Akai 4000DS Mk-II Service Manual

1. PINCH WHEEL ADJUSTMENT
It is important that the pinch wheel shaft be kept in
perfect alignment with the capstan shaft. Proper
pinch wheel pressure is between 1,000 and 1,150
grams when the unit is operated at the tape speed of
7'A ips. Any deviation from this specification will
result in wow and flutter. Check pinch wheel pressure
with a spring scale, and if necessary, adjust the pinch
wheel load spring.
Pig- 8 Fig. 9
2. SUPPLY REEL SHAFT ASSEMBLY
ADJUSTMENT (See Fig. 7 at left)
Felt clutch material (2) is used between the lower
side of the reel table base plate (I) and the rewind
pulley (3) to protect recording tape from excessive
tension during rewind operation. 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 the tape upward with a spring scale. Adjust the
conical spring (4) so that the amount of tension is
kept between 400 and 500 grams. Other felt clutch
material (5) is attached to the supply roller (6) to
provide proper slippage during FWD and RFC oper¬
ation. The procedure for checking friction of this part
is the same as the foregoing, and between 80 and 100
grams of tension gives best result. Adjust the spring
(7) just under the supply roller (6). When the unit is
set to fast forward operation, the amount of friction
will decrease to from 15 to 20 grams. Check to see
whether this is satisfactory. If not, adjust the spring
plate (8) and the pressure of the pulley. (9).

Akai 4000DS Mk-II Specifications

General

Type	Reel to Reel
Track System	4-track, 2-channel, stereo/monaural system
Signal to Noise Ratio	50dB
Reel Size	Up to 7 inch reel
Total Harmonic Distortion	1.5%
Output	0.775V (line)
Tape Speed	3.75 & 7.5 ips
Heads	1 x erase
Input Sensitivity	50mV (line)
Semiconductors	6 x Transistors
Inputs	Line
Outputs	Line