SHARP XA-905, XA-920 Service Manual

SERVICE MANUAL

XA-905

SERVICE MANUAL

S80E5XA-905//

PROFESSIONAL SERIES VIDEO CASSETTE RECORDER

XA-905

XA-920

ROFESSIONAL SERIES VIDEO CASETTE RECORDER

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

2. DISASSEMBLY AND REASSEMBLY............................................................................................ 6

3. FUNCTION OF MAJOR MECHANICAL PARTS ...........................................................................9

4. ADJUSTMENT, REPLACEMENT AND ASSEMBLY OF MECHANICAL UNITS ........................ 11

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

6. MECHANISM OPERATION FLOWCHART AND TROUBLESHOOTING GUIDE ...................... 32

7. TROUBLESHOOTING................................................................................................................. 38

MODELS XA-905/XA-920

8. BLOCK DIAGRAM.......................................................................................................................50

9. SCHEMATIC DIAGRAM AND PWB FOIL PATTERN..................................................................58

10. PARTS LIST ................................................................................................................................73

11. EXPLODED VIEW OF MECHANICAL PARTS............................................................................81

12. PACKING OF THE SET .............................................................................................................. 86

XA-920

MODELS

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.

CONTENTS

XA-920

Page

SHARP CORPORATION

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

XA-905 XA-920

IMPORTANT SERVICE NOTES

BEFORE RETURNING THE VIDEO CASSETTE RECORDER

Before returning the video 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 etc.

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

● Plug the AC line cord directly into a 120 volt AC outlet (Do not use an isolation transformer for this test).

● Using two clip leads, connect a 1.5k ohm, 10 watt resistor paralleled by a 0.15µF capacitor in series with all exposed metal cabinet parts and a known earth ground, such as a water pipe or conduit.

● Use an SSVM or VOM with 1000 ohm per volt, or higher, sensitivity or measure the AC voltage drop across the resistor (See Diagram).

● Move the resistor connection to earth exposed metal part having a return path to the chassis (antenna, metal cabinet, screw heads, knobs and control shafts,

etc.) and measure the AC voltage drop across the resistor. Reverse the AC plug on the set and repeat AC voltage measurements for each exposed part. Any reading 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.

SSVM

AC SCALE

1.5k ohms. 10W

0.15 µF

TEST PROBE

TO EXPOSED METAL PARTS

CONNECT TO KNOWN EARTH GROUND

WARNING :TO REDUCE THE RISK OF FIRE OR ELEC-

TRIC SHOCK, DO NOT EXPOSE THIS APPLIANCE TO RAIN OR MOISTURE.

CA UTION

RISK OF ELECTRIC SHOCK

DO NOT OPEN

CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK. DO

CAUTION:

3.0A 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 (3.0A, 125V).

XA-905 XA-920

PRECAUTIONS IN PART REPLACEMENT

When servicing the unit with power on, be careful to the section marked white all over. This is the primary power circuit which is live.

When checking the soldering side in the tape travel mode, make sure first that the tape has been loaded and then turn over the PWB with due care to the primary power circuit. Make readjustment, if needed after replacement of part, with the mechanism and its PWB in position in the main frame.

(1) Start and end sensors: Q701 and Q702

Insert the sensor’s projection deep into the upper hole of the holder. Referring to the PWB, fix the sensors tight enough.

(2) Photocoupler: IC901

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

(3) Cam switches A and B: D708 and D709.

Adjust the notch of the part to the white marker of the symbol on the PWB. Do not allow any looseness.

(4) Take-up and supply sensors: D707 and D706.

Be careful not to confuse the setting direction of the parts in reference to the symbols on the PWB. Do not allow any looseness.

XA-905 XA-920

1. GENERAL INFORMATION

1-1. FEATURES

Only for XA-905

• Universal Remote Control

Only for XA-920

• Hi-Fi Stereo Sound

• Built-in MTS (Multi-channel TV Sound) Decoder

• * The VCR Plus+ Programming System

• Automatic Head Cleaning System

• Built in Front AV Jacks

• Universal Remote Control with light up buttons Common Features

• 400 Times Rewind Speed to Fast Forward and Rewind.

