Dual C 810 Service Manual page 7

Fig. 5 Base plate (printed wiring side)
Mechanical section
General information
The item numbers listed refer to the lists of replacement parts
and exploded diagrams below.
1. Removing the housing plate 1 and the baseplate
Remove the four machine screws 2 and the four washers 3.
Withdraw the housing plate 1 from behind.
In order to remove the baseplate, the four machine screws 44
on the underside of the unit should be loosened and both the
supporting feet 41 and the three sheet metal screws must be
removed.
Removing the fascia 18
Remove the housing plate 1 as described above.
Withdraw the rotary turn switches 31 and 32, the four push
keys 21 and the rotary turn switch 20.
The three countersunk head screws 19 on the upper and
lower fascia should be removed.
The fascia 18 may now be taken off.
a) Removing the cassette retaining plate 117
When repairing the mechanical section, it is advisable to remove
the cassette retaining plate 117 complete with both stop but-
tons 116. To do this, proceed in the proper fashion as follows:
Press the connecting spindle 12 into the bearing spindle 10
and remove it. Pivot the protective head cover 118 upwards.
With the aid of a screwdriver, extract both retaining lugs Lon
the cassette retaining plate 117. Carefully withdraw the cas-
sette retaining plate 117 from the unit and remove the bulb
114 together with its rubber socket.
b) Disengaging the contactor on the cassette retaining plate 123
In order to check the playback or fast wind/rewind function
without inserting a cassette, the contactor F of the cassette
grip 123 must be disengaged as follows:
Operating the playback key or the fast wind/rewind key, the
contactor F must be disengaged from the left cassettegrip 123,
thereby allowing the key to click into position.
Motor
a) Replacement
In order to replace the motor 154, the motor belt and the
flat belt should be firstly removed from the drive pulley
141. Rotate the motor in a counterclockwise direction —
bayonet-type socket — and remove the motor 154. Now
solder off the connection leads from the printed circuit
board.
Loosen the grub screw and remove the drive pulley 141.
Screw off the retaining plate of the motor 154 and fix it
to the new motor.
Place the drive pulley 141 onto the spindle of the new
motor 154. Set the clearance gap between drive pulley
141 and retaining plate at approximately 0.3 mm, then
tighten the grub screw (fig. 7). Solder the connection
leads to the printed circuit board (red = plus). Insert the
motor into the unit and, by rotating it in a clockwise
direction — bayonet-type socket — lock it in position.
Replace the flat belt and motor belt onto the drive pulley
141.
b) Motor speed — tape speed
Test assembly as described below under 6. "Speed accuracy."
The tape speed may be adjusted by means of an insulated
screwdriver on the reverse side of the motor (fig. 7).
The speed is correctly adjusted if the measured result is
between —1 and +0.5 % deviation.
Drive belts
In order to replace defective drive belts — belt arrangement
diagram fig. 8 —, proceed as follows:
The motor belt A may be removed or replaced with no diffi-
culty. Remove the three machine screws 183. Take off the
lower plate 155. The flat belt B and the counter belt C may
now be replaced. Withdraw the flywheel 144 from the
bearing bush.
10
o2me
A
Fig. 7
Fig. 8
Important:
The polyethylene washer 174 on the front side of the unit
will fall out.
The counter belt C 2 and the take-up belt D may now be re-
placed. When the belts have been properly replaced, replace
the polyethylene washer 174 onto the spindle (capstan) of
the flywheel 144. Furthermore, it is advisable to press the
fast forward or rewind key and to clean the capstan and the
drive belt with a cloth soaked in methylated spirit.