JVC MIK-100 User manual

MODEL
MIK-100
CASSETTE RECORDER
No. 0002
April 1978

MK-100
Contents
Page
SPECIFICATION: «e050 oe Ser sor See Face, une ew ee Sede bse eles Pe as yb ee Bat eens bo AAO, 2
FO@atUTES oe closes fo ee a reeees hacen een he ede ib oR ie ee Gwe tk A ad ee i wc enn 3
Names ot Parts: > nc. te es ee eo SS ty Rk ee SE ee hE Ge ee at es oe, © 3
Disassembly and Replacement ........0.. 0 eet ee ee ee ee ke ee 4
Mechanical Adjustments and Repairs .........00 00 cee ee ee ee ee ee te eek he te ee 7
Technical Information . 2... 2... 2c ee ee et tee ees 9
Adjusting Recording Bias .. 2... 0 ee ee ee ee ee 11
Cleaning and Lubrication .. 1... 1. 1 ee ee ee es 11
Before Services is. ieet es cre a Be, ial eee eS on te, ae Bed ew a oS ie oe hates aes 11
Block Diagram: jievis: se nies da ee GES a Pa Rene ars, we Gas Sw Bee a anak & aed ees 12
schematic Diagrams: és. i825.5. 60 oe ee woe a, Bi Ce sa ae WS eee Se ee ea a 13
WIRING) 6c ss oe. ov See eee, Ge SBOE Sa hE Res, alien wren. Been Oh hh ee a 14
Circuit: Board Parts: <<. 3. asad i Gece we Sei eS we eco, See Hy be G FS bred aha. eee ce wae ae St 15
Mechanical Components .........0 0.0. ee ee eee ee ee es 17
Total Assembly =<: 6:63. 3.96 See ite ete eve oe & eh eda Ogi ala Eee es eats bed Sa 19
Packing nc. 3 chose ee ea th. he td eaertaec a Oe: Tact, Se tads Le ater Merapoieh erate MER Cars tee tae, Ae fone eR a 22
AGCESSOVICS 55.55: Sid hee Gg ieee ans Teena lapis Wan ot we eee ee ee GE we Pe: Cay BAR ere ak a ee lee ait ccaly 22
Specification
DIMENSIONS :
Type
Tape speed
Track system
Recording system
Erasing system
Cassette
Fast forward time
Rewind time
Wow & flutter
Frequency response :
Semiconductors
Speaker
Power output
No. 0002
81.5mm(W) x 179mm(H) x 28mm(D)
3-3/16""(W) x 7“(H) x 1-1/8"(D)
Compact cassette recorder
4.8cm/s (1-7/8 ips)
2-track, monaural
AC bias, ALC
DC erase
Philips type compact cassette
Within 120sec. (C-60 cassette)
Within 140sec. (C-60 cassette)
0.25% wrms
300 — 8,000Hz
1 IC, 18 transistors
5cm (2) Samarium cobalt speaker
350mW at 1kHz
WEIGHT :
Input jacks
Output jacks
Power supply
Battery life
500g with batteries
1.1 Ibs.
Approx.
MIC; sensitivity O.3mV accepts
a low impedance microphone.
DC IN (6V)
EAR, REMOTE
DC 6V (4”AA" batteries)
AC (using the AC adaptor)
Car battery (using the car adaptor)
Continuous recording time with
the built-in microphone; approx.
2.5 hours with the super type
battery SUM-3 (size AA)

