Akai 4000DS Service Manual page 11

3. TAKE-UP REEL SHAFT ASSEMBLY
ADJUSTMENT (See Fig. 7 at right)
Felt clutch material (2) is attached to the bottom side
of the reel table base plate (1) so that the recording
tape will not stretch during fast forward operation
due to excessive tension. To check the amount of
friction of this part, install a 5-inch reel with a 60 mm
diameter tape, and gently pull the end of tape upward
with a spring scale. Adjust the conical spring (4) so
that the amount of tension at this part is kept
between 400 and 500 grams. Other felt clutch
material (10) is attached to the take-up roller (II).
This is to provide proper slippage during FWD or
REC operation. The procedure for checking friction
of this part is the same as the foregoing, and between
150 and 180 grams of friction provides the best
results. Adjust the spring plate (7) just under the
take-up roller (II). When the unit is set to rewind
operation, the amount of friction of this part will
decrease to from 15 to 20 grams. Check to sec
whether this is satisfactory. If not, adjust the spring
(12) and the pressure of the set sleeve (13).
4. RECORDING/PLAYBACK CHANGING
MECHANISM (See Figs. 8, 9)
Turning The FWD/REC knob (N) to recording posi¬
tion causes Lever (a) to pull. Recording Lever (b) (as
illustrated by dotted line), and the FWD/REC chang¬
ing Switch (SW-9) is turned to recording position. If
Lever (a) docs not pull Lever (b) properly. Changing
Switch SW-9 will not operate properly. This may
cause abnormal oscillation and inability to record. In
this case, loosen Screw (c) and adjust lever.