JVC MF-33L User manual

JVC
MODEL
MF-33L/ML
SUN Taller eMUSIC- SYSTEM
No. 7020
May 1978

MF-33L/ML |
Contents
Page
Cautions for Safety Assurance at the Service ....... 2
Specifications... 2... 0.0020 c cee eee eee 3
F@aturres: eco dese ea eilee se wt Be a ee can ee ta 3
Name of External Parts and Internal Parts ......... 4
Disassembly Instruction ........... 000. e eee 5
Record Player Adjustment ..........6..058+00- 6
How to Engage Dial String ........... 0022 eee 6
How to Remove Cassette Door...........200005 7
Removal of Cassette Mechanism. .........002005 7
Check Point After Replacement of Rotation Parts.... 7
Head Replacement and Adjustment ............. 8
Cassette Deck Circuit Board Adjustment.......... 8
Tuner Alignment... 0.0... 0. cee ee ee 10
Block Diagram .... 20... 00. e eee ee renee 12
Circuit Board Diagrams ........ 0.0 cc eee nee eenes 13
Tuner Circuit Board 2.0.0... cece eee ee eee eee 13
Control Amp. Circuit Board ..........2.020000e 14
Cassette Amp. Circuit Board ............0000005 15
NOTE:
Page
Power Amp. Circuit Board ..........0020005 16
Exploded View of Cassette Mechanism ...........- 17
Exploded View of Record Player Mechanism .......- 18
Service Parts List... 0... cc te eee es 19
Circuit Board Parts .. 0... 0.0 cee eee 19
Unit: Parts: 5.0 scans a eeed Aeeie eS ASA SS 21
Record Player Mechanism Parts..............- 22
Cassette Unit 2 occ iteseccete et esiere Hie Se tes 22
Cassette Mechanism Parts. ........6+0205085 23
Characteristics of Transistors. ..........2000005 24
Transistor and IC Lead Identification ............ 24
Terminal Voltages of Transistor &1C ............ 26
Schematic Diagram .......... 002 cee eee ene 27
Tuner Circuit... 1.2... ee ee 27
Control Amplifier... .......00000 eee eee 27
Cassette Circuit... ..... 0002: eee 28
Power Source & Amplifier. .......... 0000005 28
FOR REPAIR OF SPEAKER BAFFLE MODEL BA-33, PLEASE REFER TO THE SERVICE MANUAL
(No. 7021).
Cautions for Safety Assurance at the Service
Cautions for safety assurance at the service
In order to prevent from accidents, like fire or shock
hazard, please keep the following points for the safety.
1. The parts marked with A\ in the list of this manual are
safety assurance parts.
When replacing this kind of parts, make sure to use the
specified one.
2. Although in case of replacing the other kind of parts
than A\ mark, it is recommended to use the parts listed
in this manual to keep appliance safe and reliable.
3. When wire connection is made, solder the connecting
part after winding the wire round the terminal a few
turns in order to prevent easy disconnection.
4. When replacing the parts in the circuit marked in the
schematic diagrams use only the listed parts in this
manual. The marked circuit: ay
5. The symbol mark OOAW-| is showing a fusible resistor,
please use the listed parts.
6. The heat radiating parts (resistor, transistor, etc.) should
be
spaced
enough
from
printed
circuit
board,
plastics
or another electrical parts to be free from its heat.
Some
parts
may
radiate
big
heat
when
transistor
or
circuitry
has
been
damaged.
7.
When
altered
the
working
voltage
or
frequency
of
the
appliance
make
sure
to
specify
it
on
the
appliance
and
its
carton
case.
atin
a
Soldering
No. 7020

Specifications
Cassette deck
Type
Track System
Bias & Erase
Frequency
Response
Wow and Flutter
Signal to Noise
Ratio
Amplifier
Type
Music Power
Tuner
Type
Tuning Range
Antenna
Sensitivity for FM
FM Stereo
Separation
Features
: FM
: Stereo Cassette Deck with Auto-Stop
: 4-Track, 2-Channel Stereo
:-AC Bias & AC Erase
: 30—13,000Hz (Normal Tape)
30—15,000Hz (Chrome Tape)
: 0.15% (WRMS)
: Better than 50dB (at Peak Level)
without Dolby noise reduction. The
S/N ratio is improved by 5dB at 1kHz
and 10dB above 5kHz with Dolby
noise reduction on.
: IC Power Amplifier with Bass and
Treble Controls 15W RMS per channel
at 8 ohms
: 40W
: 4-Band (FM/MW/SW/LW) Stereo
Tuner
88—108MHz
MW 520—1600kHz
SW 6—18MHz
LW 150—350kHz
: FM 300 ohms balanced
:4yuV
: 40dB (1kHz)
15 WATTS RMS PER CHANNEL POWER OUTPUT
4-BAND (FM/MW/SW/LW) RECEIVER
DOLBY NOISE REDUCTION SYSTEM
AUTO-STOP STEREO CASSETTE DECK
AUTO-RETURN BELT-DRIVE TURNTABLE
SPEAKER SELECTOR SWITCH (A, B, A + B)
MF-33L/ML
Turntable
Type : Belt-Drive Auto-Return
Speeds : 33-1/3, 45rpm
Platter : 28cm (11)
Motor : FG Servo Motor
Cartridge : Moving Magnet
Stylus : Diamond
General
: 110/120/220/240V, 50/60Hz or
240V, 50/60Hz
Power Sources
JVC recommends a JVC 2-way Ajir-Suspension Speaker
System with Passive Radiator (Drone Cone) Model
BA-33/33M for matching performance and appearance of
your MF-33L/ML.
No. 7020