MK-100
Features
® Ultra-thin, ultra-compact design — a portable of portables designed to fit the palm of your hand.
A single sliding knob controls tape start, stop and rewind, permitting simple, single-hand operation.
™ Three LED recording level indicators, one of which also functions as a battery checker, assure you of the best possible
recordings.
= A microphone sensitivity select switch allows optimum recordings of both dictations and conferences, together with the
ALC (Automatic Level Control) circuit.
@ A newly developed ultra-thin speaker having a diameter of 50mm and incorporating a powerful samarium cobalt magnet
achieves outstanding sound quality.
= Auto-stop mechanism stops the motor at the end of the tape during recording, playback or rewind.
Also a warning tone is heard at the tape’s end, sparing of battery power.
m The stand-by mechanism allows starting a recording at a precise point, saving tape consumption.
@ Three-digit tape counter helps in locating the beginning of a particular tape section.
Names of Parts
Fig. 1
1 Remote control jack (REMOTE) 10 Sensitivity select switch (HIGH/NORM)
2 External microphone jack (MIC) 11 Earphone jack (EAR)
3 Built-in condenser microphone 12 Security strap
4 Counter reset button 13 External DC input jack (DC IN 6V)
5 LED indicators 14 Volume control knob (VOL)
6 Tape counter 15 Record button (REC)
7 Slide control knob 16 EJECT/REVIEW button
8 Speaker 17. FF/CUE button
9 Cassette compartment 18 Battery compartment
cae. ee No. 0002

MK-100
Disassembly and Replacement
The MK-100 which features an ultra-compact design and high performance uses miniature-sized parts which are closely
arranged. Use special care when servicing it.
Enclosure
Parts Name Procedure Ref. No. Description
Bottom panel Remove four mounting screws and then remove the bottom Fig. 3 @) SPSK2003M (Black)
panel. SPSK2003N (Silver)
5 eerie
Top panel Remove five screws and then remove the top panel. Fig. 2,3 @) | SPSK2003M(Black)
SPSK2003N (Silver)
=
Front panel 1. Pull out the control knob.
2. Remove two screws and then remove the front panel. Fig. 2 @) SPSK2003M (Black)
Rear panel 1. Remove two screws. Fig.3 @ SPSK2003M (Black)
2. Remove one screw and pull out the security strap. Fig.3 ® SPSK2004M (Black)
3. Then remove the rear panel.
=
Inner-lay and . Remove four screws and then remove the cassette lid ass’y. Fig. 4 © SPSK2003M (Black)
cassette lid 2. Then put out the hinge shaft. SPSK2003N (Silver)
Note: When disassembling the panel, take care not to scratch it.
Electric parts
Parts Name Procedure Description
Circuit board 1. Remove the bottom panel, front panel, control knob, top panel See ‘Enclosure’ sec-
and rear panel. tion.
2. Then remove three screws. SPSK2004N
Note: When removing the circuit board, if you set the circuit
board up by a screw-driver keeping the leaf switch away
from the F.F. button, removing is very easy.
. Remove seven wires and one diode soldered to circuit board.
Then remove circuit board ass’y.
When installing the circuit board, please install it after the
slide switch for PLAY/RECORD is switched over to the
play position.
Sub-board Remove one screw and raise the sub-board. F004 10-235M
No. 0002

MK-100
Control Knob Security strap
Fig. 2 Fig. 3
©) @) ©® Sub board
Hinge
shaft
Amp.
circuit
board
7
Fig.
4
YY
@
Fig.
5
E.
governor
board
— BLK
—_—___———_ oRN
#—-——- BLUE (Governor)
‘ RED
| *———_ YLW (two wires)
, = BLUE (Speaker)
Diode
R/P switch
Fig. 6 Fig. 7
— No, 0002

MK-100 |
Mechanical parts
Parts Name Procedure Ref. No.
|
Remarks
Mecha. ass’y Remove two screws. Fig.4 @ SPSK2004N
Then the Meca. ass’y can be separated from the battery case
ass’y.
1. Remove two screws and then remove the motor and motor Fig. 8 SPSK2045M Motor
bracket.
2. Remove two screws. Fig.9 () | SPSK1703M
Flywheel ass’y
2. Then remove the flywheel holder.
1, Remove one screw and then remove two screws. Fig. 8 4243] SPSK1703M
SPSK2003M
For capstan:
1. Remove one screw and then remove two screws.
Then remove the flywheel holder.
. Remove an E ring and then remove the take-up arm ass’y. F
Belts
iz
.8@ REE2000
Pinch roller
arm ass’y together pinch roller arm spring.
1. Remove an E ring and then remove the pinch roller arm ass’y, Fig. 1045) REE1500
Take-up disk Remove a disk screw.
F28457-01
Remove an E ring.
1. Remove an E ring and then remove the take-up arm ass’y. Fig
2. Then remove an E ring.
FF idler ass’y Take-up arm ass‘y
Fig.
8
(8
Pinch roller arm spring @ Pinch roller arm assy
No, 0002 bgt
REE1500
REE2000
REE1500
Fig. 9
Fig. 10

