hold the torque gauge by hand so that it is not moved.

2. Do not keep the reel disk in lock state. Do not allow long-time measurement.

XA-705 XA-71 O,XA-720

CHECKING AND ADJUSTMENT OF TAKEUPTORQUE IN RECORD/PLAYBACKMODE

Remove the cassette housing control assembly.

After short-circuiting TP801 provided at the center

(facing to the main PWB), plug in the power cord.

Turn off the power switch.

Open the cassette torque meter lid, and fix it with tape.

Load the cassette torque meter into the unit. Put the weight (500g) on the cassette torque meter.

Turn on the power switch.

Press the picture record button, and set EP pic-

ture record mode (x3).

Set value EP6.9 + 2.5mN.m (70 + 25gf-cm)

CHECKING AND ADJUSTMENT OF TAKEUP TORQUE IN VIDEO SEARCH REWIND MODE

l -Remove the cassette housing control assembly.

l After short-circuiting TP801 provided at the center

(facing to the main PWB), plug in the power cord.

l Setting

Press the playback button and rewind bu the video search rewinding mode.

l Checking

1. Place the torque gauge on the supply ree turn it counterclockwise very slowly (one rotation

every 1 to 2 seconds) and check that the torque is

within the set value 14.0 k 3.9mN.m. (144 k 40gfcm)

Torque gauge

ton to set

disk, and

ccw

Figure 4-l 0.

Checking

1 .

Make sure that value is within the setting 6.9+2.5mN.m

(70*25gfcm).

2 .

The winding-up torque fluctuates due to variation of

rotation torque of limiter pulley ass’y. Read the center

value of fluctuation as setting.

Set the EP record mode (x3) and make sure that the

winding-up torque is within setting.

Adjustment

the playback winding-up torque is not within the

setting, replace the limiter pulley assembly.

Note:

When the torque cassette is set, put a weight (500g) to

prevent rise. When the cassette torque meter is taken out. Turn off the power switch.

Supply reel disk

Figure 4-11.

Note:

Surely put the torque gauge on the reel disk to measure.

If the torque gauge is raised, accurate measurement is impossible.

l Adjustment

1. If the rewinding playback winding-up torque is not

within the setting, replace the limiter pulley assembly.

Note:

The winding-up torque fluctuates due to variation of

rotation torque of supply reel disk. Read the center value of fluctuation as setting.

CHECKING THE VIDEO SEARCH REWIND

BACK TENSION

Remove the cassette housing control assembly.

XA-705

XA-71 O,XA-720

After short-circuiting TP801 provided at the center (facing to the main PWB), plug in the power cord.

Checking

After pressing the play button, press the rewind button, and set the video search rewind mode.

Place the torque gauge on the take-up reel disk, and turn it counterclockwise very slowly (one rotation every 2 to 3 seconds) and check that the torque is within the set value 3.4+1.5mN.m (35+15gfcm).

Torque gauge

ccw

Take-up reel disk

Figure 4-l 2.

Note:

Set the torque gauge securely on the take-up reel disk. If it is not secure, the measurement will be incorrect.

CHECKINGTHE PINCH ROLLER PRESSURE

l Remove the cassette housing control assembly.

l After short-circuiting TP801 provided at the center

(facing to the main PWB), plug in the power cord.

Tension gauge 900 - 1,200g

Capstan shaft

Detach the pinch roller from the capstan shaft. Do not separate excessively. Or the pinch lever and pinch double action lever may disengage.

Engage the tension gauge adapter with the pinch roller shaft, and pull in the arrow direction.

Gradually return the pinch roller, and measure the

pulling force when the pinch roller contacts the capstan shaft.

Make sure that the measured value is within setting

0.9 to 11.8 N (900 to 1,200g).

Tension gauge adapter

Figure 4-13.

CHECKING AND ADJUSTMENT OF

TENSION POLE POSITION

l Remove the cassette housing control assembly.

l After short-circuiting TP801 provided at the center

(facing to the main PWB), plug in the power cord.

l Setting

1. Turn off the power switch.

2. Open the cassette tape (T-120), and fix with tape.

3. Set the cassette tape in loading state.

4. Put the weight (500s) on the cassette tape.

5. Turn on the power switch.

6. Make the adjustment with the beginning of a T-120 tape.

0 Checking

Press the play button to set the playback mode.

Weight to prevent float (500s)

Figure 4-l 4.

XA-705

XA-71 O,XA-720

Checking

Set a cassette unit in the SP

tape, push the REC button to place the

record mode. Now check the tension

pole position.

