Dual C 822 Serviceanleitung Seite 22

Mechanical section
General notes
Ih
o1
The item numbers stated refer to the lists of replacement parts and ex-
ploded diagrams below.
1. Removing the housing and the base plate
Remove the four machine screws 2 and the four washers 3. Withdraw
the housing 1 from the rear.
In order to remove the base plate, the six machine screws 53 on the
lower section of the unit must be loosened.
2. Removing the front trimplate
Remove the housing 1 as described above.
The six head screws 19, three on the front trimplate upper section
and three on the lower section must be removed. The front trimplate
6 can now be removed.
3. Removing the cover
When carrying out repairs on the mechanical section, we recommend
that the cover 108 remowed. The most practical method of removing
the above parts is to proceed as follows:
Loosen mounting srews of holder 110 . Remove holder 110 together
with head dust cover 112. Disconnect cable connectors of leads to
the LED plate 105 and photo electric cell plate 118 and open wiring
harness. Unlock mounting tab L of cover 108. Remove cover 108
carefully.
4. Motor
a) Replacing the motor
In order to replace the motor 172, the motor belt and the flat belt
must f irstly be removed from the drive pulley 173. Loosen mounting
screws of holder 110. Remove holder 110 with head dust cover
112 and unlock mounting tab L of cover 108 (do not remove).
Unlock motor bracket 155. Remove the three mounting screws
of mounting set 147. Remove the motor 172.
Unsolder the connection leads from the printed circuit board.
Loosen the grub screw and remove the drive pulley
173
Place the
drive pulley 173 onto the spindle of the new motor 172. Set a
clearance of approximately 1 mm between the drive pulley 173
and the motor retaining plate and then tighten the grub screw.
Solder on the connection leads to the printed circuit board
(red = +I.
Insert the motor into the unit and lock in with the fixing screws.
Fit the flat belt and motor belt to the drive pulley 173.
b) Motor speed - tape speed
Measurement procedure is the same as that described in section
6. "WOW and flutter". The tape speed may be set with the aid
of an insulated screwdriver at the rear of the motor .
The speed is correctly adjusted when a maximum deviation of
- 1 to + 0.5 % is measured.
5. Drive belts
In order to change defective drive belts,you should proceed as follows
(refer to belt diagram):
The motor belt A and the counter belt B can be removed or replaced
without further difficulty. Remove the flat belt C an the drive pulley.
Loosen mounting screws of holder 110. Remove holder 110 together
with head dust cover 112 and unlock mounting tab L of cover 108
(do not remove). Unlock motor bracket 155.
The flat belt C may now be replaced. Draw out the flywheel 164 from
the bearing bush.
Attention! The plastic washer 166 at the front side od the unit will
drop off.
The tape-up belt 0 may now be replaced. Once the belts have been
fitted, the polyethylene washer 166 must be f itted on the spindle
(capstan) of the flywheel 164. Furthermore, it is advisable to press
the fast forward or reverse wind key and clean the capstan and the
drive belt with a cloth soaked in methylated spirit.
6. VVOVV and flutter
Measure with a WOW meter (e.g. Woelke ME 101, ME 104 or Franc
EMT 420 A) and WOW test cassette 3150.
Setting of the test instrument: 0.3 % measurement range, weighted.
In order to avoid incorrect measurement caused by jamming tape
travel we recommend that the test cassette be rapidly wound and
revvound occasionally.
Typical values for the Dual cassette deck (playback)
±0.08 - 0.12%
I ndividual higher deflections should not be weighted as they are the
results of band-tape-head contact caused by detrition,dust or fett par-
ticles.
If necessary, check the following points:
a) Clean the pinch roller and capstan
b) Check the pinch roller for free movement
c) The take-up torque, which is adusted at the coupling, should be
5.5 ± 1 mN m (55 ± 10 pcm). Slightly fluctuating values do not
affect the WOW. At the same time, the torque on the non-driven
side should be 0.2 - 0.4 mN m(2 -4 pcm). A higher or carying
value suggests that the bearing on the left winding gear isdefective.
d) Replace the flat belt or the flywheel
7. Solenoids
When mounting the tvvo solenoids 143 it is recommended. To
proceed as follows:
Bring the mechanical gear in the upside down position. With, the
solenoids in the operating position move arm 130 to its lower stop
and mount the solenoids.
Adjustment point
When the right winding gear 162 engages the coupling 158 make
sure for minimum play for theet. To compensate unsufficient play
of gear slightly remove the right solenoid backwards. To compen-
sate excessive play of gear slightly remove the left pulling back-
wards.
8. Coupling
To ensure satisfactory winding, the take-up torque of the coupling
must be correct. The take-up torque should be 5.5 ± 1 mN m
(55 ± 10 pcm) when measured with a test cassette (Dual item no.
232 797). Readjustment of the antire unit may be carried out as follows:
1) Isolate the unit from the mains by removing the power cable.
2) Remove the housing 1
3) Rotate the flywheel 164 until one of the two adjustment holes
becomes visible through the hole B in the cover 108. Then, using
the special adjustment spanner E (Dual item on. 230 933) adjust
the take-up torque. Rotating in a clockwise direction will increase
the take-up torque whereas rotating in a counterclockwise direc-
tion will decrease it.
9. Record/playback head, erase head
When replacing the record/playback head 121 you must take the
following preliminary adjustment measures:
Fix the record/playback head 121 together with the flat spring on
the head assembly and then secure it with the bushes and machine
screws Z in such a way that the tape guides B are in line with the tape
guides on the head mounting assembly B 1 and the erase head B 2.
The section entilted "electrical alignment" describes:the procedure
for fine adjustment.
10. Cleaning/lubrication
Always clean the unit when servicing or repairing it.
In order for the unit to function properly, the record/playback head
121, the erase head 120, the pinch roller 136 and the capstan should
always be perfect ly clean. These parts are best cleaned using a cotton
cloth or soaked in methylated spirit. On no account should you
use meta .I objects to clean the unit. Furthermore, the surface of the
magnetic head should never be touched with bare f ingers.
All bearing and sliding points on the unit are adequately lubricated
at the factory. Relabrication is normally not necessary for several
years, since most important parts are provided with oil retainers.
The motor bearings are provided with long-life oil retainers and ther-
efore requiere na lubrication.
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