Dual C 810 Service Manual page 8

. Speed accuracy
Measure with a Wow meter (e.g. Woelke ME 101 or ME 104
or Franz EMT 420 A) and Wow test cassette 3150.
Setting the test instrument:
0.3 % measurement range, weighted.
Important: In order to avoid incorrect measurement caused
by jamming tape travel, it is recommended to
operate the forward and rewind button with the
test cassette inserted.
Typical measured values (playback) of the Dual cassette deck.
£0.08 —0.12 %
Individual higher deflections should not be weighted
since they are the result of bad tape-head contact
caused be detrition, dust or felt particles.
If necessary, check the following points:
a) Clean pinch rolier and capstan
b) Check pinch rojler for freedom of movement
Fig. 9
155
144
Ci : Ee vie = D
C2
11
c) The take-up torque, which is adjusted at the coupling,
should be 55 1 mN m (55 + 10 pem). Slightly fluctuating
values have no effect on the speed accuracy. At the same
time, the torque on the non-driven side should be 2— 6 pcm.
A higher or varying value suggests that the bearing of the
left winding gear is defective.
d) Replace the flat belt
e) Replace flywheel
7. Pressure lever 0.1 mN m= 1 pem
The pressure lever 128 and the V spring 127 may be removed
after the lock washer 167 has been loosened. Reassembly in-
volves the reverse procedure. However, please ensure that the
V spring 127 is correctly repositioned. With the pause button
disengaged (device switched to play), the pinch roller should
be pressed against the capstan by the V spring 127 with a
force of 400 p t ] QP. lf necessary, this should be alteredby
pretensioning of the V spring 127.
Correct functioning of the pressure lever 128, may also be
checked using the test cassette (Dual item no. 232 797) inthe
following manner.
Insert the test cassettes. Press the play key. Brake the driver
101 on the supply real side slowly until the real comes to astop.
The tape tension should be greater than 10 mN m (100 pcm).
With the "'pause'' button engaged and the start button com-
pletely depressed, the clearance between the capstan and the
pinch roller should be 0.4 — 1 mm. This may be adjusted by
bending the pressure lever.
8. Brake plate
When replacing the rubber sleeves 122 on the brake plate 131,
please bear the following in mind:
During fast forward/rewind, there must be a clearance on the
non-driven side of 0.1 — 0.2 mm between the rubber sieeve
and the brake drum of the driver 101. if necessary, bend the
lugs on the brake plate 131 (fig. 10).
9. a) Coupling
To ensure satisfactory winding, the winding torque of the
coupling must be correct. The tape tension during winding
should be 5.5 + 1mN m (55 + pcm). Thisshould be measured
using a test cassette (Dual part number 232 797). Readjust-
ment of the entire device may be carried out as follows:
1) Isolate the unit from the mains!
2) Press the fast rewind key (<<).
3) Rotate the left driver 101 until 1 of the 2 adjustment holes
becomes visible through the aperture B in the cassette
retaining plate (fig. 10). Then, using the special adjustment
key E (Dua! part number 203 933), adjust the take-up
torque. Rotation in a clockwise direction increases the
take-up torque. Rotation in a counter clockwise direction
reduces the take-up torque.
b) Coupling pully torque
In order to ensure uniform torque during fast wind/rewind,
the upper section of the coupling pulley 136 is separated from
the lower drive diameter of the take-up belt by a friction
coupling (fig. 11).
Checking:
Insert the special torque test cassette {Dual part number 238 600).
Press the fast forward/rewind key. Over a series of measurements,
open and close the cassette grip 123 so that the pointer returns
to "0" on both scales. The torque should measure 8 — 13 mNm
(80 — 130 pcm). Typical values for new drive pulleys are 9 — 14 mN
m (90 —~ 140 pcm). If necessary, hold the coupling pulley 136 in
a fixed position. Adjust the friction coupling as necessary with
the aid of a spanner or flat-nosed pliers.
Important: The main belt A must not display any signs of slip or
dirt contamination!