Nakamichi BX-100 User manual

Nakamichi
Service
Manual
Nakamichi
BX-100
BX-100E
2 Head Cassette Deck

CONTENTS
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Ze. “Ly Tape Guide Height Check for Record/Playback Head and Erase Head .............02 0.000%
2: 2. Head‘ Base Stroke Check: .0..-24-5-0 ashes Nw wee RE Se ee EA PR ee
2. 3. Record/Playback Azimuth Alignment and Height Check ....... 0... cece eee eect eeene
2. 4. Pressure Adjustment of Pressure Roller... 0... 0. cc ee ee ee te eee
2. 5. Tape. Travellirig:‘CReeh. 5.6 e.0 is sce Soe 8 ra eae So eee Meee Sas Sue aeh HE We) eG OIG A ee ie anes
2. 6. Eject Damper.Adjustment: <0. 0c eesiscee ie se oe a eee oboe Ue Bie HE ert Sa he hee ee ee
2. 7: Reel Motor Speed Adjustment in Play Mode ........ 0... cc cece eee ee te eee ee ene nae
2. 8. Tape’ Speed Adjustment: éiiiic 5 alla ics BSG) alg ee We we EE Rie Bede Wee B Soe eS ee ea ee ees
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4, Electrical Adjustments and Measurements ........... 52. - cece eee eee ee ee eee ee eee ee een eens
4. 1. Adjustment and Measurement Instructions ...... 20... 0. cece eee ee eee eee ee ee eee
4, 2. Playback Frequency Response Adjustment ........ 0.0: ce eee ee eee ee eee eet ene
4. 3. Dolby NR Circuit Check 0.0... cc ct ce re ee nw ee eee ence ene n eens
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6. Mounting Diagrams and Parts List ........ 0... cc cece eee ee ee ee eee eee ee eee een eee ene ee
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6. 5. Volume: P.C.B.. Ass? yi 2.5.38.6 Bee Seen Eo Acdo wR case ae ede Seen e evened Roe ees ane SOM, Bee alee ed
6. 6. Dolby NR:P.C:.B: Ass’¥) eis goer eek eas dhe aces te eee Bae le le eae aes Rake eee ete GIG eel
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6. 8. Indicator-P:C.B. ASS’Y cc bees ae ew EN hw Se ee He es Eta i Se ee ae oP alee SMe ee
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10. Timing Chart and Eq. Amp. Frequency Response ....... 0.0... cee eee eee ee eee te eee eee
11, Specifications .............06-- Sig et GN a tas Sie Aa dk Rey Sao WAG Ma, See LaES Se ee eRe Taro eee lo MACE: Genres tak td Sass
1. GENERAL
1.1, Voltage Selector
Voltage selector is installed on the rear panel for Other version of the Nakamichi BX-100.
This voltage selector can select either 120 V or 220-240 V at customer’s disposal.
1.2, Packing Materials and Owner’s Manual
Part No, Description Q
OFO3736A Carton Box BX-100 (Silver)
OFO3750A Carton Box BX-100E (Silver)
OF03737A Carton Box BX-100 (Black)
OF0O3751A Carton Box BX-100E (Black)
OF03674B Packing
0D04311A Owner’s Manual (BX-100.(U.S.A., Canada & Australia) & BX-100E (UK))
0D04317A Owner’s Manual (BX-100 (Others) & BX-100E (220V Class 2))
¢
<
BRN HH ee
1.3. Serial Number
The BX-100 has two versions, Silver and Black.
In the service manual, serial numbers of these versions are identified as follows:
Silver version: A318xxxxx
Black version: A319xxxxx
However, the actual serial number on the serial number plate of the BX-100 is indicated as A318.9xxxxx.
The serial number begins with A318.901001.

2. MECHANICAL ADJUSTMENTS
2.1. Tape Guide Height Check for Record/Playback Head and
Erase Head
With use of an M-300 produced by Information Terminals, tape
guide height check for the Record/Playback and Erase Heads shall
be made, wherein a small block shall be pushed straight down to
the base while in use of the M-300, Refer to Fig. 2.1.