• EZ Set Up

• S-VHS Quasi Playback

• Double-Azimuth 4-Heads

µ Clear Picture System (in EP mode)

•19

• HQ System for Better Resolution and Color Reproduction

• Multi-Language (English/Spanish/French) OSD (On Screen Display) with Menu Screen Guidance

• 181-channel PLL Quartz Synthesized Random Access Tuner with Automatic Channel Setting

• Quick Start with Full Loading Mechanism

• 1-Year, 8-Event Programmable Timer

• Simple Recording Timer

• Sharp Super Picture

• Rec Tab Override

• Remote Pause IN/OUT Jacks

• BNC Video Connectors

• 3-Wire (Grounded) AC Power Cord

• 1 hour Timer Backup

• Field-Still/Variable Slow/Frame Advance

• Real-Time Counter

• Automatic Daylight Saving-Time (D.S.T.) Adjustment

• Blue Screen Noise Elimination

• Auto Tracking Control System

• Digital Program Search System (DPSS)

• Skip Search

• Instant Replay

• Exact Rec

• Tape Remaining

• One-Step Rewind

• Auto Zero Back

• Recorded Section Auto Repeat

• Full Automatic Playback

• Tamper Proof

• Up to 8 Hours of Recording and Playback (with T-160 cassette)

1-2. SPECIFICATIONS

Format: VHS NTSC Standard

Video Recording System: Rotary, Two-Head Helical Scanning

Number of Video Heads: 4

Video Signal Standard: NTSC Color System

Audio Recording System: 1 Stationary Head for Linear Audio

Tape Width: 12.7 mm (1/2 inch)

Tape Speed: (SP) 33.35 mm/sec (1.31 i.p.s.)

Maximum Recording Time: (SP) 160 min (T-160)

Channel Coverage: VHF 2-13

Antenna Input: 75 Ohm

Video Input: 0.5 to 2.0 Vp-p, 75 Ohm unbalanced

Video Output: 1.0 Vp-p, 75 Ohm unbalanced

Audio Input: –8 dBs, 47 kOhm unbalanced (0 dBs = 0.775 Vrms)

Audio Output: –8 dBs, 1 kOhm unbalanced (0 dBs = 0.775 Vrms)

Hi-Fi Audio (Only for Hi-Fi model):

Memory Backup: 1 hour

Operating Temperature: 5°C to 40°C (41°F to 104°F)

Storage Temperature: –20°C to 60°C (–4°F to 140°F)

Power Source: 120 V AC, 60 Hz

Power Consumption: 18 W

Dimensions (approx.): 360 (W) x 92.5 (H) x 262.5 (D) mm (14-3/16" x 3-41/64" x 10-21/64") (XA-905)

Weight (approx.): 2.8 kg (6.2 lbs)

Accessories included: 75 ohm coaxial cable, Operation manual, Infrared remote control, Battery (2 pcs.),

Note: Specifications are subject to change without notice.

2 Rotary Heads for Hi-Fi stereo (Only Hi-Fi model)

(LP) 16.67 mm/sec (0.66 i.p.s.) (playback only) (EP) 11.12 mm/sec (0.44 i.p.s.)

(EP) 480 min (T-160) UHF 14-69

CATV 1-125

Dynamic Range: Frequency Response:

90 dB

20 Hz-20 kHz

360 (W) x 92.5 (H) x 263.5 (D) mm (14-3/16" x 3-41/64" x 10-3/8") (XA-920)

Warranty Card

POWER button

(When pressed to turn on the VCR, some indicators

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

Function display brightens. When the power is turned off,

the Multi-Function display dims.)

Major Components of Your VCR

[Front]

Multi-Function Display (explained throughout the operation instructions)

TIMER

REC

VCR SPEP

Display

Symbol Function Status

Stop

Play

Fast forward

Rewind

Cassette-in

Video Search, Slow,

Still, Frame Advance

Tamper Proof

Active

Unit in

VCR mode

Record

VCR

Display

Symbol Function Status

REC

Rec Pause

[Rear]

! Channel setting @ Tape counter # Clock

Cassette compartment (see Playback/Recording)

Basic function controls

(see Playback/Recording)

When the power is on, each time DISPLAY is pressed,

the Multi-Function display changes as follows:

•Tape counter is displayed during playback, fast forward or rewind operation.

•When the power is turned off, the clock is displayed and the Multi-Function display becomes darker.

•The display will return to the original mode (counter or clock display) 3 seconds after the

VCR enters the operation mode.

Connection terminals (see Connecting the VCR and

Cable TV Connections)

Connection terminals (see Tape Dubbing)

3 ↔ 4 OUTPUT CHANNEL selector

(see Setting the 3 ↔ 4 Output Channel Selector)

(XA-920)

Connection terminals (see Connecting the VCR and

Cable TV Connections)

Connection terminals (see Tape Dubbing)

3 ↔ 4 OUTPUT CHANNEL selector

(see Setting the 3 ↔ 4 Output Channel Selector)

(XA-905)

1-3. LOCATION OF MAJOR COMPONENTS AND CONTROL

VIDEO CASSETTE RECORDER

Remote Control

MENU button

Remote Control Mode Select

buttons (VCR, TV, CABLE/SAT.)

