JVC PC-70L User manual

JVC
SERVICE MANUAL
Contents
Page Page
Safety Precautions .......... Jasbeqnntscechqeilnmbanasengaeinoeate cs 2 Standard Schematic Diagram of PC-7O0LD
FGAtUleS fiasco ees sins tap nccicy nea ee 3 (Amplifier Circuit) .......0...cccccccccceceeseeeeues baliiemectinuic’ 22
Specifications
:
3
P.C.
Board
Parts
and
Parts
List
(SEA
P.C.
Board)
.........
23
Name of Controls and Connection Terminals ...... ite dvedy 4 SEA P.C. Board Parts List .......00...0c.ccccacsecseeceeueeeees
Attaching
and
Detaching
the
Speaker
...................0000
6
Tuner
P.C.
Board
Parts
.............ccccecccusescussceeueseeeenses
Location
of
Main
Parts
...
Tuner
P.C.
Board
Parts
List
Removal of Main Parts ................0.ccccccecceeceeeseuseaeenes Phono P.C. Board Parts ....
Mechanism
Parts
............0ccccccsececcecenccecsueccaeeeneeeeees
Phono
P.C.
Board
Parts
List
How
to
Engage
Dial
Cord
...........0.0.ccccececcceeeeeeeeeeesees
Power/LED
P.C.
Board
Parts
...0........c0cccccccececeseeerneees
Main
Adjustment
.....................005
Power/LED
P.C.
Board
Parts
List
Mechanical
Adjustment
Power
Amp
P.C.
Board
Parts
List
.........
Cassette
Amplifier
Adjustment
............00..00cccce
evens
13
Enclosure
Assembly
and
Electrical
Parts
Tuner
Alignment
.........0.06...ccecceeneeceseneeereneneeeeeeeees
Enclosure
Assembly
and
Electrical
Parts
List
............
29
Wiring
Connections
.
Mechanical
Component
Parts
List
..........0...c..c0ceeeeee
Block
Diagram
Mechanical
Component
Parts
Integrated
Circuit
.........0....ccccecesccccaveeeeteeaeeeenes
sage
Exploded
View
and
Parts
List
for
Speaker
Standard
Schematic
Diagram of
PC-7OL/LB
Speaker
System
Assembly
Parts
List
......0.....0....0605-
(Tuner Circuit) ......cccccccceeccesceevecesecedsccaeeesecesieeeees 20 Packing oi icss.esccsccsbcssscusvsuene Jin tievactasSeectraulamiecrestess se 37
Standard
Schematic
Diagram
of
PC-70LD
Packing
and
Packing
Parts
List
(Tuner
Circuit)
........00cc.ccccccccsecesecsccuuesseueusnes
insertion
ACCOSSOTIES
20.0...
c
cc
cecececceccueucecocuseeecsecaraeuens
Standard
Schematic
Diagram
of
PC-7OL/LB
(Amplifier Circuit) ......0...0..00..cccccccuceecccneeusecusenesens 21
No. 1543
January 1984