(1) Record/Playback Head Tape Guide Height
(a) Load the base of the M-300 carefully, then set the cassette
deck in Play mode.
(b) Place the small block of the M-300 on the base.
(c) Slide the small block against the tape guide of the Record/
Playback Head, and check to insure that the block is ac-
cepted by the tape guide.
(d) If not, loosen the screw and insert a shim (either 30 um
(0C80048A), 60 um (0C80038A), or 100 um (0C80039A))
to raise the Record/Playback Head, then tighten and apply a
quantity of lock tight paint to the screw.
(2) Erase Head Tape Guide Height
(a) Load the base of the M-300 carefully, then set the cassette
deck in Play mode.
(b) Place the small block of the M-300 on the base.
(c) Slide the small block against the tape guide of the Erase
Head, and check whether the block is accepted by the tape
guide,
2.2, Head Base Stroke Check
Refer to Fig. 2.2.
(1) Load the base of the M-300 carefully, then push the base
toward the Record/Playback Head to eliminate the clearance
between the reference pin and the base.
(2) Setthe cassette deck in Play mode,
(3) Place the small block of the M-300 on the base,
(4) Contact the small block with the Record/Playback Head sur
face and the Erase Head surface, and check whether the end
of the small block is located within the specified tolerance
as shown in the figure.
2.3. Record/Playback Azimuth- Alignment and Height Check
Refer to Fig. 2.1.
(1) Connect a VTVM to the Output Jacks.
(2) Load a 15 kHz Azimuth Tape (DA09004B), then set the
cassette deck in Play mode.
(3)
Tum
the
Azimuth
Alignment
Screw
until
the
outputs
of
both
channels
become
maximum.
(4) Load a1 kHz Track Alignment Tape (DA09007B), then set
the cassette deck in Play mode.
(5) Check to insure that the readings of both channels on the
VTVM are below —25 dB.
If not, replacement of the Record/Playback Head will be
required,
(6) Apply a quantity of lock tight paint to the Azimuth Align-
ment Screw,
2.4, Pressure Adjustment of Pressure Roller
Refer to Fig. 2.3.
(1) In Play mode, measure the torque of the Pressure Roller and
check whether the torque is in a range of 320 +50 g-cm.
(2)
If
torque
is
out
of
the
range,
correct
it
by
changing
the
instal-
lation
point
of
the
Pressure
Roller
Spring.
2.5. Tape Travelling Check
Load the Tape Travelling Cassette (DA09027B), then set the
cassette deck in Play mode and check the following:
(1)
After
more
than
2
seconds,
the
fluctuation
of
the
tape
trav-
elling
on
the
Record/Playback
Head
is
small.
(2) Tape is in contact with the head sufficiently.
(3)
Tape
waving
is
smali
on
the
heads
and
pressure
roller.
2.6. Eject Damper Adjustment
Refer to Fig. 2.4. Load a cassette tape, and with opening the
Cassette
Case
by
pressing
the
Eject
button
and
closing
it
by
hand,
adjust the speed of damper movement by the Adjustment Screw.
cCW: Damper moves fast.
CW: Damper moves slowly.
Fig. 2.3
Decrease
Increase
Damper Adjustment
Screw

2.7. Reel Motor Speed Adjustment in Play Mode
(1) To warm-up the cassette deck, load a C-60 cassette tape and
set the cassette deck in Play mode,
(2) After more than four minutes, load a torque meter TW-211
(made by Sony) and set the cassette deck in Play mode.
(3)
Adjust
VR601
on
the
Main
P.C.B.
Ass’y
to
obtain
exactly
50
g-cm
on
the
torque
meter.
2.8. Tape Speed Adjustment
Refer to Fig. 2.5.
(1) Connect a frequency counter to the Output Jacks.
(2) Load a 3 kHz Speed and Wow/Flutter Tape (DA09006C) and
play it back.