• USED TO SELECT THE

COMPONENT (VCR, TV, CABLE

BOX/SAT.) TO BE OPERATED.

DISPLAY button

ON SCREEN button

SET button

VCR Plus+ button

ZERO BACK button

SKIP SEARCH button

REPLAY button

PAUSE/STILL button

TAMPER PROOF button

*STOP button

button (XA-920)

*FF button

POWER button

EJECT button

TV/VCR button

*REW button

REC button

TAPE SPEED button

*Numbered buttons

*PLAY button

*100, ENT. /AM/PM button

AUTO REPEAT button

CANCEL button

INPUT button

SLOW button

Inserting the Batteries

Make sure that the batteries have been properly installed first. Fit two batteries

• If the button is pressed while the light up buttons are illuminated,

they will remain illuminated for an additional seconds.

type "AA". If the remote control stops working, fit new batteries.

Ensure the batteries are fitted correctly, matching the polarities ( / ) indicated

in the remote control.

• After changing the batteries in the remote control, the code settings for the TV,

cable box and Digital Satellite Receiver must be re-entered.

• Do not subject the remote control to shock, water or excessive humidity.

• The remote control may not function if the VCR sensor is in direct sunlight or any other strong light.

• The operating life of the batteries will shorten if the Light Up function is frequently used.

• The operating life of the batteries will shorten if the Remote Pager function is frequently used.

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

• Do not mix old and new batteries, or mix brands in use.

• Remove the batteries if the remote control will not be operated for an extended period of time.

• If the remote control does not function properly when new batteries are installed, remove the batteries and keep pressing

any button for 10 seconds before re-installing them.

RENTAL REWIND button

CH (CHANNEL) '/" buttons

"/'/\/| button

VOL (VOLUME) / buttons

/ buttons (SLOW / ,

DPSS / )

• Press the button to illuminate

the light up buttons (indicated)

with the * mark) for 10

seconds.

XA-920

XA-905 XA-920

2. DISASSEMBLY AND REASSEMBLY

2-1. DISASSEMBLY OF MAJOR BLOCKS

TOP CABINET : Remove 2 screws 1. FRONT PANEL : Remove button 2.

Remove 2 screws 3 and 7 clips 4.

OPERATION : Remove 1 screw 5. PWB SHIELD ANGLE : Remove 1 screw 6 with shield angle. MECHANISM/ : Remove 1 screw 7, 1 screw 8, 2 MAIN PWB screws 9, 2 screws 0. Remove 1

screw q with antenna terminal cover. Remove 1 screw w with top cabinet fix angle.

ANTENNA TERMINAL COVER

XA-920

PAUSE JACK : Remove 3 screws e, 1 screw r, 2 PWB clips t with Pause Jack PWB and

Pause Jack cover. Disconnect earth lead and wire lead.

VIDEO JACK : Remove 2 screws y and disconnect PWB wire lead.

TOP CABINET

SHIELD ANGLE

ANTENNA TERMINAL COVER

XA-905

FRONT P ANEL

VIDEO JACK PWB

MECHANISM/ MAIN PWB ASSEMBLY

Except

( )

XA-905

XA-920

XA-905

PAUSE JACK PWB

MAIN FRAME

TOP CABINET FIX ANGLE

OPERATION PWB

2-2. DISASSEMBLING THE MECHANISM/MAIN PWB ASSEMBLY

XA-905 XA-920

1. When removing the mechanism from the main PWB, remove the antenna cover 1 screw 1, and remove the antenna cover. Remove the PWB bottom plate 1 screw 2. Remove the FFC cable (AA, AD, AH) 3 which connecting the PWB and the mechanism. Take out vertically the mechanism so that it does not damage the adjacent parts.

CASSETTE HOUSING

2. Removing the mechanism and cassette housing. Remove 2 screws 4 fixing the cassette housing to the mechanism, and remove the cassette housing.

MECHANISM CHASSIS

Except XA-905

MAIN PWB

XA-905 XA-920

2-3. CARES WHEN REASSEMBLING

INSTALLING THE CASSETTE HOUSING

When the cassette housing is installed on the mechanism, 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 (*1) install the

Pulley feed gear

Screwdriver

Tilt mark (*1)

cassette housing. (Conditions: When mechanism and PWB have been installed)

2. Mechanical initial setting

Feed the pulley feed gear of loading motor with screw driver. After ascertaining the return to the initial set position (*1) install the cassette housing in the specified position. (This method is applied only for the mechanism.)

