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Adjustment playback head K1/K101
(Fig. 12)
a. Adjustment of the head inclination
Adjust the playback head with nut C in such a
way that the front of the head is exactly parallel
with the tape or at right angles to the mounting
plate
Check:
. Place a full-modulated 18 cm test tape with a
frequency .. 10 kHz on the recorder, or use a
full 18 cm tape with on top a test tape 1 kHz-
13 KHz (code number 4822 397 30014)
. Connect an mV-meter to BU4
MONITOR
point 3/2
. Recorder in position "START"
- "A" - "STEREO"
"9.5"
. Note the meter reading
. Slightly brake the full reel with the hand
. Note the meter reading
. Connect the mV-meter to BU4
MONITOR
point 5/2
and repeat the above actions.
When braked, the output signal should not
increase over 2 dB. If both output signals
increase by more than 2 dB, the tape transport
should be checked (see tape adjustments)
If only track 1 should increase by more than
2 dB when braked, the head inclines backward,
if track 3 increases more than 2 dB, the head
inclines forward.
b. Tangential adjustment
Check carefully if the head groove is in the centre
of the contact surface of the tape. {f necessary,
loosen the screws B and move the head.
c. Adjusting the height of the head (Fig. 13)
- Coarse adjustment
. Place a tape on the set
. With nuts C/D and screw A, adjust the height
of the head in such a way that the top of the
upper core lies just under the top of the tape
N.8.: Nuts C and D and screw A should be
turned to exactly the same extent in order
not to change the adjustment of the head
inclination
- Fine adjustment with test tape 1 kHz-13 kHz
. Connect an amplifier to BU4 MONITOR
. Recorder in position "START"
- "A" - "1-4" -
"o.5°
. With nuts C and D, and screw A, adjust the
height of the head such that the 1 kHz signal
is just audible above the noise
d. Azimuth adjustment with test tape 1 kHz-13 kHz
- Connect an mV-meter to BU4 MONITOR
point 5/2
- Recorder in position: "START"
- "A" - "1-4" -
"9.5"
- With screw A, adjust the azimuth of the head in
such a way that the playback of the 13 kHz signal
is maximal. When the playback of the 1 kHz
Signal gets stronger again, the height of the head
should be re-adjusted.
Adjustment recording head K2/K102
a. Head inclination - tangential - height of head - and
azimuth adjustment
- Detach the wiring of the recording head K2/K102
with a soldering iron
- Ditto, that of the playback head K1/K101
to the
recording head K2/K102
- Adjust the head inclination, head slit, height of
the head and azimuth of K2 according to the
procedure for the playback head K1.
- Readjust the wiring after these adjustments
b. Phase difference recording/playback head
For the fine-adjustment of the azimuth of the
recording head K2/K102 according to the phase
adjustment method,
it is absolutely necessary
to perform the aforementioned adjustments,
in
order to prevent phase differences > 90°.
- Feed a signal of 1 kHz to BU3 LINE IN/OUT
points 3/2 and 5/2
- Connect a double beam oscillograph to BU4
MONITOR
(e.g. point 5 of BU4 to Ya input and
point 3 of BU4 to Yb input).
- Recorder in position: "RECORDING"
- "A" -
"STEREO"
- "19"
- With screw A, adjust the recording head in such
a way that the two signals are in phase.
- Check the phase difference likewise on higher
frequencies and, if necessary, correct the
azimuth adjustment with screw A of the
recording head K2/K102.
Remarks:
1. After the mechanical
adiustment of the heads,
the following electrical measurements and
adjustments should be performed
a. Recording/playback sensitivity
b. Premagnetisation current
c. Frequency characteristic
2. After completion of the adjustments, nuts C
and D and screw A shouid be secured with
lacquer.
When replacing the recording head K1/K101
it is
advisable to likewise replace the pressure felt
(see "Mechanical checks and adjustments").
Erase
head K3/K103
Check if the core surface near the core groove is
smooth.
If it has become coarse, it is necessary
to replace the erase head, as otherwise the tape
may be damaged.
A new erase head needs no adjustment. The tape
guides of the erase head are fixed points for the
tape transport. It is therefore advisable to check
the tape transport after replacement of the erase
head.
BRAKES
The recorder is braked both mechanically and
electrically (see "Operation of the control section").
Mechanical
brake (Fig. 14)
- The force to move the drake bracket from rest
position to such an extent that the distances E
are 1.5 mm, should be 65-75 g.
- From this position, a force of 55-65 g is required
to bring the braking magnet back to the rest
position. Adjustments can be made by bending the
bracket with spring D attached.
- In pulled-on position of the braking magnet the
distance E should be 1.3-1.5 mm, to be adjusted
by moving the braking magnet after loosening the
screws C.
- With braking magnet off, the distance B should be
0.3-0.5 mm, to be adjusted by bending tag A.
Electrical brake
No adjustments are necessary for the electrical! brake.
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