(3)
Adjust
the
Tape
Speed
Adjustment
Volume
incorporated
in
the
Capstan
Motor
to
obtain
3,000
Hz
on
the
frequency
counter,
CCW: Motor drives slowly.
Cw: Motor drives fast.
2.9. Lubrication
The tape transport is of a lubrication-free type mechanism. When
the following parts are replaced, apply the specified lubricant.
(1) Molykote (R) Grease (X5-6020)
Cam Motor Pulley
Thrust portion on the Capstan Shaft
(2) FLOIL GB-TS-1
Washer between Reel Hub Ass’y and Back Tension Spring
(3) Diamond Oil (EP56)
Reel Hub Shaft
(4) Anderol 456
Capstan Shaft
Note: We suggest that you use the above specified lubricant or
equivalent type.
The company dealing in the above lubricant is as follows:
(a) Molykote (R) Grease (X5-6020)
Dowcorning Co., Ltd., 1-15-1 Nishishinbashi, Minato-
ku, Tokyo, Japan
(b) FLOIL GB-TS-1
Kanto Chemicals Co., Ltd., 2-7 Kanda Sakuma-cho,
Chiy oda-ku, Tokyo, Japan
(c) Diamond Oil (EP-56)
Mitsubishi Of] Co., Ltd., 1-2-4 Toranomon, Minato-ku,
Tokyo, Japan
(d) Anderol 456
Toyo Kokusai Oil Co., Ltd,, 3-3-5 Hatchobori, Chuo-
ku, Tokyo, Japan
Decrease
NH
Increase
Copstan Motor
Fig. 2.5

3.
PARTS
LOCATION
FOR
ELECTRICAL
ADJUSTMENT
MPX Filter
L104
L204
TP101
Playbock
Level
©
VREOI
Reel Motor Speed
(Play) vR108 GL VRIO1 vR201
ia Level
vR208 @t
Bios Trap 1P102@
Rec.Cal (Record)
al
1P202©
Bit)
a
om
rrmro(@) orezo3
Peaking
1304
@ Bios Osc. Frequency
© |
Bias Cut
©
VRIOS VRIO6 yRI07
(2) ios
To
VR205 VR206 VR207
Tape Switch P.C.B.
Fig. 3

4. ELECTRICAL ADJUSTMENTS AND MEASUREMENTS
Note:
Electrical
adjustment
should
be
performed
after
mechanical
adjustment
is
completed.
4.1.
Adjustment
and
Measurement
Instructions
Tape Speed
Adjustment
Meter Level
Calibration
MPX Filter
Adjustment
Playback
Level
Calibration
Playback
Frequency
Response
Adjustment
Oscillation
Frequency
Adjustment
SIGNAL OUTPUT
SOURCE CONNECTION
3 kHz Speed
and
Wow/Fliutter
Tape
(DA09006C)
400 Hz to
Input Jacks
400 Hz and
19 kHz +100
Hz to
Input Jacks
Azimuth Tape
(DA09004B)
400 Hz Level
Tape
(DA09005B)
400 Hz Level
Tape
(DA09005B)
10 kHz PB
Frequency
Response Tape
(DA0900 3B)
15 kHz PB
Frequency
Response Tape
(DA09002B)
20 kHz PB
Frequency
Response Tape
(DA09001B)
(—20 dB) to
Frequency
Counter to
Output Jacks
VTVM to
TP101, TP201
on Main P.C.B.
VTVM to
Output Jacks
VTVM to
Output Jacks
VTVM to
TP101, TP201
on Main P.C.B.
VTVM to
Output Jacks
Frequency
Counter to
VTVM across
the additional
0.1 2 resistor
VTVM to
TP102, TP202
on Main P.C.B.
VTVM to
TP103, TP203
on Main P.C.B.
Playback
Eq. SW — 70 us
Record, Pause
Record, Pause
Playback
Eq. SW— 70 us
Dolby NR SW — OFF
Same as above
Record, Pause
Tape SW — ZX
Eq. SW — 70 us
Dolby NR SW — OFF
Same as above
ADJUST-
MENT
Tape Speed
Adjustment
Volume
Main P.C.B.