Casecon drive gear

Drive angle of cassette housing

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

Except XA-905

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

START SENSOR

AL CONNECTOR

3. FUNCTION OF MAJOR MECHANICAL PARTS (TOP VIEW)

XA-905 XA-920

No. Function

1 Full erase head 2 Supply pole base ass’y 3 Tension arm 4 Idler wheel ass’y 5 Pinch drive lever ass’y 6 Supply reel disk 7 Supply main brake

No. Function

8 Take-up main brake

9 Pinch drive cam 10 A/C head ass’y 11 Reverse guide lever ass'y 12 Casecon drive gear 13 Take-up reel disk 14 Pinch roller lever ass’y

XA-905 XA-920

FUNCTION OF MAJOR MECHANICAL PARTS (BOTTOM VIEW)

19 20

No. Function

15 Drum ass’y 16 Loading motor 17 Drum drive motor 18 Take-up pole base ass’y 19 Slow brake lever 20 Master cam 21 Capstan D.D. motor

No. Function

22 Reel belt 23 Clutch lever 24 Limiter pulley ass'y 25 Shifter

XA-905 XA-920

4. ADJUSTMENT, REPLACEMENT AND ASSEMBLY OF MECHANICAL UNITS

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.

4-1. 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 use the required jig.

No. Jig ltem Part No. Code Configuration Remarks

This cassette torque meter is used for check-

1. Torque Cassette Meter JiGVHT-063 CZ

JiGTG0090 CM

Torque Gauge

JiGTG1200 CN

3. Torque Gauge Head JiGTH0006 AW

ing 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.

4. Torque Driver JiGTD1200 CB

Master Plane Jig and Reel Disk Height

5. Adjusting Jig

JiGRH0002 BR JiGMP0001 BY JiGSG2000 BS

Tension Gauge

JiGSG0300 BF

Pinch pressing force

7. JiGADP003 BK

measuring jig

Reverse guide height

adjustment box driver

Alignment Tape

JiGDRiVER11055

VROATSV CD

VROEFZCS

VROEFZHS

Guide roller height

10. JiGDRiVERH-4 AP

adjustment driver

When fixing any part to the threaded hole using resin with screw, use the jig. (Specified torque 5 kg)

These Jigs are used for checking and adjusting the reel disk height.

There are two gauges used for the tension measurements, 300 g and

2.0 kg. This Jig is used with the tension

gauge. Rotary transformer clearance adjusting jig.

This Jig is used for height adjustment of the reverse guide (for reverse guide height adjustment).

These tapes are especially used for electrical fine adjustment.

Video Audio HiFi Audio Track 525 Monoscope 7k — 58µm NTSC Color Bar 1k — 58µm

Black Level (only SYNC) signal

This screwdriver is used for adjusting the guide roller height.

—19µm

2.3k

X value adjustment

11. JiGDRiVER-6 BM gear driver

Reverse Guide Height

12. Adjusting Jig

JiGRVGH-F18

For X value adjustment

This Jig is used for height adjustment of the reverse guide.

XA-905 XA-920

4-2. MAINTENANCE CHECK ITEMS AND EXECUTION TIME

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

Maintained

Parts

Guide roller ass’y Sup guide shaft Reverse guide Slant pole on pole base Full erase head A/C head

Upper and lower drum ass’y

Capstan D.D. motor Pinch roller

Reel belt

500 hrs.

1000 hrs.

1500 hrs.

2000 hrs.

Possible symptom

encountered

Lateral noises Head occasionally blocked

Colour and beating Small sound or sound

distortion Poor S/N ratio, no colour

Poor flatness of the envelope with alignment tape

No tape running, uneven colour

No tape running, tape slack

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

Remarks

Abnormal rotation or significant vibration requires replacement.

Clean tape contact part with the specified cleaning liquid.

Clean tape contact area with the specified cleaning liquid.

Clean rubber and rubber contact area with the specified cleaning liquid.

Tension band ass’y Loading motor

Idler ass’y Limiter pulley Supply/take-up main brake levers

Screen swaying Cassette not loaded or

unloaded No tape running, tape

slack

Tape slack

Replace the roller of the cleaner

AHC (Automatic Head Cleaner) (XA-920)

when it wears down. Just change the AHC roller assembly for new one.

NOTE : Part replacement. : Cleaning : Apply grease <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.

Video head cleaning procedure

1. Apply one drop of cleaning liquid to the cleaning paper with the baby oiler.

2. Gently press the cleaning paper against the video head to fix your finger, and move the upper drum so that each head is passed to and fro 5 times (do not move the cleaning paper).

