DOWNLOAD Sharp DV-NC70H (serv.man9) Service Manual ↓ Size: 14.28 MB | Pages: 113 in PDF or view online for FREE

Connector for
Capstan Motor 

Connector for
AC Head 

Connector for R/T

AE Connector

End Sensor

REC Tip SW

This positioning hole 
should be at frontside.

Master Cam Position

MODE SW

Start Sensor

This pin should be 
at frontside.

180

°

270

°

0

°

90

°

MODE SW Position

2. Mechanical initial setting
• When performing the initial setting manually, press and

turn the flange of the worm as shown in the figure below.

• When applying constant voltage to the loading motor

• Unsolder at least one of the loading motor wires.
  If voltage is applied with the wires connected, the IC of

the capstan motor may be damaged.

• The voltage applied to the motor must be maximum of

9V.

  If the mechanism is activated by applying excessive

voltage to the motor and is locked in the starting or end
position, it may be damaged.

PARTS WHICH NEED PARTICULAR CARE
When installing the mechanism chassis on the Main PWB
unit, take care so as to prevent deformation due to contact
of mechanism chassis with REC Tip SW.

Rotate the flange of worm gear by using thin stick.
CW ---- Loading direction
CCW -- Ejection direction

Note
Be careful not to damage the gear of worm gear
and worm wheel gear. It might cause a strange sound.

• After confirming that the mechanism is returned to the

initial setting position, mount the cassette housing to the
specified position. (This method is applied to the
mechanism only.)

• After pushing the tip of the drive lever in the position shown

in the figure, push the cassette housing backward to
mount it to the specified position.

INSTALLING THE MECHANISM ON MAIN PWB
Lower the mechanism vertically with attention to its edges,
and mount it without damaging the parts. Engage the pin of
the mode SW and the long hole of the master cam.
* Please make sure to insert correctly.

If not, strange moving will occur and will couse mecha-

nism damage.

•   Reassembly
1. Before installing the cassette housing control, short-

circuit between TP803 and TP802 on VCR Operaton
PWB, press the eject button. The master cam turns and
stop in eject position. Fit the drive lever to master cam
through main chassis, push down and slide the drive
lever towards to master cam.
Push the cassette housing backward to mount it to the
specified position.

•   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) Slightly lift the rear of the cassette housing and slide

it toward you. Slide the drive lever by pushing it toward
you, and disengage the tip of the drive lever from the
hole of the chassis. Then, pull up the cassette control
housing .

1

Main shaft

Cassette 
housing

From Bottom View

Pinch Drive
Cam

Synchro
Gear

Master 
cam

From top view

Main chassis

Drive 
Lever

Phase 
matching

Master cam

Line of 
synchro 
gear.

Hole of Pinch 
drive cam.

*1

*2

*1: The hole of the pinch drive cam must be directed

toward the synchro gear shaft.

*2: The long hole of the master cam must be located on

the front side.

2. Install with the reverse order of removal. After installation

is completed, disconnect and connect the AC plug.

Notes
1. In the case when you use the magnet screw driver, never

approach the magnet driver to the A/C head, FE head,
and drum.

2. When installing or removing, take care so that the

cassette housing control and tool do not contact the
guide pin or drum.

3. After installing the cassette housing control once per-

form cassette loading operation.

1. Remove the full-surface panel.
2. Short-circuit between TP803 and TP802 on VCR

Operation PWB.

3. Plug in the power cord.
4. Turn off  the power switch.
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 to prevent

floating.

9. Turn on the power switch.
10. Perform running test.

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.

500g

Weight to prevent
float (500g)

Mechanism chassis

• 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.

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.

Notes:
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 8-12), and check the brake torque (see 8-
16 ).

Take-up reel disk

Supply reel disk

Ten

Tension arm ass'y

Supply main brake

Tension band 
ass'y

Take-up main brake ass'y

• Removal
1. Remove the cassette control housing assembly.
2. Remove the Supply/Take-up main brake ass'y.
3. Lift the tension band on the reel disk side, remove tension

band from the tension arm ass'y.
(Do not deform it excessively.)

4. Remove the reel disk.

Note:
Take care so that the tension band ass'y and main brake
ass'y are not deformed.

Note:
1. 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.

2. Whenever replacing the reel disk, perform the height

checking and adjustment.

• Height checking and adjustment
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.

Supply reel disk

Take-up reel disk

Cassette lock
release shaft

Master plane

A

B

Master plane

Reel disk height
adjusting jig

Mechanism chassis

Reel disk

10 

± 0.2mm

Reel disk

• 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.

2. Make sure that the indication of torque gauge is not less

than 25mN·m (255gf·cm).

Torque gauge

25mN·m (255gf·cm)
or more

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

Idler ass'y

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

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

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

belt.

Notes:
1. Hold the torque gauge by hand so that it is not moved.
2. Do not keep the reel disk in lock state. Do not allow long-

time measurement.

CW

• 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 25mN·m (255gf·cm).

Torque gauge

25mN·m (255gf·cm)
or more

Supply reel disk

Idler ass'y

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

• Adjustment
1. If the rewind winding-up torque is less than the specified

value, clean the capstan D.D. motor pulley, reel 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

reel belt.

Notes:
1. Hold the torque gauge by hand so that it is not moved.
2. Do not keep the reel disk in lock state. Do not allow long-

time measurement.

CCW