Nakamichi BX 300E Service Manual

Page 2

CONTENTS

1.
2.
3.

10.

12.

General ...................................................................... 2
Test Tapes and Gauges ............................................................ 2
Mechanical Adjustment ........................................................... 3
3, 1 Record Head and Playback Head Tilt Adjustment ................................. 3
3. 2 Head Base Stroke Check .................................................. 3
3. 3 Erase Head Stroke Adjustment and Tape Guide Height Check .......................... 3
3. 4 Erase Head Height and Tilt Adjustment ........................................ 4
3. 5 Playback Head and Record Head Height Adjustment and Azimuth Alignment ............... 4
3. 6 Pressure Adjustment of Take-up Pressure Roller ................................... 5
3. 7 Tape Travelling Check .................................................... 5
3. 8 Eject Damper Adjustment ................................................. 5
3. 9. Reel Motor Speed Adjustment in Play Mode ..................................... 5
3 10. Tape Speed Adjustment ................................................... 5
3 11 Lubrication ........................................................... 5
Parts Location for Electrical Adjustment ................................................ 6
Electrical Adjustments ............................................................ 7
5. 1. Adjustment Instructions .................................................. 7
5. 2. Playback Frequency Response .............................................. 9
Mechanism Assy and Parts List ...................................................... 10
6. 1. Synthesis ............................................................ 10
6. 2 Front Panel Assy (A01) .................................................. 11
6. 3 Synthesis Mechanism Assy (A02) ............................................ 11
6. 4 Front Chassis Ass'y (301) ................................................. 12
6. 5 Cover Plate Assy (B02) ................................................... 13
6. 6 Mechanism Ass y (1303) ................................................... 14
6. 7. Rear Panel Assy (304) ................................................... 15
Mounting Diagrams and Parts List .................................................... 15
7. 1. Power Switch P. C. B. Ass y ................................................. 15
7. 2. Shut-off P.C.B. Assy ..................................................... 15
7. 3. Fuse P.C.B. Assy ....................................................... 16
7. 4. Volume P.C.B. Assy ..................................................... 16
7. 5. Input Amp. P.C.B. Assy .................................................. 17
7. 6. Meter Amp. P.C.B. Assy .................................................. 17
7. 7. Dolby NR Switch P.C.B. Assy .............................................. 17
7. 8. Control Switch P.C.B. Assy ................................................ 18
7 . 9. Counter P.C.B. Assy ..................................................... 18
7. 10. Tape Switch P. C. B. Assy .................................................. 18
7. 11. MaianCB Assy ....................................................... 19
Schematic Diagrams ............................................................. 23
B. 1. IC Block Diagrams ...................................................... 23
8. 2. Schematic Diagrams ..................................................... 24
Timing Chart and Eq. Amp. Frequency Response .......................................... 26
9. 1. Timing Chart .......................................................... 26
9. 2. Eq. Amp. Frequency Response .............................................. 26
Wiring Diagram ................................................................ 27
Block Diagrams ................................................................ 28
11. 1. Amplifier Section . . 28

11. 2. Mechanism Control Section ................................................ 29
Specifications ................................................................. 30

Page 5

8.4. Erase Head Heilht and Tilt Adjustment
Refer to Fix. 3.4.

(1)
(2)

(3)
(4)

(5)

Remove the Cassette Cue Asay, Head Mount Base Assy and
Cover Plate Assy.

Load an EH Tilt Check Gauge 5 in the cassette deck.

Set the cassette deck in Stop mode.

Cheek to insure whether one of the 3 Beacons i5 illuminating.
Look down the mirror and slowly turn the Screw Height
counterclockwise (or clockwise) so that the two horizontal
lines on the minor will become superposed on the line (in
different color) of the erase head, and check to inane
whether the first Beacon is illuminatini.

Turn Screw Tilt counterclockwise (or clockwise) to light
on the second Beacon. Excessive turning will cause the first

3.5. Playback Head and Record Head Height Adiustment and

Azimuth Annunent

Refer to Fig. 3.5.

(1)
(3)

(b)
(c)
(d)
(e)
(f)

Playback Head Heiaht Adiustment and Azimuth Albument
Set the Monitor switch to Tape. then connect a VTVM to the
Output Jacks.

Load a 1 kHz Track Alignment Tape, then set the cassette
deck in Play mode.

Turn the PH Height Gear until the outputs of both channels
become minimum.

Load a 15 kHz Azimuth Tape, then set the cassette deck in
Play mode.

Turn the PH Azimuth Alignment Screw until the outputs of
both channels become maximum.

Repeat above steps (b) through (e) one or two times to
obtain oytimum performance.

PHHevgm new
PH Azimmn Ahgnmem

(5)

(7)

(8)

Beacon to light off. Adjustments 0! Screw Tilt" will there-
fore be conducted till both of the first and the second
Beacons illuminate.

Tum Screw Azimuth counterclockwise (or clockwise) to
light on the third Beacon. Excessive turning will cause either
the first or the second Beacon to light oft, and therefore
adjust Screw Azimuth until all of the 3 Beacons illuminate.
Cheek to insure whether the horizontal line on the mirror
correspond: to that on the erase head. If not, (4) through ('7)
will have to be repeated till satisfactory results are obtained.
After completion of adjustment. 3 pcs. of screws shall be
locked with lock tight paint.

Note: Before use of this gauze, check to insure freedom from dust

(2)
(a)
(b)

(C)

(d)
(e)

(E)

svmem

l

F18. 3.5

or dirts. or overflow in the move of the erase head surface.

Record Head Height Adiurtment and Azimuth Alignment
Set the cassette deck in Stop mode.

Set the Monitor switch to Tape. Eq. switch to 70 us and Tape
Selector switch to ZX.

Load a reference ZX tape and connect a VTVM to Output
Jacks.

Feed in 400 Hz (0 dB) to the Input Jacks.

Set the cassette deck in Record and Play mode and tum the
RH Height Gear until we outputs of both channels become
maximum.

Feed in 15 kHz (-20 dB) to the Input Jacks and turn the RH
Azimuth Alignment Screw until the outputs of both channels
become maximum.

Repeat (d) to (f) one or two times to obtain optimum per-
formance.

RH Hugh! Adjustment

RH Ammummugnmem