3. Wipe with the dry cleaning paper.

Notes :

• Use the commercially available ethanol of Class 1 as cleaning liquid.

• Since the video head may be damaged, do not move up and down the cleaning paper.

Gently press the cleaning paper to fix with your finger, and rotate the upper drum to clean. Move to and fro 5 times for each head. (Do not move the cleaning paper.)

Rotate the upper drum with one hand.

• Whenever the video head is cleaned, replace the cleaning paper.

• Do not apply this procedure for the parts other than the video head.

Parts Code Description Code ZPAPRA56-001E Cleaning Paper AW ZOiLR-02-24TE Babe Oiler (Spoit) AH

XA-905 XA-920

4-3. REMOVING AND INSTALLING THE CAS-

SETTE HOUSING

• 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 1. b) Slide and pull up the cassette housing control.

Notes:

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

2. Misengagement of teeth of casecon drive gear and drive angle gear causes malfunction. (The cassette cannot be set, load and ejection are repeated).

3. In the case when you use the magnet screw driver, never approach the magnet driver to the A/C head, FE head, and drum.

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

5. After installing the cassette housing control once perform cassette loading operation.

4-4 . TO RUN A TAPE WITHOUT THE CAS-

SETTE HOUSING CONTROL ASSEMBLY

1. Remove the full-surface panel.

2. Short-circuit TP803 and TP802.

3. Plug in the power cord.

4. Turn off the power switch.

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

5. Open the lid of a cassette tape by hand.

6. Hold the lid with two pieces of vinyl tape.

7. Set the cassette tape in the mechanism chassis.

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

prevent floating.

9. Turn on the power switch.

10. Perform running test.

Figure 4-1.

• Reassembly

1. Before installing the cassette housing control, shortcircuit TP803 and TP802 provided at operation 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 drive gear

Casecon drive angle gear

500g

Weight to prevent float (500g)

Mechanism chassis

Figure 4-3.

Note:

The weight should not be more than 500g. To take out the cassette tape.

1. Turn off the power switch.

2. Take out the cassette tape.

Figure 4-2.

2. Install in the reverse order of removal.

XA-905 XA-920

4-5. REEL DISK REPLACEMENT AND

HEIGHT CHECK

• Removal

1. Remove the cassette housing control assembly.

2. Pull the tension band out of the tension arm ass'y.

3. Remove the Supply/Take-up main brake ass'y.

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

Supply main brake ass'y

Tension band ass'y

Supply reel disk

Take-up main brake ass'y

Take-up reel disk

4. Assemble the Supply main brake ass'y.

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.

2. Do not damage the Supply main brake ass'y. Be careful so that grease does not adhere to the brake surface.

• Reassembly (Take-up reel disk)

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

2. 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.

3. Check the reel disk height and reassemble the take-up main brake ass'y.

Note:

1. Take care so that the Take-up 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 4-10), and check the brake torque (see 4-

14).

• Height checking and adjustment Note:

1. 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 ass'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)

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

2. Match the phases of reel disk and reel relay gear, and set the new reel disk.

3. After checking the reel disk height, wind the tension band ass'y around the reel disk, and insert into the hole of tension arm ass'y.

Master plane

Reverse guide

Supply reel disk

Cassette lock release shaft

Take-up reel disk

Position pin

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.

XA-905 XA-920

Note:

Whenever replacing the reel disk, perform the height checking and adjustment.

Master plane

10 ± 0.2mm

Reel disk

Reel disk height adjusting jig

Mechanism chassis

Figure 4-7.

4-6. CHECKING AND ADJUSTMENT OF

TAKE-UP TORQUE IN FAST FORWARD MODE

• Remove the cassette housing control assembly.

• After short-circuiting TP803 and TP802 provided at operation PWB, plug in the power cord.

• Setting

1. Set a torque gauge to zero on the scale. Place it on the take-up reel disk.

2. Press the FF button.

3. 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

1. Turn the torque gauge slowly (one rotation every 2 to 3 seconds) by hand in the CW direction.

Torque gauge

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 longtime measurement.

4-7. CHECKING AND ADJUSTMENT OF

TAKE-UP TORQUE IN REWIND MODE

• Remove the cassette housing control assembly.

• After short-circuiting TP803 and TP802 provided at operation PWB, plug in the power cord.