MF-33L/ML
Name of External Parts and Internal Parts
219 435 6
23 24
22
Fig. 2
Parts Name
Parts No.
Side Panel Ass’y
Refer to Parts List Page 21
17 18 16 151214 13 10 11 9 Dust Cover Ass’y ”
Hinge Ass‘y Y¥30120-003
Bottom Case *¥10082-001
Fig. 1 Speaker Terminals *QMB0484-002
Antenna Terminals *QMB0484-001
DIN Socket Ass’y *Y00122-001
Voltage Selector
QSR0074-001
Parts Name Parts Name
1 Front Panel Ass‘y Refer to Parts List Page 21 Spring (Knob) Y40462-001
2 Cassette Door Holder Ass’y ” Microphone Jacks *Y00127-001
3 | Tape Counter TGW291324-0A Control Knobs *¥ 4056 1-001
4 | Tape Select Switch *QSS4201-051(EQ) Speaker Select Knobs Y40428-001
QSS2201-003(BIAS) Push Shaft Y30264-001
5 Dolby NR Switch QSS4201-051 Headphone Jack QMS6302-015
6 Level Meter *Y00119-001 Cassette Grille Ass’y Refer to Parts List Page 21
Lamp (Meter) QLP4101-004B Cassette Push Buttons ”
7 | Dial Scale *¥20075-001 Beat Cut Switch *QSS2301-005
8 | Dial Needle *Y40567-001 Power Switch Knob Ass’y *¥40490-002
Lamp (Needle) Y00124-400 Cabinet Case Y10063-001
9 | Tuning Knob *Y 40560-001 Player Mechanism Refer to Parts List Page 22
10 | Push Switch Knobs *Y40562-001 Indicator TLR114 |
“a a
—
Parts Name Parts No.
Tuning Shaft Ass’y *Y¥KA40065-002
Dial Drum QZD1115-001
Spring (Drum) Y40276-002
No. 7020
Tuner Circuit Board Ass'y
Contro! Circuit Board Ass’y
Cassette Mechanism Ass’y
Cassette C. Board Ass’y
Power Switch C.B. Ass’y
Power Amp. C.B. Ass‘’y
Antenna C.B. Ass’y
Power Transformer
Power Cord
Fuse
Refer to Parts List Page 19
Refer to Parts List Page 20
Refer to Parts List Page 23
Refer to Parts List Page 19
Refer to Parts List Page 20
"
”
Refer to Parts List Page 21
——

Disassembly Instruction
Step 1.
Record Player
Remove 2 screws with motor board floated and disconnect
2 plugs from underside of player board.
U
Fig. 4
Step 3. "
Cabinet Case (Step 2.)
Remove 4 screws.
Fig. 6
Step 5.
Cassette Mechanism
@ Remove cassette door holder. (Refer to page 7)
© Remove 4 screws in Fig. 8 and remove 1 screw of arrow
mark Jin Fig. 7.
Front Panel
MF-33L/ML
Step 2.
Cabinet Case (Step 1.)
Remove 1 screw.
Fig.
Step 4. ig. 8
Cabinet Case (Step 3.)
Remove both sides panels and remove 2 screws of arrow
mark 4 on both sides.
Fig.7
Step 6.
Circuit Boards
Tuner Remove 5 screws.
Control Take off the control knobs and remove 6
screws.
Power Remove screws of the speaker terminals
(A & B) and remove 6 screws.
Fig. 9
No. 7020