VR108,VR208
Main P.C.B.
L104,L204
Record/Playback
Head Azimuth
Alignment
Screw
Main P.C.B.
VR101,VR201
Main P.C.B.
R110,R210
R195.R295
R318,R350
Main P.C.B.
L102,L202
Main P.C.B.
L103,L203
REMARKS
Adjust the volume incorporated in the capstan
motor to obtain 3 kHz +0.5% on the frequency
counter.
1. Feed in 400 Hz, then adjust the Input Level
control to obtain 90 mV —0.8 dB on the
VTVM.
. Adjust VR108 (VR208) so that the 0 dB
segment of the level meter starts illuminat-
ing.
. Adjust the Input Level control to obtain
90 mV on the VTVM, then decrease the
generator output level by 20 dB.
. Check to insure that the segment for —-20
dB illuminates,
. Feed in 400 Hz and adjust the Input Level
control to obtain 0 dB (500 mV) on the
VTVM.
. Feed in 19 kHz, then adjust L104 (L204) to
obtain minimum reading on the VTVM
(minimum reading will be less than --30
dB).
Adjust the Record/Playback Head Azimuth
Alignment Screw to obtain maximum readings
of both channels on the VTVM.
Adjust VR101 (VR201) to obtain 90 mV on
the VTVM.
1. Load a 400 Hz level tape and play it back.
2. Load 10 kHz, 15 kHz and 20 kHz PB fre-
quency response tapes and adjust the record/
playback head azimuth to obtain maximum
levels on the VT VM with each tape.
. Read the maximum levels with each tape
and check to insure that the levels against
the 400 Hz level tape are within the follow-
ing ranges.
If not, short R110 (R210) or R195 (R295)
to obtain satisfactory results,
10 kHz (—20 dB) —2 dB to +2 dB
15 kHz (—20 dB) 2 dB to +3 dB
20 kHz (—20 dB) —2 dB to +4 dB
Refer to the “Playback Frequency Response
Adjustment” in item 4.2 for the detailed
description.
. Conduct step 4 ‘“‘Record/Playback Head
Azimuth Alignment”.
. Adjust T301 to obtain 105 kHz on the fre-
quency counter,
. Connect an additional 0.1 2 resistor in
series to the Erase Head, then connect a
VTVM across it.
. Check the erase current by the VTVM.
Erase current will be in a range of 145 mA
to 185 mA (typically approx. 165 mA).
If erase current is not sufficient, increase
it by shorting R318 or R350.
. After completion of the erase current ad-
justment, re-check the bias oscillation fre-
quency,
. Remove the additional 0.1 2 resistor.
. Short both Bias Stop test pins with a clip
to stop the bias oscillation.
. Adjust L102 (L202) to obtain peak read-
ing at 21 kHz on the VTVM.
. Remove the clip from the test pins,
Adjust L103 (L203) to obtain maximum read-
ing on the VTVM.

SIGNAL OUTPUT ADJUST-
Ee SOURCE CONNECTION | move | MENT REMARKS
Adjustment should be made in the order of ZX,
SX and EX,
. Set the Dolby NR switch to OFF,
. Connect a VTVM to output Jacks,
. Set the BX-100 in Record/Pause mode.
. Feed in 400 Hz, then adjust the Input Level
control to obtain 500 mV (0 dB) on the
VTVM.
. Load a reference ZX tape (DA09037A),
reference SX tape (DA09025A) and refer-
ence EXII tape (DAO9066A).
. Adjust Record Cal. VR102 (VR202) for
ZX, VR103 (VR203) for SX and VR104
(VR204) for EXII to center positions,
. Connect the VTVM to TP102 (TP202) on
the Main P.C.B. Ass’y. Adjust Bias VR105
(VR205) for ZX, VR106 (VR206) for SX
Main P.C.B. and VR107 (VR207) for EXII to obtain the
(Level) following bias current in Record/Pause
ZX: mode (the VTVM is connected across a 10-
VR102,VR202 ohm resistor).
SX: ZX: approx. 1 mA
VTVM to Record and Playback | Vp103.VR203 SX: approx, 0.5 mA
TP102, TP202 EX: EXII: approx. 0.3 mA
on Main P.C.B. z VR104.VR204 . Connect the VTVM to the Output Jacks,
and ‘ . Feed in 400 Hz (—20 dB) and 17 kHz (—20
VTVM
and
(Bias)
aB),
then
record,
rewind
and
play
them
Distortion Meter | Dolby NR SW —OFF/| 7y, back.
to Output Jacks ON | VR105,VR205 Adjust Bias VR105 (VR205) for ZX,
SX: VR106 (VR206) for SX and VR107
VR106,VR206 (VR207) tor EXII to obtain the same play-
EX: hae devel at cael ae ae aB) and 17 kHz
(— B) on the VT %
VEIOLYR20e . Feed in 400 Hz (0 dB), then record, rewind
and play it back.
Adjust Record Cal. VR102 (VR202) for
ZX, VR103 (VR203) for SX and VR104
(VR204) for EXII to obtain 0 dB on the
VTVM.
. Repeat above 9 and 10 two or three times
to obtain optimum performance.
. Set the Dolby NR switch to ON.
. Feed in 400 Hz (—20 dB), 10 kHz (—20 dB)
and 17 kHz (—20 dB), then record, rewind
and play them back.
Check to insure that the playback levels are
within +2 dB against the levels in Dolby NR
OFF.
Check to insure whether the total harmonic
distortion is less than 1.0% for ZX and EXII
tapes and 1.2% for SX tape.
. If above is not sufficient, repeat 9 to 14 till
satisfactory results are obtained.
. Set the BX-100 in Record/Pause mode.
. Feed in 400 Hz, then set the Input Level
control to obtain 0 dB (500 mV) on the
VTVM.
. Decrease the generator output control by 20
dB.
i — an
400 Hz (0 dB) Record and Playback ’ Read awed sad uae ita Coad Anes
Overall and 20 Hz to Tape SW — ZX/SX/EX ; check to insure whether the output levels
Frequency 17 kHz VTVM to Eq. SW — 70 us Main P.C.B. are within —20 dB +4 dB.
Response (20 dB) to Output Jacks (ZX/SX) L102,L202 . If above is not sufficient, adjust L102
Adjustment | Tout Jacks 120 us (EX) (L202) to obtain approx. —20 dB on the
Dolby NR SW — OFF VTVM, then conduct step 10 “Record Level
Calibration and Recording Bias Current
Adjustment”’,
. If above is not sufficient, precise re-adjust-
ment of step 6 ‘‘Playback Frequency Re-
sponse’, replacement of Record/Playback
Head or check on item 2.5 “Tape Travelling
Check”? will be required.
. ered the tape with bulk eraser. "
. Adjust the Input Level control to obtain
1kHz
Band
Pass
|
Record
and
Day
back
0
dB
on
the
VTVM,
and
record
the
signals
Filter and VTVM Eq. SW — 70 us on the reference ZX tape (DAO9037A).
to
Output
Jacks
Doiby
NR
SW
—
OFF
.
Turn
the
cassette
tape
the
other
way
round
and
play
it
back.
. Measure the difference between 2 and 3.
. Erase the tape with bulk eraser.
Channel . Adjust the Input Level control to obtain
Separation |1kHz to O dB on the VTVM, and set the Balance
Measure- Input Jacks control to the extreme left (right).
ment
:
.
Record,
rewind
and
play
it
back,
then
mea-
sure the
R ch
(L
ch) level.
1 kHz to
Input Jacks
Same as above Same as above

SIGNAL
OUTPUT
ADJUST-
Erase the tape with bulk eraser,
2 Adjust the Input Level control to obtain
O dB on the VTVM, and record the signals
on the reference ZX tape (DA09037A).