MK-100
Mechanical Adjustments and Repairs
1. Head replacement and adjustment
Clean and demagnetize the head and guide each time the
machine is serviced, If normal fidelity is not obtainable
head replacement is indicated.
Head replacement
1) R/P head
Remove two wires soldered to head.
* Remove a screw and head nut.
Then replace head.
Solder as shown in Fig. 11.
2) Erase head
Remove two wires soldered to head.
Remove a screw and replace head.
Solder as shown in Fig. 11.
Location of heads
The R/P and Erase heads should be positioned as shown in
Fig. 13.
Azimuth adjustment of the head should be done according
to the following instructions.
Screw 7 ' : nad Screw
R/P Head
E. Head Head nut
Fig. 11
Fig. 12
@ Screw
E. Head R/P Head
Fig. 13
Azimuth adjustment
1) Plug a cord into the earphone jack (EAR) and connect a
6 ohm resistor (corresponding to a loudspeaker) in
parallel with the cord.
2) Connect an oscilloscope or electronic voltmeter across
the terminals of the cord.
3) While playing back a test 6.3kHz tape (VTT-651) for
azimuth adjustment, adjust head nut (Fig. 13) so that
the maximum output can be obtained.
4) If no test tape is available, play back a music cassette
and adjust for maximum output and clarity in the high
frequency range.
5) Be sure to lock the head nut () with paint after
adjustment.
2. Pinch roller arm adjustment (Pressure of pinch
roller)
Pressing the pin indicated by the arrow to the play back
mode. Fig. 12
Check to see that the gap between the stopper of head base
and the pinch roller arm should be within 0.3 to 0.7mm.
If it is beyond the limits, adjust it by bending the part @) of
pinch roller arm as shown in Fig. 14.
Head base (stopper) @)
Pinch roller arm
Fig. 14
3. Timing of review action
Move slide control to play (start) position.
Press Review button as far as pin@hits the plastic cam).
Check clearance of ©) for idler pressure, and bend © so
that lid lock plate is kept in place.
Press |
No. 0002

MK-100
4, Motor speed adjustment 7. Fast forwarding torque Fig. 18
1) Plug a cord into the earphone jack (EAR) and connect a Normal torque : 60 gr-cm or more
6 ohm resistor in parallel with the cord. If this is not obtainable,
2) Connect a frequency counter across the terminal of the 1) Clean drive belt, idler and clutch disk tire.
cord, 2) Replace idler ass’y.@
3) While playing back a test 3kHz tape (VTT-656) for 3) Replace clutch disk ass’y. @)
motor speed adjustment, adjust VR on the E governor 4) Replace drive belt. @)
board (see Fig. 16.) so that the frequency counter
indicates within 2,970 to 3,060Hz. 8. Rewinding torque Fig. 18
Normal torque : 40 gr-cm or more
If this is not obtainable,
1) Clean belt, idler and pulley.
2) Replace rewind belt. 6)
3) Replace idler. ©
4) Replace pulley. (7)
Slow Fast
Fig. 16
5. Thrust of Flywheel
The clearance between the top of flywheel shaft and the
flywheel holder should be within 0.1 to 0.3mm.
If the clearance is beyond the limits, adjust the screw for
normal value.
Note: After adjustment, fix the screw with lock adhesive.
Thrust screw
0.1~0.3mm
Fig. 18
Fig. 17
6. Playback torque Fig. 18
Normal torque : 30~40 gr-cm
If this is not obtainable,
1) Clean drive belt, take-up wheel, and clutch disk tire.
2) Replace clutch disk ass’y. (1)
3) Replace take-up wheel. @)
4) Replace drive belt. 3)
No, 0002