Visually check to see if the right edge of the tension

pole is within the 1.5 + 0.25mm from the right edge of

the Sup guide shaft.

Sup guide shaft

A-h

Make the adjustment with the beginning of a T-120 tape.

Figure 4-15.

At left side from the center line

Tension pole adjuster adjusting range

Tension pole

Figure 4-18.

Adjust so that the delta mark of tension pole adjuster

is within 90” range (left, right).

CHECKING AND ADJUSTMENT OF RECORD/PLAYBACK BACK TENSION

Remove the cassette housing control assembly.

1.5 * 0.25mm

Figure 4-l 6.

Insert the slotted screwdriver in the tension pole ad-

juster, and rotate counterclockwise.

At right side from the center line

After short-circuiting TP801 provided at the center (facing to the main PWB), plug in the power cord.

Setting

Turn off the power switch.

Open the torque cassette meter and fix with tape.

Set the cassette tape in loading state.

Put the weight (500g) on the cassette torque meter.

Turn on the power switch.

Weight to prevent float (500g)

Cassette torque meter

Figure 4-19.

1.5 k 0.25mm

Figure 4-l 7.

Insert the slotted screwdriver in the tension pole ad-

juster, and rotate clockwise.

Checking

Push the REC button to place the unit in the SP record mode.

At this time ascertain that the back tension is within the setting (36.5 to 52gcm) by seeing the indication of torque cassette meter.

l Adjustment

1. If the indication of torque cassette meter is lower than

the setting, shift the tension spring engagement to the part A.

2. If the indication of torque cassette meter is higher than the setting, shift the tension spring engagement to the part 9.

A B +---+

Tension arm

Tension spring

XA-705 XA-71 O,XA-720

Checking the brake torque at the take-up side

Torque

Take-1

up reel K ‘//

disk

Figure 4-20.

CHECKING THE BRAKE TORQUE

Checking the brake torque at the supply side

Torque gauge

Supply reel disk

3.9-9.8mN.m (40-I OOgfxm)

8.8-23.5mN.m (80-245gf.cm)

Figure 4-21.

Remove the cassette housing control assembly.

CCW: 8.8-23.5mN.m (80-245gf.cm) cw: 4.9-11.8mN.m (50-I 20gf.cm)

Figure 4-22.

Remove the cassette housing control assembly.

After short-circuiting TP801 provided at the center (facing to the main PWB), plug in the power cord.

Setting

Switch from the FF mode to the STOP mode.

2 .

Disconnect the power cord. .

3 .

Set a torque gauge to zero on the scale. Place it on

the take-up reel disk.

Checking

Turn the torque gauge at a rate of about one turn/2 set in the CCW direction/CW direction so that the reel disk and torque gauge pointer rotates at equal speed and make sure that the value is within the setting (CCW direction: 8.8 to 23.5mN.m (80 to 245gfcm), CW direction: 4.9 to 11.8 mN-m (50 to 120gfcm).

After short-circuiting TPSOI provided at the center (facing to the main PWB), plug in the power cord.

Setting

Set a torque gauge to zero on the scale. Place it on

1 .

the supply reel disk. Switch from the FF mode to the STOP mode.

2 .

Disconnect the power cord.

3 .

Checking

Turn the torque gauge at a rate of about one turn/2 set in the CW direction/CCW direction with respect to the supply reel disk so that the reel disk and torque gauge pointer rotate at equal speed, and make sure that the value is within the setting (CW direction: 8.8 to 23.5mN.m (80 to 245gfcm); CCW direction: 3.9 to

9.8mN*m (40 to 1OOgfcm).

Adjustment of the brake torque at the supply side and

the take-up side

Unless the supply side brake torque or take-up side brake torque is within the setting, clean the felt surface of reel disk (supply, take-up) brake lever, check again the brake torque.

If value cannot be set within the setting yet, replace the main brake ass’y or main brake spring.

XA-705 XA-71 O,XA-720

REPLACEMENT OF A/C (Audio/Control) HEAD

1. Remove the cassette housing control assembly.

2. In unloading state unplug the power cord.

l Removal

1. Remove the screws @@@, Azimuth screw and Tilt screw.

2. Unsolder the PWB fitted to the A/C head

Notes:

When replacing, never touch the head. If you touched,

1. clean with the cleaning liquid.

