Harman Kardon CD491 - Page 17

6. Supply pinch roller height adjustment
1) Install the M-300 head gauge plate.
2) Set the unit in the PLAY state. With the adjust-
ment chip applied to the tape guide of the supply
pinch roller, check the tape guide to chip clearance.
Make an adjustment with the adjusting screw D
in the below Fig. 6 so that the upper and lower
clearances become equal.
3) After the adjustment, repeat STOP-PLAY and re-
check the height.
D Fig. 6
7. Erase head flapping confirmation
As in step 5, visually check the erase head flapping. If
the clearance is large, make an adjustment by insert-
ing a spacer or replace the erase head.
8. Azimuth adjustment
When the maximum level point of R channel does not
equal that of L channel, connect the oscilloscope as
shown in Fig. 7 and proceed with azimuth adjust-
ment so that L and R channels are in phase.
a) Connect L channel tape out to “X(or V)” and R
channel to “‘Y (or H)"’. Observe the lissajouss wave-
form.
b) Set L and R channels to monaural. Adjust vertical
and horizontal gain so that the waveform becomes
45 degree.
c) Adjust azimuth so that the measurement of “a”
becomes maximum and the measurement of ‘b’””
becomes minimum against 45 degree line.
output output Fig. 7
9. Tape pass confirmation
1) With the mirror cassette (MC-109C without pad)
in the PLAY state, check the tape for snaking
or curling at the side.
2) Confirm by repeating PLAY-STOP more than
twice. fe
© Contact or curling at the tape quide
Curling must be corrected but contact is accept-
able.
Watch carefully between the tape guide of the
pinch roller and the erase head as flapping tends
to occur there.
© If flapping exists, perform checking as described
in the following 3) and on.
3) When the tape transport is unstable;
a. Re-adjust the supply pinch roller height as in
step 6. Then perform the azimuth adjustment as
in step 10 and check the tape transit. If the tape
transit is satisfactory, check to ensure that the
erase head height is proper.
b. If the pinch roller height adjustment can not
correct the unstable tape transport, check each
part for parallelism.
© Check the capstan spindle for tilt. If it has a
tilt, try tilting the record and playback heads
in the same direction.
® If the tape flapping exists right before the
erase head, eliminate it by tilting the erase
head with a spacer inserted A or B between
the erase head and erase head base as shown
in the Fig. 8.
® Check for parallelism of the tape guide of the
supply pinch roller and the capstan. If they
are not parallel, replace the supply pinch
roller assembly.
@ Check for parallelism of the take-up pinch
roller and the capstan. If they are not parallel,
replace the take-up pinch roller assembly.
Note: Make sure to perform the azimuth
adjustment after each adjustment and
then check the head height and flap-
ping.
Erase head
Erase head base
Fig. 8