3. Rewind the tape, set the Input Level control
to minimum, and then record again.
4. Rewind the tape, play it back, and then
measure the difference between 2 and 3.
Set the Dolby NR switch to ON,
Feed in 400 Hz, then record, rewind and
play it back.
Adjust the Input Level control to obtain 3%
Record and Playback
Tape SW — ZX
Eq. SW — 70 us
Dolby NR SW — OFF
100 Hz Band
Pass Filter and
VTVM to
Output Jacks
100 Hz to
Input Jacks
IHF-A
Curve,
Record
and
Playback
sop eo NP
Filter,
VTVM
total
harmonic
distortion
in
Playback
mode.
tapout
gaa
and
Distortion
aed
lire
Set
the
Input
Level
contro!
to
minimum
Meter
to
:
then
record
again.
Output
Jacks
Dolby
NR
SW
—
ON
.
After
rewound,
play
back
and
check
the
output level difference between 3 and 4.
Note: The filter of IHF-A curve shall be used in
the measurements,
Adjust the Input Level control to obtain
0 dB on the VTVM.
2. Record, rewind and play it back.
3. Read the distortion meter and check to
Record and Playback
Tape SW — ZX/SX/EX
Eq. SW — 70 us
VTVM and
400 Hz to
Distortion
Meter
; ;
Fi
h
Input
Jacks
(ZX/SX)
insure
that
the
distortion
is
as
follows:
to
Output
Jacks
120
us
(EX)
EXI].....
1.0%
or
less
Dolby
NR
SW
—
OFF
SX
gow
hee
1.2%
or
less
yn
1.0%
or
less
3 kHz Speed
and Wow/
Flutter Tape
(DA09006C)
Wow/Flutter
Meter to
Output Jacks
Playback
Eq, SW — 70 us Play back and read the wow/flutter meter.
4.2.
Playback
Frequency
Response
Adjustment
R
RIO
R195
Figs,
4.1
and
4.2
show
the
playback
amp,
circuit
for
adjustment
R/P
ya
(nzash
and
the
playback
equalization
curve.
Head
This
adjustment
will
be
required
if
playback
level] is
not
sufficient
during playing back a 20 kHz PB frequency response tape.
The peaking portion of the equalization curve compensates the
gap
loss
of
the
playback
head.
Peaking
level
is
varied
by
the
short
120ps
circuit
of
R110
(R210)
or
R195
(R295).
Lol
{L20)
VRION
(VR201)
Output
390P
Hi
C107 (C207)
C108 {C208} 1000P
GAIN (dB)
100 400 1K 2K 10K 20K
FREQUENCY (Hz)
Fig. 4.2

4.3. Dolby NR Circuit Check
Dolby NR circuit incorporates a Dolby NR IC (ZA7300PC) which
has no adjustment point.
Perform the following checks and make sure that the IC operates
accurately ie., frequency response through IC is accurate.
(1)
(2)
(3)
Signal Source: 1.4 kHz to Input Jacks
Output Connection: VTVM to TP101 (TP201) and
negative side of C141 (C241) on the
Main P.C.B.
Mode: Record/Pause
Connect a VTVM to TP101 (TP201) on the Main P.C.B.
Ass’'y, Feed in 1.4 kHz and adjust the Input level control so
that the VTVM may read 90 mV (0 GB) at each test point.
Level meter will indicate 0 dB.
Remove the VTVM from TP101 (TP201) and reconnect it to
the negative side of C141 (C241).
Decrease the input level (0 dB) by 20 dB or 30 dB.
Check to insure that the level at negative side of C141 (C241)
corresponds to the following with the Dolby NR switch ON
and OFF.
Input Level Level at negative side of C141 (C241)
at TP101 (TP201) | Dolby NR OFF | Dolby NR B-Type
9mV OdB +3.2 dB +1.5 dB
2.85 mV 0 dB +8.2 dB +1.5 dB

MECHANISM ASS’Y AND PARTS LIST
5.
5.1. Synthesis
Fig. 5.1