2. When removing the screw 0, take care so that the spring may spring out.

3. Align the left end of gear of A/C head arm with the

punched mark of chassis, tentatively tighten the screws @ and @ so as to ensure smooth motion of A/C head arm. Tentative tightening torque must be

0.15 to 0.20 N*m (1.5 to 2.0kgfcm).

Figure 4-25.

Notes:

1 .

If the screws @ and @ loose, the azimuth and change when they are finally tightened. Therefore care must be taken.

After completion of A/C head be sure to adjust tape drive train. (Execute the running adjustment by the method described in Page 22, 23.)

are tighten tentatively too height of A/C head may

Figure 4-23.

Replacement

Solder the removed PWB to the new head assembly.

2. Adjust the height from the A/C head arm (lower

surface) to the A/C head plate to 10.8mm with slide calipers. (3 places of azimuth screw section, tilt screw section and A/C head front section)(See the figure below.)

Solder

head PWB

Never touch the head

A/C head plate

10.8mm

Figure 4-24.

XA-705

i XA-71 O,XA-720

A/C HEAD HEIGHT ROUGH ADJUSTMENT

l Setting

f@ \

Cassette tape

Mechanism chassis

Weight to prevent float (500g)

Height screw

Azimuth screw

Tilt &rew

Figure 4-26.

HEIGHTADJUSTMENTOFREVERSEGUIDE

1 Adjust the height from the mechanism chassis to the

reverse guide lower flange to 13.38 mm, using the reverse guide height adjustment jig, in tape loading state. (Refer to Figure 4-28 (a) (b).)

Reverse guide height adjusting jig

Reverse guide height J

adjusting jig

Reverse guide

Mechanism

chassis

Figure 4-28.

Rotate counterclockwise the reverse guide height adjustment nut l/l 0 turn. (For height adjustment use the reverse guide height adjustment box driver

(JiGDRiVER 1055)).

Box driver

ccw

13.38mm

1. Set the cassette tape in the unit.

2. Press the PLAY button to put the unit in the playback

mode.

3. Roughly adjust the height of the A/C head by turning the height screw until the tape is in the position shown

below.

A/C head 3

Figure 4-27.

0 Adjustment

Adjust the height screw visually so that the control head is visible 0.3mm below the bottom of the tape.

Height adjusting nut

Figure 4-29.

u. Set the tape, and check for tape crease near the

reverse guide in the playback mode. If crease is found, turn the reverse guide adjustment nut to remove crease. (As for crease check refer to Figure 4-30.)

Capstan

/‘motor shaft

Jide

Reverse guid;

L- En example of

crease near the reverse guide

Fixing gi

* Check for crease

from the A direction.

Figure 4-30.

XA-705

XA-71 O,XA-720

ADJUSTMENT

1. Tape run rough Remove the

OF TAPE DRIVE TRAIN

adjustment

cassette housing control assembly. After shortcircuiting TP801 provided at the center (facing to the main PWB), plug in the power cord. Check and adjust the position of the tension pole. (See page 17.) Check and adjust the video search rewind back tension. (See page 17.) Connect the oscilloscope to the test point for PB CHROMA envelope output (TP201). Set the synchronism of the oscilloscope to EXT. The PB

CHROMA signal is to be triggered by the head

switching pulse (TP202). Set the alignment tape (VROATSV) to play. (Put a 500g weight on the cassette tape to prevent lift of cassette tape.)

Guide roller

Figure 4-32.

2. Adjustment of A/C head height and azimuth @ Perform the initial setting of A/C head position by

the method stated in “Page 20 Replacement -3.“.

@ Connect the oscilloscope to the audio output

terminal.

@ Using the alignment tape in which 1 kHz linear

audio signal has been recorded, adjust the height screw so as to get max audio output.

@ Using the alignment tape in which 7 kHz linear

audio signal has been recorded, adjust the azimuth screw so as to get max audio output.

@Repeat the above steps @ and @ a couple of

times. Finally make the above adjustment step

@ Bp

c-7

Figure 4-31.

Press the tracking button (+), (-) and change the envelope waveform from max to min and from min to max. At this time make sure that the envelope waveform changes nearly parallel. Unless the envelope waveform changes nearly parallel, adjust the height of supply side and takeup side guide roller so that the envelope waveform changes nearly parallel. (For envelop ad-

justment procedure refer to Figure 4-35.)

Turn the tilt screw to remove the tape crease at

the fixing guide flange. ,

Play back the tape and check for tape crease at

the fixing guide flange.

(1) If there is no tape crease

Turn the tilt screw clockwise so that tape crease appears once at the flange, and then

return the tilt screw so that the crease disappears.