MF-33L/ML |
Record Player Adjustment
Confirmation of Normal Operation of Auto return
Mechanism
When you bring pickup head part to the position of boss
(A) while keeping the Lower Trip Pawl pushed inward
(Arrow B) by hand, if pickup does not move forward,
operation of auto return mechanism is normal. (Fig. 10)
Adjustment Screw
Fig. 11
Speed adjustment of turntable
Adjust two semi-fixed resistor on the motor control circuit
board for each speed.
45 rpm : (A)
33 rpm : (B) in Fig. 12
Fig. 10
Lead-out adjustment
After replacing cartridge or lead-out mechanism parts, make
sure of normal operation of lead-out.
® Confirmation & Adjustment.
1) Lead-out should be made when playing JVC test
record RG-652 (pitch 3mm).
1f not, turn the adjusting screw (Fig. 11) counter-
clockwise.
2) Lead-out should not be made when playing the
record RG-653 (Reverse side of RG-652).
If it is made, turn the adjusting screw clockwise.
Repeat above 1) & 2), and fix the adjusting screw at the
correct position for normal lead-out.
Fig. 12
How to Engage Dial String
1. Set the variable capacitor on maximum.
2. String dial cord in numerical order as shown in the arrow marks.
3. Overall length of cord is 655cm.
Fig. 13
No. 7020

How to Remove
Cassette Door Holder
_
. Open the door by depressing “EJECT” knob.
2. Take off the brake shaft arm connected with the door at
left-hand of the cassette compartment.
3. Depress the opened door toward you so as to open it
further.
Notice: Check Point of Door Trouble
If opening or closing the door is not smooth,
check the following points.
1. Whether the small hole of brake pipe (inside) is choking
with something like dust.
2. Whether grease on brake shaft is running out.
3. Whether “O” ring of the shaft is deforming.
MF-33L/ML
Removal of Cassette
Mechanism
For
removing
cassette
mechanism
parts,
do
it
in
the
fol-
lowing
way
referring
to
“Exploded
View
of
Cassette
Mechanism” on page
(1)
Regarding
the
parts
to
which
the
belt
is
fitted,
take
off
the
belt
first.
(2)
Regarding
the
parts
to
which
the
spring
is
hooked
up,
take
off
the
spring
first.
(3)
Regarding
the
other
major
parts,
remove
screw
or
“E"'
ring
which
fixes
the
parts
to
be
removed.
CAUTION:
1.
As
for
rotation
parts
such
as
reel
disk
etc.,
pull
it
out
vertically from the shaft.
2.
Be
careful
not
to
soi!
belt
or
rubber
Parts
in
oil
etc.
Check Point After Replacement of Rotation Parts
1. Pinch Roller Pressure
@ It must be within 380~580 g/cm.
@ The roller continues to rotate after being rotated by
the finger.
@ The roller surface contacting the capstan must be
vertical,
2. Flywheel
@ A little thrust clearance exists between flywheel! shaft
bearing and special washer.
@ The capstan is clean, correctly centered, and provides
quiet rotation.
3. Take-up Torque
It must be within 40~70 g/cm.
If torque is out of the specified range, take the following
measures.
1) Clean take-up belt, surfaces of idler and reel-disc.
2)
Change
the
position
of
the
spring
holder
in
the
clutch
pulley.
(Refer
to
Fig.
14)
3) Nevertheless, if the standard torque is not obtained,
replace take-up clutch arm ass’y.
4. Fast Forward and Rewind Torque
The standard torque should be over 60 g/cm.
If the torque is less than the specified range, take the
following measures.
1) Clean take-up belt, rubber part of reel-disc, and all
parts to which the belt gets in contact.
2) Change the position of the spring holder in the F.F.
idler. (Refer to Fig. 14)
3) Adjust or replace the springs concerned.
4) In case the rubber parts was worn out, replace to new
one.
F.F. idler
Clutch pulley
Fig. 14
Note: To adjust the spring holder, raise it up with a
screwdriver and shift to higher position by turning.
The torque is the higher the stronger.
No. 7020

MF-33L/ML |
Head Replacement and Adjustment
If either of Recording/PB head and Erase head shows low performance caused by wear, broken wire or excessive magnetiza-
tion, it should be replaced. They can be removed by loosening screws with following procedure. After replacement, adjust
azimuth of head.
Azimuth Adjustment
Step
1.
2.
3.
Connect INPUT jack of V.T.V.M. to LINE OUT of
REC/PB socket.
Play back the standard tape (Full Track or JVC Test
Tape VTT658 10kHz) for azimuth (angle adjustment).
Adjust screw Q) so that indication of V.T.V.M. will
become max.
When standard tape for azimuth adjustment is not
available, play a music cassette tape.
Make treble sound optimum with turning the screw
. After this adjustment, the screw @® should be locked
with a bond.
If necessary, adjust playback level, recording bias current,
and trap etc.
Yad
Erase Head
©
© Bae
=
eS
@ ® @ if
Fig. 15
Cassette Deck Circuit Board Adjustment
Item of Adjustment
arWN—
. Dolby Noise Reduction Level
. Level meter
. Playback Gain
. Recording bias current
. Recording current
Equipment and measuring instruments to be used
for adjustment
1.
On aah WN
No. 7020
VTVM (measuring AC in milivolts)
. Oscilloscope
. Oscillator
. Attenuator
. Frequency counter
. Standard tape VTT-664 (1kHz 16mM/mm)
. C-60 Normal sub-standard tape
- 100Q Resistor
R/P
Head wo
Frequency
counter
1002
AC milivoltmeter
Fig. 16