• Setting

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

2. Press the rewind button.

3. To calculate the remaining capacity, slowly rotate the take-up reel disk, and then shift it into the rewind mode.

• Checking

1. Turn the torque gauge slowly (one rotation every 2 to 3 seconds) by hand in the CCW direction.

2. Make sure that the indication of torque gauge is not less than 30mN·m (306gf·cm).

Torque gauge

30mN·m (306gf·cm) or more

CCW

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

30mN·m (306gf·cm) or more

Idler ass'y

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

Figure 4-8.

2. Make sure that the indication of torque gauge is not less than 30mN·m (306gf·cm).

• Adjustment

1. 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 than the set value, replace the reel belt.

Supply reel disk

Idler ass'y

Figure 4-9.

• Adjustment

1. 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.

XA-905 XA-920

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 longtime measurement.

4-8. CHECKING AND ADJUSTMENT OF TAKE-

UP TORQUE IN RECORD/PLAYBACK MODE

• Remove the cassette housing control assembly.

• After short-circuiting TP803 and TP802 provided at operation 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.

Set value EP6.9 ± 2.5mN⋅m (70 ± 25gf⋅cm)

4-9. CHECKING AND ADJUSTMENT OF

TAKE-UP TORQUE IN VIDEO SEARCH REWIND MODE

• Remove the cassette housing control assembly.

• After short-circuiting TP803 and TP802 provided at operation PWB, plug in the power cord.

• Setting

Press the playback button and rewind button to set the video search rewinding mode.

• Checking

Place the torque gauge on the supply reel disk, and turn it counterclockwise very slowly (one rotation every 1 to 2 seconds) and check that the torque is within the set value

14.0 ± 3.9mN⋅m. (144 ± 40gf⋅cm)

Torque gauge

CCW

500g

Cassette torque meter

Figure 4-10.

• Press the picture record button, and set EP picture record mode (x3).

• Checking

1. Make sure that value is within the setting 6.9 ± 2.5mN·m (70 ± 25gf·cm).

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.

3. Set the EP record mode (x3) and make sure that the winding-up torque is within setting.

• Adjustment

If 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.

• Adjustment

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.

4-10. CHECKING THE VIDEO SEARCH

REWIND BACK TENSION

• Remove the cassette housing control assembly.

XA-905 XA-920

• After short-circuiting TP803 and TP802 provided at operation PWB, plug in the power cord.

• Checking

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

2. 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 ± 15gf⋅cm).

Torque gauge

CCW

Take-up reel disk

Pinch roller

Capstan shaft

Tension gauge adapter

Tension gauge 900 - 1,200gf

Figure 4-13.

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

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

3. Gradually return the pinch roller, and measure the pulling force when the pinch roller contacts the capstan shaft.

4. Make sure that the measured value is within setting 9.0 N to 11.8 N (900 to 1,200gf).

Figure 4-12.

Notes:

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

4-11. CHECKING THE PINCH ROLLER

PRESSURE

• Remove the cassette housing control assembly.

• After short-circuiting TP803 and TP802 provided at operation PWB, plug in the power cord.

• Checking

Press the play button to set the playback mode.

4-12. CHECKING AND ADJUSTMENT OF

TENSION POLE POSITION

• Remove the cassette housing control assembly.

• After short-circuiting TP803 and TP802 provided at operation PWB, plug in the power cord.

• 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 (500g) on the cassette tape.

5. Turn on the power switch.

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

(T-120)

500g

Weight to prevent float (500g)

Figure 4-14.

• Checking

1. Set a cassette tape, push the REC button to place the unit in the SP record mode. Now check the tension pole position.

XA-905 XA-920

2. Visually check to see if the right edge of the tension pole is within the 2.3 ± 0.25 from the right edge of the Sup guide shaft.

Sup guide shaft

Tension pole

2.3 ± 0.25

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 adjuster

90°

Figure 4-18.

Adjust so that the delta mark of tension pole adjuster is within 90° range (left, right).

4-13. CHECKING AND ADJUSTMENT OF

RECORD/PLAYBACK BACK TENSION

• Remove the cassette housing control assembly.

2.3 ± 0.25

Figure 4-16.

Insert the slotted screwdriver in the tension pole adjuster, and rotate counterclockwise.

At right side from the center line

2.3 ± 0.25

Figure 4-17.

Insert the slotted screwdriver in the tension pole adjuster, and rotate clockwise.

• After short-circuiting TP803 and TP802 provided at operation PWB, plug in the power cord.

• Setting

1. Turn off the power switch.

2. Open the torque cassette meter and fix with tape.

3. Set the cassette tape in loading state.

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

5. Turn on the power switch.

500g

Weight to prevent float (500g)

Cassette torque meter

Figure 4-19.

• Checking

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

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

XA-905 XA-920

• 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 B.