(2) If there is tape crease

Turn counterclockwise the tilt screw so that the tape crease disappears.

(Reference) If the tilt screw is turned clockwise

crease appears at the lower flange.

Previously set the tracking control in the center position, and adjust the envelop waveform to maximum with X value adjustment nut. Thereby the tape run

rough adjustment is facilitated.

Especially the outlet side envelope waveform must

have higher flatness.

I- For X value adjustment

Adjust the X value, turning the geartype screwdriver.

Figure 4-33.

3. Tape run adjustment Connect the oscilloscope to PB CHROMA envelope output test point, set oscilloscope sync to EXT, trigger-input the PB CHROMA signal (head switching pulse). Rough adjustment of X value Tentatively fixA/C head arm screws @ and @ by the method described in Page 20 “Replacement

-3 Play back the alignment tape (VROATSV), and

shortcircuit TP802. As a result the auto-tracking is automatically cancelled, so that the X value adjustment mode is set.

Move the A/C head with the X value adjustment

gear driver (JiGDRiVER-6) by the method shown

in Figure 4-33, and adjust the A/C head so as to

get the maximum envelope waveform. (Note: When the A/C head is adjusted, adjust so that the maximum envelop waveform is obtained nearest the position of initial setting made in Page 20.)

@ Next, change the alignment tape to VROEFZCS

to playback. Press the tracking button (+), (-) and change the envelope waveform from max to min and from min to max. At this time adjust the height of supply and take-up side guide roller with the

adjustment driver (JiGDRiVERH-4) so that the envelope waveform changes nearly parallel.

If the tape is lifted or sunk from the helical lead surface, the PB CHROMA envelope waveform appears as shown in Figure 4-35. Press the tracking button (+), (-) and make sure that the envelope waveform changes nearly parallel. Finally check tape crease near the reverse guide. If tape crease is found, remove it as stated in Page 21 “HEIGHT ADJUSTMENT OF REVERSE GUIDE” item 3.

XA-705 XA-71 O,XA-720

PB CHROMA _ Envelope

Head switching pulse

Figure 4-34.

When the tape is above the helical lead.

I-

Supply side

Supply side guide roller rotated in clockwise direction (lowers guide roller) to flatten

Adjustment

envelope.

4. A/C head X value adjustment

Tentatively fix A/C head arm screws @ and @ by the method described in Page 20 “Replacement

-3 Playback the alignment tape (VROEFZCS), and

shortcircuit TP802. As a result the auto-tracking is automatically cancelled, so that the X value adjustment mode is set.

Move the A/C head with the X value adjustment gear driver by the method shown in Figure 4-33,

and adjust the A/C head so as to get the maximum

envelope waveform. (Note: At this time adjust so as to get the maximum envelope waveform nearest the A/C head position which has been set in case of X value rough adjustment as stated in Page 22,3-a). Tighten finally the screws @ and 0. Be sure to tighten at firstthe screw @ and then the screw 0. Final tightening torque is 0.6N.m (If the screw @ is tightened first, the X value may deviate.)

Take-up side

i:i”

Take-up side guide roller rotated in clockwise direction (lowers guide roller) to flatten envelope.

Figure 4-35.

Note:

When the A/C head X value adjustment is performed, be sure to perform at first X value rough adjustment (refer to Page 22,3-Q).

When the tape is below the helicallead.

Supply side

Take-up side

. /

Supply side guide roller Take-up side guide roller rotated in counterclock- rotated in counterclock-

wise direction (raises wise direction (raises

guide roller) to make the guide roller) to make the

tape float above the helical tape float above the

lead. The supply helical lead. The take-up side guide roller is then rotated in the clockwise rotated in the clockwise direction to flatten the direction to flatten the envelope. envelope.

side guide roller is then

-_H

Adjust the playback switching point (Refer to the electric adjustment method.) Playback the self-picture-recorded tape, and check the flatness of envelope waveform and sound.

Figure 4-36.

XA-705 XA-71 O,XA-720

REPLACEMENT OF THE CAPSTAN D.D.

(DIRECT DRIVE) MOTOR

l Remove the mechanism from the main PWB. (Refer

to Page 7 “When removing the mechanism from

the main PWB.“)

l Removal (Follow the order of indicated num-

bers.)

1. Remove the reel belt 0.

2. Remove the three screws @.

motor

Capstan D.D. motor

REPLACEMENT OF DRUM D.D. MOTOR

1 .

