Sharp XA-920 User manual

1
XA-905
XA-920
S80E5XA-905//
SERVICE MANUAL
This document has been published to be used for
after sales service only.
Thecontentsaresubjecttochangewithoutnotice.
SHARP CORPORATION
CONTENTS
In the interests of user-safety (Required by safety regula-
tions in some countries) the set should be restored to its
originalconditionandonlypartsidenticaltothosespecified
be used.
MODELS
Page
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
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
XA-905
XA-905
XA-920
PROFESSIONAL SERIES
VIDEO CASSETTE RECORDER
XA-905
XA-920
SERVICE MANUAL ROFESSIONAL SERIES VIDEO CASETTE RECORDER
MODELS XA-905/XA-920

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XA-905
XA-920
IMPORTANT SERVICE NOTES
WARNING :TOREDUCETHERISKOFFIREORELEC-
TRIC SHOCK, DO NOT EXPOSE THIS AP-
PLIANCE TO RAIN OR MOISTURE.
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK. DO
NOT REMOVE COVER. NO USER-SERVICEABLE
PARTS INSIDE. REFER SERVICING TO QUALIFIED
SERVICE PERSONNEL.
This symbol warns the user of uninsulated voltage
withintheunitthatcancausedangerouselectricshocks.
This symbol alerts the user that there are important
operatingandmaintenanceinstructionsintheliterature
accompanying this unit.
This symbol mark means fast operating fuse.
For continued protection against risk of fire, replace
only with same type fuse F901 (3.0A, 125V).
CAUTION:
BEFORE RETURNING THE VIDEO CASSETTE
RECORDER
Beforereturning thevideo cassetterecorder tothe user,
perform the following safety checks.
1. Inspect all lead dress to make certain that leads are
not pinched or that hardware is not lodged between
thechassisandothermetalpartsinthevideocassette
recorder.
2. Inspect all protective devices such as non-metallic
control knobs, insulation materials, cabinet backs,
adjustmentandcompartmentcoversorshields,isola-
tion resistor/capacitor networks, mechanical insula-
tors etc.
3. To be sure that no shock hazard exists, check for
current in the following manner.
●Plug the AC line cord directly into a 120 volt AC outlet
(Do not use an isolation transformer for this test).
●Using two clip leads, connect a 1.5k ohm, 10 watt
resistorparalleledbya0.15µFcapacitorinserieswith
all exposed metal cabinet parts and a known earth
ground, such as a water pipe or conduit.
●Use an SSVM or VOM with 1000 ohm per volt, or
higher, sensitivity or measure the AC voltage drop
across the resistor (See Diagram).
●Move the resistor connection to earth exposed metal
part having a return path to the chassis (antenna,
metalcabinet,screwheads,knobsandcontrolshafts,
SSVM
AC SCALE
1.5k ohms.
10W
CONNECT TO
KNOWN EARTH
GROUND
TO EXPOSED
METAL PARTS
0.15 µF
TEST PROBE
etc.) and measure the AC voltage drop across the
resistor. Reverse the AC plug on the set and repeat
AC voltage measurements for each exposed part.
Anyreading of 0.45Vrms (thiscorresponds to 0.3mA
rms AC.) or more is excessive and indicates a poten-
tial shock hazard which must be corrected before
returning the video cassette recorder to the owner.
3.0A 125V

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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.

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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
•19
µClear Picture System (in EP mode)
• HQ System for Better Resolution and Color Reproduction
• Multi-Language(English/Spanish/French)OSD(OnScreen
Display) with Menu Screen Guidance
• 181-channelPLLQuartzSynthesizedRandomAccessTuner
with Automatic Channel Setting
• Quick Start with Full Loading Mechanism
• 1-Year, 8-Event Programmable Timer
• Simple Recording Timer
• 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
2 Rotary Heads for Hi-Fi stereo (Only Hi-Fi model)
Tape Width: 12.7 mm (1/2 inch)
Tape Speed: (SP) 33.35 mm/sec (1.31 i.p.s.)
(LP) 16.67 mm/sec (0.66 i.p.s.) (playback only)
(EP) 11.12 mm/sec (0.44 i.p.s.)
Maximum Recording Time: (SP) 160 min (T-160)
(EP) 480 min (T-160)
Channel Coverage: VHF 2-13
UHF 14-69
CATV 1-125
Antenna Input: 75 Ohm
Video Input: 0.5 to 2.0 Vp-p, 75 Ohm unbalanced
Video Output: 1.0 Vp-p, 75 Ohm unbalanced
Audio Input: –8 dBs, 47 kOhm unbalanced (0 dBs = 0.775 Vrms)
Audio Output: –8 dBs, 1 kOhm unbalanced (0 dBs = 0.775 Vrms)
Hi-Fi Audio (Only for Hi-Fi model): Dynamic Range: 90 dB
Frequency Response: 20 Hz-20 kHz
Memory Backup: 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)
360 (W) x 92.5 (H) x 263.5 (D) mm (14-3/16" x 3-41/64" x 10-3/8") (XA-920)
Weight (approx.): 2.8 kg (6.2 lbs)
Accessories included: 75 ohm coaxial cable, Operation manual, Infrared remote control, Battery (2 pcs.),
Warranty Card
Note: Specifications are subject to change without notice.

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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 ofYourVCR
[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
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)
(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

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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 3and 7 clips 4.
OPERATION : Remove 1 screw 5.
PWB
SHIELD ANGLE : Remove 1 screw 6with shield angle.
MECHANISM/ : Remove 1 screw 7, 1 screw 8, 2
MAIN PWB screws 9, 2 screws 0. Remove 1
screwqwithantennaterminalcover.
Remove 1 screw wwith top cabinet
fix angle.
PAUSE JACK : Remove 3 screws e, 1 screw r, 2
PWB clips twith Pause Jack PWB and
Pause Jack cover.
Disconnect earth lead and wire lead.
VIDEO JACK : Remove 2 screws yand disconnect
PWB wire lead.
B
C
A
B
5
9
6
10
11
7
8
3
3
C
1
12
2
4
XA-920
XA-905
XA-920
XA-905
Except
XA-905
11
A
2
4
VIDEO JACK PWB
PAUSE JACK PWB
13
14
15
16
( )
TOP CABINET
SHIELD
ANGLE
ANTENNA
TERMINAL
COVER
ANTENNA
TERMINAL
COVER
MECHANISM/
MAIN PWB ASSEMBLY
FRONT PANEL
FRONT PANEL
OPERATION PWB
TOP CABINET
FIX ANGLE
MAIN FRAME

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XA-905
XA-920
Except XA-905
MECHANISM CHASSIS
2-2. DISASSEMBLING THE MECHANISM/MAIN PWB ASSEMBLY
1. When removing the mechanism from the main PWB,
remove the antenna cover 1 screw 1, and remove the
antenna cover.
Remove the PWB bottom plate 1 screw 2.
RemovetheFFCcable(AA,AD,AH)3whichconnect-
ing the PWB and the mechanism.
Take out vertically the mechanism so that it does not
damage the adjacent parts.
2. Removing the mechanism and cassette housing.
Remove 2 screws 4fixing the cassette housing to the
mechanism, and remove the cassette housing.
2
1
3
4
CASSETTE
HOUSING
MAIN PWB

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XA-905
XA-920
Except XA-905
START SENSOR
2-3. CARES WHEN REASSEMBLING
INSTALLING THE CASSETTE HOUSING
When the cassette housing is installed on the mechanism,
the initial setting is essential condition.
Therearetwoinitialsettingmethods,namelyelectricaland
mechanical.
1. Electrical initial setting
So as to perform initial setting of mechanism execute the
Step1ofInstallationofcassettehousing.Afterascertaining
the return to the initial setting position (*1) install the
cassettehousing.(Conditions:WhenmechanismandPWB
have been installed)
2. Mechanical initial setting
Feed the pulley feed gear of loading motor with screw
driver.Afterascertainingthereturntotheinitialsetposition
(*1) install the cassette housing in the specified position.
(This method is applied only for the mechanism.)
INSTALLING THE MECHANISM ON PWB
Lower vertically the mechanism, paying attention to the
mechanismedge,andinstallthemechanismwithduecare
so that the parts are not damaged. So as to fix the mecha-
nismtothemainPWBinstalltwohousings.(Fittheantenna
cover to one of them. For other, fix the vicinity of loading
motor and solder joint side of main PWB.) Connect again
the FFC cable (AA-MH, AD-ME, AH-MH) between the
mechanism and the main PWB.
PARTS WHICH NEED PARTICULAR CARE
When installing the mechanism chassis on the PWB unit,
take care so as to prevent deformation due to contact of
mechanism chassis with REC TIP SW.
Pulley feed gear
Screwdriver
AE CONNECTOR
AL CONNECTOR
Casecon
drive gear
Drive angle of
cassette housing
END SENSOR
AC CONNECTOR
Tilt mark (*1)
REC TIP SW

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

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XA-920
FUNCTION OF MAJOR MECHANICAL PARTS (BOTTOMVIEW)
No. Function No. Function
15 Drum ass’y
16 Loading motor
17 Drum drive motor
18 Take-up pole base ass’y
19 Slow brake lever
20 Master cam
21 Capstan D.D. motor
22 Reel belt
23 Clutch lever
24 Limiter pulley ass'y
25 Shifter
25
24
21
22
19
20
12
23

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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.
JiGTG1200 CN
JiGMP0001 BY
1. Torque Cassette Meter JiGVHT-063 CZ
No. Jig ltem Part No. Code Configuration Remarks
JiGTG0090 CM
3. Torque Gauge Head JiGTH0006 AW
JiGRH0002 BR
JiGSG2000 BS
JiGSG0300 BF
7. JiGADP003 BK
Tension Gauge
These Jigs are used for checking
and adjusting the reel disk height.
Whenfixinganyparttothethreaded
hole using resin with screw, use the
jig. (Specified torque 5 kg)
Thiscassettetorquemeterisusedforcheck-
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.
Master Plane Jig and
Reel Disk Height
Adjusting Jig
Pinch pressing force
measuring jig
This Jig is used with the tension
gauge.Rotarytransformerclearance
adjusting jig.
There are two gauges used for the
tension measurements, 300 g and
2.0 kg.
4. Torque Driver JiGTD1200 CB
8. JiGDRiVER11055 AR
Reverse guide height
adjustment box driver This Jig is used for height adjustment of the
reverse guide (for reverse guide height ad-
justment).
Thesetapes are especially used for
electrical fine adjustment.
Video Audio HiFi Audio Track
525 Monoscope 7k — 58µm
NTSC Color Bar 1k — 58µm
2. Torque Gauge
6.
5.
VROATSV CD
9. Alignment Tape
BG
BH
VROEFZCS
or
VROEFZHS
Black Level
(only SYNC) signal
—19µm
1k
2.3k
This screwdriver is used for adjusting the
guide roller height.
Guide roller height
adjustment driver
X value adjustment
gear driver
10. JiGDRiVERH-4 AP
Reverse Guide Height
Adjusting Jig
For X value adjustment
This Jig is used for height
adjustment of the reverse guide.
BU
11. JiGDRiVER-6 BM
12. JiGRVGH-F18

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XA-920
Perform the maintenance with the regular intervals as follows so as to maintain the quality of machine.
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.
Maintained
Parts Remarks
500
hrs. 1000 hrs. 1500 hrs. 2000 hrs. Possible symptom
encountered
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
Tension band ass’y
Loading motor
Idler ass’y
Limiter pulley
Supply/take-up main brake levers
AHC (Automatic Head Cleaner)
(XA-920)
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
Lateral noises Head
occasionally blocked
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.
Replace the roller of the cleaner
when it wears down.
Just change the AHC roller
assembly for new one.
Screen swaying
Cassette not loaded or
unloaded
No tape running, tape
slack
Tape slack
4-2. MAINTENANCE CHECK ITEMS AND EXECUTION TIME
Video head cleaning procedure
1. Apply one drop of cleaning liquid to the cleaning paper with the baby oiler.
2. Gentlypressthecleaningpaperagainst the videoheadtofixyourfinger,andmovetheupperdrum so thateachhead
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.
• Whenever the video head is cleaned, replace the clean-
ing 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
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.

13
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XA-920
Figure 4-1.
• Reassembly
1. Before installing the cassette housing control, short-
circuit TP803 and TP802 provided at operation PWB,
presstheejectbutton.Thecasecondrivegearturnsand
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.
Figure 4-2.
2. Install in the reverse order of removal.
Notes:
1. When fitting the S/E sensor holder to the cassette
controller frame L/R, take care.
2. Misengagementofteethofcasecondrivegearanddrive
anglegearcausesmalfunction.(Thecassettecannotbe
set, load and ejection are repeated).
3. Inthecasewhenyouusethemagnetscrewdriver,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 per-
form 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.
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.
1
Casecon
drive gear Casecon drive
angle gear
500g
Figure 4-3.
Mechanism chassis
Weighttoprevent
float (500g)
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.

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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. Openthehookatthetopofthereeldisk,andremovethe
reel disk.
Note:
Take care so that the tension band ass'y and main brake
ass'y (especially soft brake) are not deformed.
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. Donot damagethe Supplymain brakeass'y. Becareful
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
gearandtoinstallanewtake-upreeldiskontotheshaft.
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.Takecaresothatgreasedoesnotadherethe
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
alittleintheloading direction. Care mustbetakensince
excessive shift results in damage.
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
diskheightbychangingthepoly-sliderwasherunderthe
reel disk.
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. Matchthephasesofreeldiskandreelrelaygear,andset
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.
Tension arm ass'y
Supply reel disk Take-up reel disk
Master plane
Reverse
guide
Position
pin
Supply reel disk
Cassette lock
release shaft
Take-up reel disk
Tension band ass'y
Supply main brake ass'y
Take-up main brake ass'y

15
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XA-920
Note:
Wheneverreplacingthereeldisk,performtheheightcheck-
ing and adjustment.
Notes:
1. Hold the torque gauge by hand so that it is not moved.
2. Donotkeepthereeldiskinlockstate.Donotallowlong-
time 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. Makesurethatthe indication of torquegaugeis not less
than 30mN·m (306gf·cm).
AB
Figure 4-7.
Master plane Reel disk height
adjusting jig
Mechanism chassis
Reel disk
10 ±0.2mm Reel disk
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.
Figure 4-9.
Torque gauge
30mN·m (306gf·cm)
or more
Supply reel disk
Idler ass'y
The gauge is held at
its maximum value.
(Red mark)
• Adjustment
1. Iftherewindwinding-uptorqueislessthanthespecified
value, clean the capstan D.D. motor pulley, drive belt,
andlimiterpulleywith cleaning liquid, rewindagain,and
check the winding-up torque.
2. If the winding-up torque is still out of range, replace the
drive belt.
Figure 4-8.
Torque gauge
30mN·m (306gf·cm)
or more
The gauge is held at
its maximum value.
(Red mark)
Idler ass'y
2. Makesurethatthe indication of torquegaugeis 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.
CCW
CW

16
XA-905
XA-920
Notes:
1. Hold the torque gauge by hand so that it is not moved.
2. Donotkeepthereeldiskinlockstate.Donotallowlong-
time 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.
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
Iftherewindingplaybackwinding-uptorqueisnotwithinthe
setting, replace the limiter pulley assembly.
Note:
The winding-up torque fluctuates due to variation of rota-
tion torque of supply reel disk. Read the center value of
fluctuation as setting.
Set value EP6.9 ±2.5mN⋅m (70 ±25gf⋅cm)
500g
Cassette torque meter
Figure 4-10.
• Press the picture record button, and set EP picture
record mode (x3).
• Checking
1. Makesurethatvalueiswithinthesetting 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.
Torque gauge
Supply reel disk
CCW
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)

17
XA-905
XA-920
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).
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. MaketheadjustmentwiththebeginningofaT-120tape.
4-10. CHECKING THE VIDEO SEARCH
REWIND BACK TENSION
• Remove the cassette housing control assembly.
• 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. Placethetorquegaugeonthetake-upreeldisk,andturn
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).
Pinch roller Tension gauge
900 - 1,200gf
Capstan shaft
Tension gauge adapter
Figure 4-12.
Torque gauge
Take-up reel disk
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.
CCW
Figure 4-14.
500g
(T-120)
Weight to prevent
float (500g)
• 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.

18
XA-905
XA-920
2. Visuallychecktoseeif therightedgeofthetensionpole
is within the 2.3 ±0.25 from the right edge of the Sup
guide shaft.
Insert the slotted screwdriver in the tension pole adjuster,
and rotate clockwise.
Figure 4-17.
At left side from the center line
Figure 4-15.
Figure 4-16.
Insert the slotted screwdriver in the tension pole adjuster,
and rotate counterclockwise.
At right side from the center line
Tension pole adjuster adjusting range
2.3 ±0.25
2.3 ±0.25
2.3 ±0.25
Sup guide shaft
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.
• 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.
Make the adjustment with the beginning of a T-120 tape.
Tension pole adjuster
90°
90°
Figure 4-18.
Tension pole
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.

19
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.
• Checking the brake torque at the take-up side
Figure 4-22.
CCW: 4.9~13.7mN⋅m (50~140gf⋅cm)
CW: 3.9~10.8mN⋅m (40~110gf⋅cm)
• Remove the cassette housing control assembly.
• After short-circuiting TP803 and TP802 provided at
operation PWB, plug in the power cord.
• 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 direc-
tion: 3.9 to 10.8 mN·m (40 to 110gf·cm).
2. Adjustmentofthebraketorqueatthesupplysideandthe
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.
Figure 4-20.
4-14. CHECKING THE BRAKE TORQUE
• Checking the brake torque at the supply side
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
valueiswithinthesetting(CWdirection:4.9to13.7mN·m
(50 to 140gf·cm); CCW direction: 2.9 to 9.8mN·m (30 to
100gf·cm).
Tension arm
Tension spring
CW
CCW CW
Supply reel disk
Torque gauge
Torque gauge
CCW
Take-up reel
disk
AB

20
XA-905
XA-920
Figure 4-24.
• Replacement
1. Solder the removed PWB to the new head assembly.
2. AdjusttheheightfromtheA/Cheadarm(lower surface)
to the A/C head plate to 10.8mm with slide calipers. (3
placesofazimuthscrewsection,tiltscrewsectionandA/
C head front section) (See the figure below.)
3. Align the left end of gear of A/C head arm with the
punched mark of chassis, tentatively tighten the screws
1and 2so 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).
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. Removethescrews123,Azimuthscrew,Tiltscrew.
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.
New A/C head ass'y
A/C head PWB
2
Spring 1
Solder
Never touch the head
10.8mm10.8mm
Azimuth screw
Height screw
Tilt screw
A/C head plate
Figure 4-25.
Note:
1. Ifthescrews1and2aretightententativelytooloose,
the azimuth and height of A/C head may change when
theyarefinallytightened. Thereforecaremustbetaken.
2. After completion of A/C head be sure to adjust tape
running.(Executetherunningadjustmentbythemethod
described in 4-18.)
1
2
3
Height screw
Figure 4-23.
3
Left end of A/C head arm gear
Punched line mark on chassis