Tension arm

Tension spring

Figure 4-20.

4-14. CHECKING THE BRAKE TORQUE

• Checking the brake torque at the supply side

Torque gauge

CCW

• Checking the brake torque at the take-up side

Torque gauge

Take-up reel disk

CCW: 4.9~13.7mN⋅m (50~140gf⋅cm) CW: 3.9~10.8mN⋅m (40~110gf⋅cm)

CCW

Figure 4-22.

• Remove the cassette housing control assembly.

• After short-circuiting TP803 and TP802 provided at operation PWB, plug in the power cord.

Supply reel disk

CCW: 2.9~9.8mN⋅m (30~100gf⋅cm) CW: 4.9~13.7mN⋅m (50~140gf⋅cm)

Figure 4-21.

• Remove the cassette housing control assembly.

• After short-circuiting TP803 and TP802 provided at operation PWB, plug in the power cord.

• Setting

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

2. Switch from the FF mode to the STOP mode.

3. Disconnect the power cord.

• Checking

Turn the torque gauge at a rate of about one turn/2 sec 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: 4.9 to 13.7mN·m (50 to 140gf·cm); CCW direction: 2.9 to 9.8mN·m (30 to 100gf·cm).

• Setting

1. 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

1. Turn the torque gauge at a rate of about one turn/2 sec 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: 4.9 to 13.7mN·m (50 to 140gf·cm), CW direction: 3.9 to 10.8 mN·m (40 to 110gf·cm).

2. 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-905 XA-920

4-15. REPLACEMENT OF A/C (Audio/Control)

HEAD

1. Remove the cassette housing control assembly.

2. In unloading state unplug the power cord.

• Removal

1. Remove the screws 123, Azimuth screw, Tilt screw.

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

Notes:

1. When replacing, never touch the head. If you touched, clean with the cleaning liquid.

2. When removing the screw 3, take care so that the spring may out.

Tilt screw

Azimuth screw

Height screw

Spring

3. Align the left end of gear of A/C head arm with the punched mark of chassis, tentatively tighten the screws 1 and 2 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 2.0kgf·cm).

Height screw

Left end of A/C head arm gear

Punched line mark on chassis

Figure 4-25.

Note:

1. If the screws 1 and 2 are tighten tentatively too loose, the azimuth and height of A/C head may change when they are finally tightened. Therefore care must be taken.

2. After completion of A/C head be sure to adjust tape running. (Execute the running adjustment by the method described in 4-18.)

Figure 4-23.

• Replacement

1. 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

New A/C head ass'y

A/C head PWB

Never touch the head

A/C head plate

Figure 4-24.

10.8mm10.8mm

XA-905 XA-920

4-16. A/C HEAD HEIGHT ROUGH AD-

JUSTMENT

Azimuth screw

Height screw

500g

Weight to prevent float (500g)

• Setting

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

Tilt screw

Cassette tape

Mechanism chassis

Figure 4-26.

4-17. HEIGHT ADJUSTMENT OF REVERSE

GUIDE

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 Reverse guide height adjusting jig

Mechanism chassis

(a)

Figure 4-28.

2. Rotate counterclockwise the reverse guide height adjustment nut 1/10 turn. (For height adjustment use the reverse guide height adjustment box driver (JiGDRiVER

11055)).

CCW

Reverse guide height adjusting jig

13.38mm

(b)

Box driver

Height adjusting nut

Tape

0.3mm

Figure 4-27.

• Adjustment

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

Figure 4-29.

3. 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.)

500g

Weight to prevent float (500g)

Mechanism chassis

Reverse guide

Capstan motor shaft

Fixing guide

An example of crease near the reverse guide

* Check for crease from the A direction.

Figure 4-30.

XA-905 XA-920

4-18. ADJUSTMENT OF TAPE DRIVE TRAIN

1. Tape run rough adjustment

1 Remove the cassette housing control assembly. 2 After shortcircuiting TP803 and TP802 provided at

operation PWB, plug in the power cord.

3 Check and adjust the position of the tension pole.

(See 4-12.)

4 Check and adjust the video search rewind back

tension. (See 4-10.)

5 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).

6 Set the alignment tape (VROATSV) to play. (Put a

500g weight on the cassette tape to prevent lift of cassette tape.)

Guide roller

Cassette Tape

500g

Weight of 500g

Figure 4-31.

7 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.

8 Unless the envelope waveform changes nearly par-

allel, adjust the height of supply side and take-up side guide roller so that the envelope waveform changes nearly parallel. (For envelop adjustment procedure refer to Figure 4-35.)