Set the ejection mode.

2 .

Withdraw the main power plug from the socket.

Removal (Perform in numerical order.)

1 .

Disconnect the FFC cable 0.

2 .

Unscrew the D.D. stator assembly fixing screws 0.

Take out the D.D. stator assembly 0.

Unscrew the D.D. rotor assembly fixing screws @.

Take out the D.D. rotor assembly 0.

Notes:

In removing the D.D. stator assembly, part of the drum earth spring pops out of the pre-load collar. Be careful not to lose it.

Install, so that the D.D. rotor ass’y and upper drum ass’y mounting direction check holes align. (Align the upper drum dent with the rotor hole.)

Be careful not to damage the upper drum or the video head.

Protect the hole elements from shock due to contact with D.D. stator or D.D. rotor ass’y.

After installation adjust the playback switching point for adjustment of servo circuit.

Reel belt

Figure 4-37.

Reassembly

Taking care so that the capstan shaft does not

contact the mechanism chassis, set its position on the mechanism chassis, and then install with the three screws.

2. Install the reel belt. Notes:

1. After installing the capstan D.D. motor, be sure to rotate the capstan D.D. motor and check the movement.

2. Set the tape, and check for the tape crease near the reverse guide in the playback mode. Adjust the A/C head and azimuth as stated in Page 22 item 2. If crease is found, adjust as stated in Page 21 “HEIGHT ADJUSTMENT OF REVERSE GUIDE”.

D.D. stator ass’y

FFC

1. rotor ass’y

Upper drum

Figure 4-38.

XA-705

XA-71 O,XA-720

REPLACING THE UPPER AND LOWER DRUM ASSEMBLY

l Replacement (Perform in the numerical order)

@ Remove the motor as stated in Page 24 D.D. motor

replacement.

@ Remove the drum earth brush 8.

Remove the dru

drum assembly 0 .

[Cares when replacing the drum]

Be careful so that the drum earth brush is not lost.

2 .

Do not touch directly the drum surface.

Fit gently the screwdriver to the screws.

Since the drum assembly is an extremely precise assembly, it must be handled with utmost care.

Make sure that the drum surface is free from dust, dirt

and foreign substances.

After replacing the drum be sure to perform the tape

running adjustment. After that, perform also the electrical adjustment.

l Playback switching point adjustment l X-position adjustment and check l Standard and x-3 slow tracking adjustment

After replacing the drum clean the drum.

m base

@ from the

upper

and lower

ASSEMBLING OF PHASE MATCHING MECHANISM COMPONENTS

Assemble the phase matching mechanism components in the following order.

1 .

Assemble the pinch roller assembly and pinch drive cam.

Mounting the shifter (on the back of the mechanism

chassis).

3 .

Mounting the master cam (on the back of the mechanism chassis).

Assemble the connection gear, slow brake and load-

ing motor parts.

Pinch drive cam and pinch roller assembling

method. (Place the following parts in position in numerical order.)

(l)Reverse drive lever @ (2)Reverse guide spring @ (3)Reverse guide lever ass’y @ (4)Reverse guide height adjusting nut @ (5)Pinch drive cam @ (6)Pinch roller ass’y @ (7)Open lever 0

Figure 4-39.

Figure 4-40.

XA-705 XA-71 O,XA-720

@Insert Reverse Guide Lever Ass’y

@ Insert pinch drive cam

Insert reverse guide lever

Fit the pinch drive cam so that the notch of pinch drive cam aligns with the dent of pinch drive lever

- Fit the pinch drive cam so that the notch of

pinch drive lever assembly aligns with the

half-round notch of chassis.

ass’y

Pinch drive lever ass’y

Figure 4-41-l.

@Insert Pinch Roller/Pinch Double Action Lever Ass’y.

Pinch Roller Double Action Lever Ass’y

Phase Matching Point @

@Insert Open Lever.

Open lever

Figure 4-41-2.

Figure 4-41-3.

INSTALLING THE SHIFTER

Capstan D.D. moto

Reel pulley

Drum

/ iK&w*o

Make sure that the loading gear is at the point @ as shown below.

Install, paying attention to @ insertion points and @

release points.

For the phase matching at the insertion point 0, see the point @ as shown below.

Finally fix the inserts @ and @.

(Bottom side of mechanism chassis)

Figure 4-42.

Insert point @

Phase-Matching point @

notch

-/Y I

/ \ / -I

Rotatior)(\l /

Figure 4-43.

Insert

- point @

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