| MK-100
Technical Information
1. Stand-by mechanism
When the unit is not loaded with a cassette, the slide contro! knob (3) is immovable since the pin (1) is engaged within the
cam (2). Loading a cassette properly depresses the thrust pin (4) which in turn releases pin (5) permitting the head base (6) to
move forward so the head can make contact with the tape.
However, the tape is not transportable in this mode since the pinch roller and the capstan (9) are not making actual contact
because the S. S. plate (7) is holding back the pinch roller arm (8). This is to say that the stand-by mode is now in effect.
Pushing the slide control knob up towards the PLAY position, will commence running of the tape.
When the cassette is being ejected, the pressing of the eject button pushes backward the head base and pin (4) is pressed
inwards by the spring (10) and the head base automatically returns to its original position. Continuing to press the eject
button in this manner will raise the eject lever (11) and permit the cassette to be withdrawn. Press to lock the REC button
and push the slide control knob up towards the PLAY/REC position to start the tape.
Then the tape will start running for recording.
Pushing the slide control knob down towards the STOP position only stops the tape transport leaving the record button in its
locked position.
This is the same as a conventional pause mode.
In order to release the REC button, push the slide control knob down towards the REW/REC OFF position or press the eject
button. Pressing the REC button during playback, can change the playback mode directly into the recording mode.
Fig. 19
2. Circuit for auto-stop and tape-end warning
This recorder is equipped with a mechanism in which the motor automatically stops and a warning signal becomes audible
from the speaker soon after the tape reaches to its end in any mode. The tape-end is automatically detected by the take-up
disc signalling the tape’s completion.
A reflection plate alternately colored silver and black as shown in illustration is placed on the under surface of the take-up
disc. After the power is turned on, the LED (D15) lights and illuminates this reflecting plate. The photo transistor X11 is
placed to the side of the LED and the impedance across its collector and emitter varies in proportion to the amount of
reflection from the reflecting plate, thus varying its collector voltage. When the reel disc stops, the amount of reflection
ceases to vary and likewise the collector voltage at X11 will become stable.
X12 is a switching transistor and is biased to be turned on by the charging current which flows to C36 through R51 when the
collector voltage at X11 increases in the positive direction from 0. Therefore, while the take-up disc is rotating, X12 con-
tinues
to
be
turned
on
and
off
alternately.
When
the
take-up
disc
ceases
to
rotate,
X12
comes
to
be
turned
off.
On the other hand, after the power is turned on, X14 is biased and turned on through R56 and the motor starts rotating since
the negative pole in the motor governor is earthed. At the same time, C37 is charged through R54 and its voltage across
terminals tends to increase gradually.
—_9_— No. 0002

MK-100 |
However, as mentioned above, since X12 continues to be turned on and off alternately during rotation of the take-up disc,
C37 is immediately discharged through R53 and X12.
When the tape reaches to its end and the take-up disc stops rotating, X12 is already turned off and the voltage between C37
terminals gradually increases. Then, when the voltage sufficiently increases to about 2.7V, X13 is biased and turned on
through
the
zener
diode
D14.
As
a
result,
X13
earthes
X14’s
a
base
and
X14
is
no
longer
biased
but
turned
off,
thereby
halt-
ing
the
motor.
At
this
time,
the
collector
voltage
at
X14
increases
to
correspond
to
the
power
supply
voltage,
switching
on
the oscillator circuit and producing the warning tone from the speaker.
Motor
Warning Tone
OSC. Circuit
Fig. 20
3.
Circuit
for
3-LED’s
level
indicators
and
battery
checker
This
recorder
is
equipped
with
3-LED’s
indicators
that
function
as
level
indicators
during
recording
and
as
a
battery
checker
during
playback.
The recording signal from the main amplifier, during recording, is converted into direct current through R42 and the
quadrupled voltage rectifier circuit composed of C32 — C35 and D10 — D13.
Then the direct current, proportional to this signal, flows through the attenuator composed of R45 — R49 and applied to
transistors X8 — X10, resulting in the lighting of the LEDs according to their specific lighting levels.
In the cases of modes other than stop or recording, a voltage in proportion to the power supply voltage produced through
R41 and R37 is applied to X9 through D8. When the power supply voltage is more than 4.2V (+0.2V), X9 is turned on and
the LED of N (D17) lights.
°
Recording Signai |
0 from Main Amp.
— R4l
Dil2
+B
No. 0002 —~10—