9 Turn the tilt screw to remove the tape crease at the

fixing guide flange. Playback 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.

Notes:

1. 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.

2. Especially the outlet side envelope waveform must have higher flatness.

Figure 4-32.

2. Adjustment of A/C head height and azimuth 1 Perform the initial setting of A/C head position by the

method stated in "4-15 Replacement 3".

2 Connect the oscilloscope to the audio output termi-

nal.

3 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.

4 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.

5 The adjustment of 3 and 4 twice or three times

repeat, and finally adjust 4.

For X value adjustment Adjust the X value, turning the geartype screwdriver.

Figure 4-33.

3. Tape run adjustment 1 Connect the oscilloscope to PB CHROMA envelope

output test point, set oscilloscope sync to EXT, trigger-input the PB CHROMA signal (head switching pulse).

2 Rough adjustment of X value

Tentatively fix A/C head arm screws 1 and 2 by the method described in 4-15 "Replacement 3". Playback the alignment tape (VROATSV) and shortcircuit TP801 and TP802. As a result the autotracking 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 4-15.)

3 Next, Press the tracking button (+), (–) and change

CH-1 CH-2

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.

4 If the tape is lifted or sunk from the helical lead

surface, the PB CHROMA envelope waveform appears as shown in Figure 4-35.

5 Press the tracking button (+), (–) and make sure that

the envelope waveform changes nearly parallel.

6 Finally check tape crease near the reverse guide. If

tape crease is found, remove it as stated in 4-17 "HEIGHT ADJUSTMENT OF REVERSE GUIDE" item 3.

Supply side

Take-up side Supply side Take-up side

XA-905 XA-920

PB CHROMA Envelope

Head switching pulse

Figure 4-34.

4. A/C head X value adjustment 1 Tentatively fix A/C head arm screws 1 and 2 by the

method described in 4-15 "Replacement 3".

2 Playback the alignment tape (VROATSV), and

shortcircuit TP801 and TP802. As a result the autotracking is automatically cancelled, so that the X value adjustment mode is set.

When the tape is below the helical lead.When the tape is above the helical lead.

Adjustment

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

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

Figure 4-35.

3 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 4-18, 3- 2.)

4 Tighten finally the screws 1 and 2. Be sure to

tighten at first the screw 1 and then the screw 2. Final tightening torque is 0.6N·m (If the screw 2 is tightened first, the X value may deviate.)

5 Adjust the playback switching point (Refer to the

electric adjustment method.)

6 Playback the self-picture-recorded tape, and check

the flatness of envelope waveform and sound.

Supply side guide roller rotated in counterclockwise direction (raises guide roller) to make the tape float above the helical lead. The supply side guide roller is then rotated in the clockwise direction to flatten the envelope.

Take-up side guide roller rotated in counterclockwise direction (raises guide roller) to make the tape float above the helical lead. The take-up side guide roller is then rotated in the clockwise direction to flatten the envelope.

Notes:

When the A/C head X value adjustment is performed, be sure to perform at first X value rough adjustment (refer to 4- 18, 3-2).

Figure 4-36.

XA-905 XA-920

4-19. REPLACEMENT OF THE CAPSTAN D.D.

(DIRECT DRIVE) MOTOR

• Remove the mechanism from the main PWB (refer to 22 "item 1 When removing the mechanism from the main

PWB").

• Removal (Follow the order of indicated numbers.)

1. Remove the reel belt 1.

2. Remove the slow brake lever 2.

3. Remove the three screws 3.

Capstan D.D. motor

Capstan D.D. motor control PWB

4-20. 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 1.

2. Unscrew the D.D. stator assembly fixing screws 2.

3. Take out the D.D. stator assembly 3.

4. Unscrew the D.D. rotor assembly fixing screws 4.

5. Take out the D.D. rotor assembly 5.

Notes:

1. 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.

2. 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.)

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

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

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

Reel belt

Slow Brake lever

Figure 4-37-1.

• Reassembly

1. 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 slow brake lever.

3. Install the reel belt.

Notes:

1. Before installing the capstan D.D. motor, confirm whether an acetate tape ZTAPEN120020E is drawn on the back of mechanism chassis.

Stick an acetate tape on the projection part of the chassis.

Capstan Motor Installation position.

Mechanism Chassis from the back.

D.D. stator ass'y

D.D. rotor ass'y

FFC

Upper drum

Figure 4-38.

Figure 4-37-2.

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

3. 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 4-18 item 2. If crease is found, adjust as stated in 4-17 "HEIGHT ADJUSTMENT OF REVERSE GUIDE".

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SHARP XA-905, XA-920 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual