VC-MH722HM (serv.man6). Part 4 - Mechanical adjustments and assemblies (9-27) - Sharp VCR Service Manual (repair manual)

vc-mh722hm (serv.man6) service manual
Model
VC-MH722HM (serv.man6)
Pages
19
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Service Manual
Brand
Device
VCR / Part 4 - Mechanical adjustments and assemblies (9-27)
File
vc-mh722hm-sm6.pdf
Date

Read Sharp VC-MH722HM (serv.man6) Service Manual online

9
VC-M522HM
VC-MH722HM
VC-MH732HM
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
5.
JiGRH0002
BR
JiGSG2000
BS
JiGSG0300
BF
6.
7.
JiGADP003
BK
2.
Torque Gauge
Tension Gauge
These Jigs are used for checking
and adjusting the reel disk height.
When fixing any part to the threaded
hole using resin with screw, use the
jig. (Specified torque 5 kg)
This cassette torque meter is used for check-
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. Rotary transformer clearance
adjusting jig.
There are two gauges used for the
tension measurements, 300 g and
2.0kg.
4.
Torque Driver
JiGTD1200
CB
9.
JiGDRiVER11055
AR
Reverse guide height
adjusting box driver
This Jig is used for height adjustment of the
reverse guide (for reverse guide height ad-
justment).
Guide roller height
adjustment drive
This screwdriver is used for adjusting the
guide roller height.
For X value adjustment
X value adjustment
gear type screw driver
This Jig is used for height
adjustment of the reverse guide.
13.
JiGRVGH-F18
BU
12.
JiGDRiVER-6
BM
Reverse Guide Height
Adjusting Jig
11.
JiGDRiVERH-4
AP
Video
Audio
Track
625 Monoscope
6kHz
35
µ
m
625 Monoscope
6kHz
and
and
49
µ
m
Colour bar
1kHz
VROUBZFS
10. Alignment Tape
CK
VROCPSV
10
VC-M522HM
VC-MH722HM
VC-MH732HM
MAINTENANCE CHECK ITEMS AND EXECUTION TIME
Perform the maintenance with the regular intervals as follows so as to maintain the quality of machine.
Parts
Maintained 500
hrs.
1000
hrs.
1500
hrs.
2000
hrs.
Remarks
Possible symptom
encountered
Upper and lower drum ass’y
Pinch roller
Capstan D.D. motor
Reel belt
Idler ass’y
Tension band ass’y
Screen swaying
Loading motor
Limiter pulley
Supply/take-up main brake levers
Tape slack
A/C head
Guide roller ass’y
Sup guide shaft
Reverse guide
Slant pole on pole base
Full erase head
Colour and beating
Lateral noises Head
occasionally blocked
Small sound or sound dis-
tortion
Poor S/N ratio, no colour
Poor flatness of the envelope
with alignment tape
Cassette not loaded or un-
loaded
No tape running, tape
slack
Clean tape contact part with
the specified cleaning liquid.
Abnormal rotation or significant vi-
bration requires replacement.
Clean rubber and rubber
contact area with the speci-
fied cleaning liquid.
Clean tape contact area with
the specified cleaning liquid.
No tape running, uneven col-
our
No tape running, tape
slack, no fast forward/re-
wind motion
No tape running, tape
slack
Replace the roller of the
cleaner when it wears down.
Just change the AHC roller
assembly for new one.
AHC(Automatic head cleaner)
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.
11
VC-M522HM
VC-MH722HM
VC-MH732HM
Figure 4-1.
• Reassembly
1. Before installing the cassette housing control, short-
circuit 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 ap-
pears. 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. 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 per-
form cassette loading operation.
TO RUN A TAPE WITHOUT THE CASSETTE
HOUSING CONTROL ASSEMBLY
1. Remove the full-surface panel.
2. Short-circuit TP801.
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.
REMOVING AND INSTALLING THE CASSETTE
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
Weight to prevent
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.
12
VC-M522HM
VC-MH722HM
VC-MH732HM
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 Sup/Tu 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.
4. Assemble the Sup 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 Sup 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 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 15), and check the brake torque (see
page 17).
• 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 4-6.
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.
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.
Tension arm ass'y
Supply reel disk
Take-up reel disk
Master plane
Reverse
guide
Position
pin
Sup main brake ass'y
Tu main brake ass'y
Supply reel disk
Cassette lock
release shaft
Take-up reel disk
Tension band ass'y
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