Nakamichi BX-300 User manual

Nakamichi
Service Manual
Nakamichi
BX-300
BX-S3O00E
Discrete Head Cassette Deck

CONTENTS
2.
3.
10.
11.
12.
Goeme rll, 55.5.5 e cree tae Se I foe NS We ce SS Goes Bie We eS Sele Sen late BS Bik: 8 eo br ede aed 2
Test Tapes and Gauges: es. oic8 sie les sits a paced who Ta 0 a as Biles oe bE Bile eed Ow) and a dle ae ik OG ate BE Bk Sao aM 2
Mechanical Adjustment’ .....6. 5.46068 ee 68 be 8 8 ee Sete © Rees a Beer a Da deane eG Bere eee hae 3
3. #1. Record Head and Playback Head Tilt Adjustment ...........0. 0... cc eevee eee ene eene 3
3. 2 Head: Base:Stroke: Cheek: $0537.66 20 asad & Sacto Ghd bat See ew ata BS She Bata? Np eed Ec gal bel bo 3
3. 3 Erase Head Stroke Adjustment and Tape Guide Height Check ...................200c0ee 3
3. 4 Erase Head Height and Tilt Adjustment ........ 0.00... cece eee ee ee eee eee eee 4
3. 5 Playback Head and Record Head Height Adjustment and Azimuth Alignment ............... 4
3. 6 Pressure Adjustment of Take-up Pressure Roller... 0.0... 0.0.0.0 ccc eee ec eee eeeeenes 5
3. #7 Tape-Travelling Check. s..5 6 c.556 cs aie ee Goa 6 Serene 4 We lg hehe Bes Mel a, HSE a) Siw Be Sata SEL 5
3. 8 Eject Damper Adjustment ........... cc eee ee eee ee eee ee eee eee eet eee 5
3. 9 Reel Motor Speed Adjustment in Play Mode ............ 0... ccc ee tee cee ee ee eae 5
3. 10. Tape Speed Adjustment ..2 6 io5.12.. ioe ee is Se he veces Sata BE Aw boo BRIE Soe le bw Dd Wer bebe ees 5
3. 11. Mitt Drica tion o.5 se. eh eh ee ele aoe aig Bae eRe Sasa Narre a hn de Dee Ode cba Rs BE Bae a 5
Parts Location for Electrical Adjustment... 2... .. 00.00. cee ee eee ee tee twee eee aes 6
Electrical Adjustments... o5:605. 6.606 bse eee bio ene 88, ER Se ww UAE Law! Ow A eee wee Bile Sig ee Gus ewe ew a 7
5. 1. Adjustment Instructions .. 0.0.2... 0... ccc ee eee eee eee ee eee eee wees 7
5. 2. Playback Frequency Response ......... 0... cc cece eee ce eee eee ee tee eee tee e ens 9
Mechanism Ass’y and Parts List... 2... ee ee tee eee te eee eee e nett e ee aee 10
6. 1. Synthesis: <seSsrah piece Samad wine eee seed ae: die na arc hat BP tec ibxk bite, aR Hn ah Pie oa eR tie gee 10
6. 2. Front:Panel; Ass’y (AOL). esos oo 68 06 oe Bi wie ee bee Sa) WOE Cea eae ere ene wa ae MS RS wees 11
6. 3. Synthesis Mechanism Ass’y (A02) .. 0... cc ee ee eee tw ee eee eee eee ene 11
6. 4. Front: Chassis Ass’y:(BO1)..6 go ei6. bn Poe Secs d Ww SOE ee nk, Ea a ee ae So De 12
6. 5. Cover: Plate Ass’y (BOQ): (ois ic hccono oes hiaiar Gea aeS ele Pe Se aust Sw) bs, ig Bw Ss 0d a ay bod fend wives Boece 13
6. 6. Mechanism: Ass’¥ (BOS). 5.5 o..scsyrsicarce ed ee 4 co oe a Ra Ow RH ISIWY Hew wile oh Gor NESS Ves wn we gael ioled ve 14
6. 7. Rear'PanelAss’y (B04) cc ccc 6 ee eee die 8 we wh See OE Ne ee WO ele ew See So Oe aw 15
Mounting Diagrams and Parts List .. 2... 1. ee ete ee ee ete ee tenet e ete e ees 15
7 1. Power Switch P.C.B: Ass’ 63 6 ésec5: oe lie be a a as BEN ale. rd, IS iw Wels LTR Se ee See erate 15
7 2. Shut-off:P:C:BcAss' yo o5o sch Relea BA Nen ok obra WOR RUS EE ibe alae ORL ala Slee ace be eee 15
7. 3. Fuse: P:C:B: Assy c5 2.5 op co S conte at, epee ew 5b, FG e BARI bo wi ew ol lon aH la vaso ates Heats a EOI 16
7. 4. Volume'P.C.B: Ase’ y <4 secen3 seis a toss eta See OS be a tigs atte leas Bea ee ca te ia ara ty BOR Gabe teaarer ed ae 16
7. 65. Input:Amp: P:C{B. Ass?y sesso cece oe See wn ek earns, Sut S, Wig foi Boe BS RE wee ee ee meena le Stennis 17
7. 6. Meter Amp.-P:C:BiAss’Y 66054 52h b Sie 0k hale eRe Beg e Oa Na OR Be bl esate ena ORS RIAA ES 17
7. 7%, Dolby NR: Switch: P:C.B: Assy. ie oi6: 6 see ieee ewok ae ohn Bik 0 Uae Rg ee Ta a aes er EN ah bok 17
7. 8. Control Switch P.C-B: Assy 3265 ssc2 3, ce, 6s ea sw Oe, ben Wine. BAS wR RAG SUR re BS BS RG 18
7. 9. Counter PCB. Assy sii diss. os; 5) 200 ose enh ose Se ren 0 ese Oo Benw wren aie Ooa Sea 6 OMe Wiles a back wd eT Kae 18
7. 10. Tape Switch:P:C. Bi Assy 232 sicsse 5.6 aire a ee Se oie ae. Hal TOS. dee ele goa fever Bo 8 a wea glare 18
7. 11. Main PC BAgs ty tock eee a5 aid beak ee oe lara s ee ee Sa EG See WED ae WR ed ORS. CUS patente 19
Schematic Diagrams .......... MM eae Naser Shenae Si rbica Welw ere maiielalcaladhce tenis. varvesien dcectel wicyloue folie erie ateiie ie) ar aneree an 23
8. 1. IC: Block: Diagrams <2 6266610 ies Ps sie Wak! oa hans Ss a ee gh Be. Gdal eRe Blea COG ahs, Gidea ware 23
8. 2. Schematic: Diagrams: > 535.5 d0.l5 ae ch aco: Siew ae Ceara word Blea dane Wa Ss See we ward ate, bw eles 24
Timing Chart and Eq. Amp. Frequency Response .......... 0.0 cece eee eee ewe tenet eee ee eeee 26
9. 1. Timing: Chart: io. ooo ood Giese aie bi wine: GR Se aA Baal hin Oey ol wid, tae eb ok eS OSE et Alas bad A ee ea 26
9. 2, Eq. Amp. Frequency Response .. 1.0.0.2... 0c cece ee eee eee eee eee teen e eee eee 26
Wiring: Diagram isis i ison 5 8 Sie cn bb ass ews ls cat aa as ira 9ve a tach ot ply SOTO ebay WSL OE Ga @ aa ahi elias 27
Bl OG; Dia eras: «55. ieee. so Seco ig.r8 gb! oS. A/G AS 9 col 6a eRe SSS gs we Sd Riad Wha ao, Ovorar ks 1aw, BNO led Mea a gee dees 28
11, #1. Amplifier:Seetionn i535.) es ecesaces gs eerie: seesaw. ak ap afer bh ab a Shag, cede Eira at Talvasv, Sa be) ei aca lep glen Sow facsds aie e 28
11. 2. Mechanism Control Section ....... 0... . ee ee ee tee et ete ee eee eee eens 29
Specifications ics: Ses eh hy, 58 as Fe te. Sy BS SEE SE Cia Rory wha ea) 8 lg: Meal Geer os ad “ah dca acaners 30

1. GENERAL
1.1, Voltage Selector
Voltage selector is installed on the rear panel for Other version of the Nakamichi BX-300.
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
OF03812A Carton Box BX-300 (U.S.A., Canada, Australia & Others)
OFO03821A Carton Box BX-300 (Japan)
OF03813A Carton Box BX-300E
OF03674C Packing
DAO3800A Extension Cord
0D04450A Owner’s Manual BX-300 (U.S.A., Canada & Australia)
0D04451A Owner’s Manual BX-300 (Japan)
DA03801A Owner’s Manual BX-300E & BX-300 (Others)
2. TEST TAPES AND GAUGES
(1) 400 Hz Level Tape (DA09005B)
(2) 1kHz Track Alignment B Tape (DA09087B)
(3) 10 kHz PB Frequency Response Tape (DA09003B)
(4) 15 kHz PB Frequency Response Tape (DA09002B)
(5) 20 kHz PB Frequency Response Tape (DA09001B)
(6) 15 kHz Azimuth Tape (DA09004B)
(7) 3kHz Speed and Wow/Flutter Tape (DA09006C)
(8) Tape Travelling Cassette (DA09071A)
(9) Reference EXII Tape (DA09066B)
(10) Reference SX Tape (DA09025B)
(11) Reference SX-E Tape (DA09086A)
(12) Reference ZX Tape (DA09037B)
(18) EH Tilt Check Gauge S (DA09088A)
(14) Stroke Check Gauge S (DA09090A)
(15) Tape Guide Height Check Gauge S (DA09091A)
(16) Tilt Check Gauge S (DA09039B)
(>)
BRE RN ERE]
“¢

3.
MECHANICAL
ADJUSTMENT
3.1,
Record
Head
and
Playback
Head
Tilt
Adjustment
Remove
the
Cover
Plate
Ass’y
by
loosening
two
screws,
Refer to Fig. 3.1.
(1)
Remove
the
pad
lifter
from
the
playback
head.
(2)
Load
a
Tilt
Check
Gauge
S
in
the
cassette
deck,
(3)
Clip
the
grounding
terminal
of
the
Tilt
Check
Gauge
with
one
end
of
the
cord
with
clip,
and
the
chassis
of
the
cassette
deck
with
the
other
end.
(4) Remove both of the Height Gears,
(5)
Set
the
cassette
deck
in
Play
mode.
Check
to
insure
whether
the
Beacons
Playback
Head
“Upper”
or
“Lower”
and
Record
“Head
“Upper”
or
“Lower”
are
illuminating.
In
order
not
to
give
damages
onto
the
head
surfaces,
push
both
of
slide
knobs
of
the
Gauge
to
away
from
the
heads,
then
return
them
to
the
original
place
to
be
in
contact
with
record
head
and
playback
head
surfaces
after
Play
mode
is
securely
locked.
(6)
Beacon
Playback
Head
*“‘Lower’’
will
light
on
when
height
.
adjustment
screw
(PH)
turned
counterclockwise
but
Play-
back
Head
“‘Upper’
when
clockwise.
Adjust
so
that
both
“Upper”
and
“Lower”
will
light
on
even
when
you
move
the
slide
knob
away
from
the
heads
and
then
return
it
to
the
original
place.
(7)
Same
procedures
will
apply
to
the
Beacons
Record
Head
“Upper”
and
“Lower’’,
except
for
the
height
adjustment
screw
(RH).
(8)
Set
the
cassette
deck
in
Stop
mode
and
fit
both
of
the
serrated
Height
Gears.
Then
set
the
cassette
deck
again
in
Play
mode
and
insure
all
of
the
4
Beacons
are
illuminating.
If
not,
(4)
through
(7)
will
have
to
be
repeated
till
satisfactory
results
are
obtained.
(9)
Mount
the
pad
lifter
on
the
playback
head.
3.2. Head Base Stroke Check
Remove the Cover Plate Ass’y.
Refer to Fig. 3.2.
Note:
Before
you
conduct
this
adjustment,
adjust
with
a
“Tilt
Check
Gauge
S”
to
insure
freedom
from
tilt
on
the
play-
back
head
and
record
head.
(1)
Load
a
Stroke
Check
Gauge
S
in
the
cassette
deck,
(2)
Move
Record
Head
Indicator
and
Playback
Head
Indicator
to
the
direction
of
arrow
mark
“A”
with
your
finger
tip
and
then
set
the
cassette
deck
in
Play
mode.
Then
slowly
release
the
Indicators
and
insure
whether
each
of
the
Indicators
is
in
contact
with
record
and
playback
heads.
(3)
Check
to
insure
whether
the
line
“P”
on
the
Playback
Head
Indicator
meets
the
central
line
on
the
Indicator
Plate.
(4)
Check
to
insure
whether
the
line
“P”
on
the
Playback
Head
Indicator
locates
between
the
2
lines
on
the
Record
Head
Indicator,
thus
check
can
be
made
on
record
head
stroke.
3.3.
Erase
Head
Stroke
Adjustment
and
Tape
Guide
Height
Check
Remove
the
Head
Mount
Base
Ass’y
and
the
Cover
Plate
Ass’y,
Refer
to
Fig.
3.3.
(1) Erase Head Stroke Adjustment
(a)
Load
a
Tape
Guide
Height
Check
Gauge
S
in
the
cassette
deck,
(b)
Set
the
cassette
deck
in
Play
mode,
thus
check
can
be
made
on
erase
head
stroke
through
the
EH
Stroke
Indicator,
(ec)
Check
to
insure
whether
the
erase
head
surface
is
aligned
with
red
line
on
the
EH
Stroke
Indicator.
If
not,
adjust
the
erase
head
stroke
by
loosening
screw
A
that
assembles
erase
head
with
erase
head
plate.
(d)
After
completion
of
adjustment,
screw
A
shall
be
locked
with
lock
tight
paint,
(2) Supply Tape Guide Height Check
(a)
Load
a
Tape
Guide
Height
Check
Gauge
§
in
the
cassette
deck,
(b) Set the cassette deck in Play mode,
(c)
Slide
the
Supply
Tape
Guide
Check
Bar
down
against
the
supply
tape
guide,
and
check
to
insure
that
the
Supply
Tape
Guide
Check
Bar
is
accepted
by
the
supply
tape
guide.
(3) Take-up Tape Guide Height Check
(a)
Load
a
Tape
Guide
Height
Check
Gauge
S
in
the
cassette
deck.
(b) Set the cassette deck in Play mode,
(c)
Slide
the
Take-up
Tape
Guide
Check
Bar
down
against
the
take-up
tape
guide,
and
check
to
insure
that
the
Take-up
‘Tape
Guide
Check
Bar
is
accepted
by
the
take-up
tape
guide.
Height
Gear Stopper (RH)
Height Geor (RH)
Height Geor (PH)
Play Mode
Fig, 3.3
Height Adj, Screws(PH!
Take-up Tape Guide Check Bar

3.4. Erase Head Height and Tilt Adjustment
Refer to Fig. 3.4.
qd)
(2)
(3)
(4)
(5)
Remove the Cassette Case Ass’y, Head Mount Base Ass’y and
Cover Plate Ass’y.
Load an EH Tilt Check Gauge S in the cassette deck.
Set the cassette deck in Stop mode.
Check to insure whether one of the 3 Beacons is illuminating.
Look down the mirror and slowly turn the Screw “Height”
counterclockwise (or clockwise) so that the two horizontal
lines on the mirror will become superposed on the line (in
different color) of the erase head, and check to insure
whether the first Beacon is illuminating.
Turn Screw “Tilt” counterclockwise (or clockwise) to light
on the second Beacon, Excessive turing will] cause the first
(6)
(7)
(8)
Beacon to light off, Adjustments of Screw “Tilt” will there-
fore be conducted till both of the first and the second
Beacons iJuminate.
Turn Screw “Azimuth” counterclockwise (or clockwise) to
light on the third Beacon, Excessive turning will cause either
the first or the second Beacon to light off, and therefore
adjust Screw “‘Azimuth’’ until all of the 3 Beacons illuminate.
Check to insure whether the horizontal line on the mirror
corresponds 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 pes. of screws shall be
locked with lock tight paint.
Note:
Before
use
of
this
gauge,
check
to
insure
freedom
from
dust
Fig. 3.4
3.5. Playback Head and Record Head Height Adjustment and (2)
Azimuth Alignment (a)
Refer
to
Fig.
3.5.
(b)
(1)
(a)
b)
(ec)
(a)
(e)
(f)
Playback Head Height Adjustment and Azimuth Alignment
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 optimum performance.
PHHeight Adjustment
PH Azimuth Alignment
(c)
(a)
(e)
69)
(8)
or dirts, or overflow in the groove of the erase head surface.
Record Head Height Adjustment and Azimuth Alignment
Set the cassette deck in Stop mode.
Set the Monitor switch to Tape, Eq. switch to 70 és 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 turn the
RH Height Gear until the 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 Height Adjustment
RH Azimuth Alignment
Fig. 3.5

3.6, Pressure Adjustment of Take-up Pressure Roller
Refer to Fig. 3.6.
(1) Set the cassette deck in Play mode,
(2) Measure the torque of the Take-up Pressure Roller and check
whether the torque is in a range of 320 +50 g-cm.
(3) If torque is out of the range, correct it by changing the instal-
lation point of the Pressure Roller Spring.
Fig. 3.6
3.7. Tape Travelling Check
Load and playback a Tape Travelling Cassette and check the
following:
(1) Tape is in contact with heads sufficiently.
(2) Tape waving is small on the heads and pressure rollers.
(3) Tape is free from waving or slippage from the tape guides.
3.8. Eject Damper Adjustment
Refer to Fig. 3.8. 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 action by the Adjustment Screw.
Fig. 3.8
3.9. 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.
3.10. Tape Speed Adjustment
Refer to Fig, 3.9.
(1) Set the Pitch Control Knob on the Front Panel to its mechan-
ical center position.
(2) Connect a frequency counter to the Output Jacks,
(3) Load a 3 kHz Speed and Wow/Flutter Tape and play it back,
(4) Adjust VR101 on the Motor P.C.B. Ass’y to obtain 3,000 Hz
on the frequency counter.
CCW: Motor drives fast.
Cw: Motor drives slowly.
a
2
a
2
Q
Q
Q
5
Dd
Increase ar
Motor PC.8. Assy
Decrease
Fig. 3.9
3.11. Lubrication
The tape transport is of a lubrication-free type mechanism. When
the following parts are replaced, apply the specified lubricant.
(1) Molykote @) 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,
Chiyoda-ku, Tokyo, Japan
(c) Diamond Oil (EP-56)
Mitsubishi Oil 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

4. PARTS LOCATION FOR ELECTRICAL ADJUSTMENT
Main PC.B.
VRI01 VR201
Playback Level
6)
VR60I
rPeaking
Reel
Motor
Speed
(Play)
L102
L204
MPX Filter
T _
:
Bias Trop
(Record)
TP202©)
TP201@
TP101I®
TP102©
L108
[oe]
L104
VR202
VR204
& s[9]
©L
(QL vazos
CL
EX
x
zx Record Level
3
18) 19
vR102
VRI03
VRI04
Meter Amp.P C.B.
Tape Switch P C.B.
Fig. 4

5. ELECTRICAL ADJUSTMENTS
Notes: 1. Electrical adjustment should be performed after mechanical adjustment is completed.
2.
Before
adjustment,
set
the
Bias
Tune
control
and
the
Pitch
control
on
the
Front
Panel
to
their
mechanical
center
positions,
5.1. Adjustment Instructions
REMARKS
1,
Set
the
Pitch
Control
to
its
mechanical
center
position.
2. Adjust VR101 to obtain 3 kHz +0.5% on
the frequency counter,
Output Jacks MPX SW -—ON
Input Jacks
Play back
1 kHz Track Monitor SW — Tape
VTVM to Eq, SW — 70 us
Alignment B
Tape Output Jacks =| Dolby NR SW — OFF
MPX SW — OFF
Playback
Head Track
Playback
Monitor SW — Tape
Eq. SW — 70 us
Dolby NR SW — OFF
MPX SW — OFF
VTVM to
Output Jacks
Head 15 kHz
Azimuth Tape
Evpene
400
Hz
Level
VTVM
to
Calibration
|
T@Pe
Output
Jacks
Same as above
400 Hz Level
Playback
Frequency Monitor SW — Tape
Frequency | Response Tape | yryn to Tape SW — SX
15 kHz PB
t Frequency
Response Tape
20 kHz PB
Frequency
Response Tape
Output Jacks Eq. SW — 70us
Dolby NR SW — OFF
MPX SW — OFF
Response
Adjustmen
SIGNAL OUTPUT ADJUST-
STEP ITEM SOURCE | CONNECTION MODE MENT
3 kHz Speed
1 Tape Speed | and olson Play back Motor P.C.B.
Adjustment | Wow/Flutter Output Jacks Eq. SW — 70 us VR101
Tape P
Meter Amp.
Meter Level | 400 Hz to VTVM to F a
2 Calibration | Input Jacks Output Jacks Monitor SW — Source is 108.VR 208 r
5.
+
2
: 19 kHz +100 Monitor SW — Source A
MPX Filter VTVM to Main P.C.B.
3
Adjustment
Hz
to
Dolby
NR
SW
—
OFF
L102,L202
3.
PH Height Gear
Playback Head
Azimuth
Alignment
Screw
Main P.C.B.
VR101,VR201
Main P.C,B.
R109,R209
R110,R210
1. Set the Output Level control to max.
2. Feed in 400 Hz, then adjust the Input Level
controls to obtain 1.0 V ~—4 dB on the
VTVM.
3. Adjust VR108 (VR208) so that the 0 dB
segment of the level meter starts to il-
luminate,
Adjust the Input Level control to obtain
1.0 V +1 dB on the VTVM and check
to insure that the upper segment of the
O dB segment starts to illuminate.
Set the Output Level control to max,
. Adjust the Input Level controls to obtain 1
V on the VTVM.
Set the MPX Filter switch to ON, then
adjust L102 (L202) to obtain the minimum
reading on the VTVM (the minimum read-
ing will be less than —30 dB),
Adjust the PH Height Gear to obtain minimum
readings for both channels on the VT VM. Refer
to “Playback Head Height Adjustment and
Azimuth Alignment” in item 3.5,
Adjust the Playback Head Azimuth Alignment
Screw to obtain maximum readings of both
channels on the VTVM, Refer to “Playback
Head Height Adjustment and Azimuth Align-
ment” in item 3.5.
Note: Repeat steps 4 and 5 one or two times to
obtain optimum performance,
1. Set the Output Level control to max.
2. Adjust VR101 (VR201) to obtain 1.0 V on
the VTVM.
. Load a 400 Hz level tape and play it back.
Adjust the Output Level control to a certain
level (0 dB for example),
2, Load 10 kHz, 15 kHz and 20 kHz PB fre-
quency response tapes and adjust the play-
back head azimuth to obtain maximum
levels on the VTVM with each tape.
Short R109 (R209) and/or R110 (R210) to
obtain the following levels against the level
for the 400 Hz level tape.
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 ‘Playback Frequency Response
Adjustment”’ in item 5,2.
3. Conduct step 5 “Playback Head Azimuth
i ent’’.
VTVM across
the additional Record, Pause
0.1 2 resistor Monitor SW — Source
Oscillation
Frequency and Tape SW — ZX
and Erase Frequency Eq. SW — 70 us
Current Counter to Dolby NR SW — OFF
Adjustment CN3-lon Tape |MPX SW —-OFF
Switch P.C.B,
Record
Amplifier
Pha
Equalizer
|
(—20
dB)
to
Adjustment
|
put
Jacks
VTVM to
TP101, TP201
on Main P.C.B.
Same as above
Bias Trap
Adjustment | Remove
(Record input signals
VTVM to
TP102, TP202
on Main P.C.B.
Same as above
Tape Switch
P.C.B.
T301
R301,R302
Main P.C,B.
L104,L204
1, Connect an additional 0.1 2 resistor in
series to the Erase Head, then connect a
VTVM across the resistor.
2. Adjust T301 to obtain 105 kHz on the fre-
quency counter,
3. Check the erase current by the VTVM.
Erase current will be in a range of 310 mA
to 400 mA (typically approx. 350 mA). If
erase current is not sufficient, increase it by
shoring either R301 or R302.
4. After completion of the erase current
adjustment, re-check the bias oscillation
frequency.
. Remove the additional 0.1 © resistor.
5
1. Remove the bias-cut-jumper from the dip
side of the Tape Switch P.C.B. Ass’y.
2, Adjust L104 (L204) to obtain approx. +16
dB at 23 kHz on the VTVM.
3. Re-solder the bias-cut-jumper.
Main P.C.B.
L105,L205
Adjust L105 (L205) to obtain minimum read-
ing on the VT VM.

Record, Playback
Monitor SW — Tape
Tape SW — ZX
Eq. SW — 70 us
Dolby NR SW — OFF
MPX SW — OFF
VTVM to
Output Jacks
400 Hz (0 dB)
to Input Jacks
11 Head Height RH Height Gear
Adjustment
to
Record
< 15 kHz (—20 Record Head
12 Head dB) to Input bra eis . ck Same as above Azimuth
Azimuth Jacks urpUswacks Alignment Screw
Alignment
1.
2.
3.
4,
Main P.C.B.
(Level)
Record, Playback ZX:
Tone — 400 Hz/ VR104,VR204
15 kHz Sx:
Record
Monitor
SW
—
Source/|
VR103,VR203
7.
Level
400
Hz
and
Tape
EX:
Calibration as ae VTVM and Tape SW — BxISe! VR102,VR202
18
|
and
10
kHz/20
Dig
rion
Meer
ng
sw
=
70
ps
Tape
Switch
Recording
|
x+12
(—20
dp)
|
*
Output
Jacks
(ZX/SX)
|P.C.B
8
Adjustment | ‘© Input Jacks 120 us (EX)| (Biss)
Dolby NR SW — X:
C-Type/B-Type/
OFF
MPX SW — OFF
VR107,VR207
SX:
VR106,VR206
EX:
VR105,VR205 1/11,
Record, Playback
Monitor SW — Source/
Tape
Tape SW — ZX/SX/EX
Overall 400 Hz (0 dB)
d 20 Hz to A
Frequency | 22 VTVM to _ Main P.C.B.
14 [Response | 20072 4. [Output Jacks | Ba. SW (2kisxy | 1104,L204 é
Adjustment | Faout Jacks 120 us (EX) :
Dolby NR SW — OFF
MPX SW — OFF 7
8
SIGNAL OUTPUT ADJUST-
sree | em SOURCE CONNECTION MODE MENT REMARKS
Adjust the RH Height Gear to obtain maximum
readings of both channels on the VTVM. Refer
Azimuth Alignment” in item 3.5,
Adjust the Record Head Azimuth Alignment
Screw to obtain maximum readings of both
channels on the VT VM. Refer to “Record Head
Height Adjustment and Azimuth Alignment” in
item 3.5,
Note: Repeat steps 11 and 12 one or two times
Adjustment should be made in the order of ZX,
SX and EX.
. Adjust Record Cal! VR104 (VR204) for
- Feed in 400 Hz (0 dB), then record and play
. Check to insure whether the total harmonic
. If above is not sufficient, repeat 6 to 14 till
. Set the Monitor switch to Source.
- Conduct step 13 “Record Level Calibration
. If above is not sufficient, precise re-adjust-
“Record Head Height Adjustment and
to obtain optimum performance.
Set the Monitor switch to Source and Dolby
NR switch to C-Type.
Feed in 400 Hz, then set the Input Level
controls to obtain 0 dB (1 V) on the VTVM.
Set the Monitor switch to Tape.
Load a reference ZX tape, reference SX or
SX-E (for BX-300E) tape and reference
EXII tape.
ZX, VR103 (VR203) for SX and VR102
(VR202) for EX to center position,
it back.
Adjust Bias VR107 (VR207) for ZX,
VR106 (VR206) for SX and VR105
(VR205) for EX to obtain the maximum
readings on the VTVM.
Feed in 15 kHz (—20 dB), then adjust Bias
VR107 (VR207), VR106 (VR206) and
VR105 (VR205) to obtain the same
readings as source monitor levels on the
VTVM.
Feed in 400 Hz (0 dB), then adjust Record
Cal, VR104 (VR204), VR103 (VR203) and
VR102 (VR202) to obtain 0 dB on the
VTVM.
Repeat above 7 and 8 two or three times to
obtain optimum performance.
Set the Dolby NR switch to OFF.
Feed in 10 kHz (—20 dB) and 20 kHz (—20
dB), then record and play them back, Check
to insure that the levels are within —20 dB
+3 dB against the levels in Dolby NR
C-Type.
Set the Dolby NR switch to B-Type.
Feed in 10 kHz (—20 dB) and 20 kHz (—20
dB), then record and play them back. Check
to insure that the levels are within —20 dB
+3 dB against the levels in Dolby NR OFF.
distortion is less than 0.9% for ZX tape and
1,0% for SX/SX-E and EXII tapes.
satisfactory results are obtained.
Feed in 400 Hz (0 dB) and adjust the Input
Level controls to obtain 0 dB (1 V) on the
VTVM.
pha the Generator output level to —20
B.
Set the Monitor switch to Tape, then record
and play it back.
Feed in 20 Hz to 20 kHz (—20 dB), and
check to insure whether the output levels
are within —20 dB +3 dB.
If above is not sufficient, adjust L104
(L204) to obtain approx. —20 dB on the
VTVM at 20 kHz.
and Recording Bias Current Adjustment’,
ment of step 7 “Playback Frequency
Response’’, replacement of Playback Head
or Record Head, check on item 3.7 “Tape
Travelling Check’ will be required.

5.2, Playback Frequency Response Adjustment The peaking portion of the equalization curve compensates the
Figs,
5.1
and
5.2
show
the
playback
amp.
circuit
for
adjusment
gap
loss
of
the
playback
head.
Peaking
level
is
varied
by
the
short
and
the
playback
equalization
curve.
circuit
of
R109
(R209)
and/or
R110
(R210)
on
the
Main
P.C.B.
This adjustment
will be
required
if
playback level is
not
sufficient
Ass’y.
during playing back a 20 kHz PB frequency response tape.
R109 R110 L101
(R209) (R210) ar laaiaass
390 3= 68
Play back
Head
Fig. 5.1
GAIN (dB)
approx. 2dB
approx. 2d8
approx. 2dB
FREQUENCY (Hz)
Fig. 5.2