—_
. DOLBY N.R. Level
1. Set SOURCE SELECT switch to “AUX”.
2. Set DOLBY N.R. switch to “OFF”.
3. Set the deck in recording mode.
4. Apply 1kHz signal of proper level (0.5V_ ap-
proximately) to “AUX” input terminal.
. Adjust the front REC VOLUME so that the signal
level will be -25 dBm at the terminals of VR401
(L-ch) and VR402 (R-ch) respectively. (Refer to Fig.
17)
6. Finally adjust VR401 and 402 so that the level will
be -2.5 dBm at the Dolby T.P. (L) and (R).
ol
2. Adjustment of Level Meter
After adjustment of Dolby Noise Reduction Level
was completed, adjust the VR303 (L) & VR304 (R) so
that the level meter indicates Cal (+3VU). (Refer to Fig.
17)
3. Playback level
1. Set SOURCE SELECT switch to “TAPE”.
2. Set EQUALIZER switch to “NORMAL”,
3. Set DOLBY N.R switch to “OFF”.
4. Play the reference tape VTT-664, (1kHz), and adjust
VR301 (L-ch) and VR302 (R-ch) so that the level
meter will indicate OVU.
4. Adjustment of Recording bias and frequency
1. Connect a resistor 10082 to the earth side terminal
of R/P head in recording state, and connect AC
milivoltmeter to the both terminals of the resistor.
(Refer to Fig. 16)
2. While changing the bias switch, adjust so that the
specified current will be obtained. The adjustment
should be made from “CHROME”.
.
Bias
Lo
ow
Place
to
be
adjusted
Current
VR307
(L-ch)
550uA
CHROME
|
vR308
(R-ch)
(55mV/1002)
NORMAL
|
VR
309
(L,R-ch)
400uA
(40mV/1002)
3. Regarding bias frequency, adjust T301 so that 57kHz
will be obtained when the front BEAT CUT Switch is
set to 1.
MF-33L/ML
es 0)
nf oa
VR402 (s)
vraoi@)
Fig. 17
5. Adjustment of Recording signal current
1. For this adjustment, it is necessary that the swing
angle of the level meter and playback sensitivity are
correctly adjusted previously.
2. Set the equalizer switch and bias switch to
“NORMAL”,
3. In recording state, apply 1kHz signal of proper level
(0.5V approximately) to “AUX” input terminal, and
adjust the front Recording volume so that the level
meter will indicate OVU.
4. In this state, repeating the recording and playback,
adjust VR305 (L-ch) and VR306 (R-ch) until the
level meter indicates OVU.
Tape speed
Standard speed: 3,000Hz +2% (at playing a 3,000Hz test
tape)
If not as specified, insert your driver in hole on the motor
upside and adjust a semi-VR for speed control in the motor
case.
(Fig. 17 * )
No. 7020

MF-33L/ML |
Tuner Alignment
AM IF & RF ALIGNMENT x ~10kHz 0 10kHz y,
1 te x
@
IF
Alignment
mas
Equipment
required
:
455kHz
Sweep
Generator
with
Oscilloscope
}
Input
terminal
:
Ain
Fig.
20
‘
Output terminal : Bin Fig. 20
@ RF Alignment
Equipment required : Standard Signal Generator
Modulation 1000Hz, 30%
Input terminal : Loop Antenna for LW and MW
AM
antenna
terminal
for
SW
Fig.
18
Output terminal : Speaker terminal
Alignment point Set V. Capacitor to
Po4 | mw 455kHz CF 103, T103 | Center
(IF)
Adjust CF 103, T103 Fig. 18
Repeat the step 3 & 4 to get the best point of adjustment.
6MHz L111 6MHz
Repeat the step 6 & 7 to get the best point of sensitivity.
510kHz Maximum
1650kHz Minimum
Repeat the step 9 & 10 to get the best point of adjustment.
1400kHz C184 1400kHz
Repeat the step 12 & 13 to get the best point of sensitivity.
360kHz C199
Repeat the step 15 & 16 to get the best point of adjustment.
160kHz L112 (LW Bar ANT.) 160kHz
350kHz C181 350kHz
Repeat the step 18 & 19 to get the best point of sensitivity.
aa
=
=<
NOTE: When bar antenna coil of MW or LW is adjusted, check the tracking error for each band, because two coils
slightly interfere each other.
Always use an insulated screw driver for adjustment.
Fig. 19
No. 7020 —10-
nen,