PC-70 L/LB/LD/LS
2
Safety Precautions
1. The design of this product contains special hardware. 5. Leakage current check
Many circuits and components specially for safety
purposes.
For continued protection, no changes should be made to
the original design unless authorized in writing by the
manufacturer. Replacement parts must be identical to
those used in the original circuits. Service should be per-
formed by qualified personnel only.
2. Alterations of the design or circuitry of the product
should not be made. Any design alterations or additions
will void the manufacturer’s warranty and will further
relieve the manufacturer of responsibility for personal in-
jury or property damage resulting therefrom.
3. Many electrical and mechanical parts in the product
have special safety-related characteristics. These
characteristics are often not evident from visual inspec-
tion nor can the protection afforded by them necessarily
be obtained by using replacement components rated for
higher voltage, wattage, etc. Replacement parts which
have these special safety characteristics are identified in
the parts list of Service manual. Electrical components
having such features are identified by ( A\ ) on the
schematics and parts list in Service manual. The use of a
substitute replacement which does not have the same
safety characteristics as the recommended replacement
part shown in the parts list in Service manual may create
shock, fire, or other hazards.
4. The leads in the products are routed and dressed with
ties, clamps, tubings, barriers and/or the like to be
separated from live parts, high temperature part, mov-
ing parts and/or sharp edges for the prevention of elec-
tric shock and fire hazard.
When service is required, the original lead routing and
dress should be observed, and they should be confirmed
to be returned to normal, after re-assembling.
DC motor
(Safety for electrical shock hazard)
After re-assembling the product, always perform an
isolation check on the exposed metal parts of the Pro-
ducts (antenna terminals, knobs, metal cabinet, screw
heads, earphone jack, control shafts, etc.) to be sure the
product is safe to operate without danger of electrical
shock.
Do not use a line isolation transformer during this check.
e Plug the AC line cord directly into the AC outlet. Us-
ing a ‘‘Leakage Current Tester’’, measure the leakage
current from each exposed metal part of the cabinet,
particularly any exposed metal part having a return
path to the chassis, to a known good earth ground
(water pipe, etc.). Any leakage current must not ex-
ceed 0.5 mA AC (r.m.s.).
e Alternate check method
Plug the AC line cord directly into the AC outlet. Use
an AC voltmeter having 1,000 ohms per volt or more
sensitivity in the following manner. Connect a
1500 2 10 W resistor paralleled by a 0.15 wF AC-
type capacitor between an exposed metal part and a
known good earth ground (water pipe, etc.).
Measure the AC voltage across the resistor with the
AC voltmeter.
Move the resistor connection to each exposed metal
part, particularly any exposed metal part having a
return path to the chassis, and measure the AC
voltage across the resistor. Now, reverse the plug in
the AC outlet and repeat each measurement. Any
voltage measured must not exceed 0.75 V AC
(r.m.s).
This corresponds to 0.5 mA AC (r.m.s).
AC VOLTMETER
(Having 1000 ohms/volt,
or more sensitivity.)
ee
ee
ot
4
0.15
pF
AC-TYPE
a
a
aor
cee
4
$a
hee
Place
this
probe
150092
10W
on
each
exposed
lo
metal
part.
Good
Earth
Ground
|
DC Jack
AC Jack
V. Select switch
Power transformer
Fuse
(No. 1543)

Features
1. Fashionable mini stereo component system
Fashionable P-Compo system consisting of 3 units
with attachable/detachable speakers.
2. Total output of 10 W (5 W+5 W) max. (3.2 ohms)
Music power of 12 W (6 W+6 W) (3.2 ohms)
“U-Turn’’ Auto-reverse deck for recording/playback
with soft-touch machanism
PC-70 L/LB/LD/LS
Timer start mechanism
Two-position tape slect switch (METAL/NORMAL)}
5-LED peak indicators
5-elements S.E.A. Graphic equalizer
PHONE/LINE IN jack provided for the connection f
turntable or tape deck.
3-way power supply (AC, batteries, and car bat-
Metal tape compatibility
One-touch recording facility
Built-in microphone
single music scan facility for both directions.
‘‘Under license of Staar S.A, Brussels, Belgium’’.
Specifications
Speakers
Frequency ranges
Antennas
Track system
Motors
Heads
Frequency response
Wow & flutter
S/N ratio
Rewind time
Fast forward time
Power output
S.E.A.
characteristics
: 10 cm (4”) (3.2 2)x 2
:FM 88—108 MHz
MW 540-1600 kHz
LW 150—350 kHz
SW 6—18 MHz
: Telescopic antenna for FM & SW
Ferrite core antenna for MW & LW
: 4-track 2-channel stereo
: Electronic governor DC motor for
capstan & reel
: METAPERM head (for recording/
playback)/2-Gap Ferrite head (for
erasure) combination head
: 6O— 14,000 Hz (with metal tape)
60—13,000 Hz (with normal tape)
: 0.08% (WRMS)
0.18% (DIN 45500)
: 45 dB
: Approx. 110 sec. (C-60 cassette)
: Approx. 110 sec. (C-60 cassette)
: Max. 10 W (5 W + 5 W)
Peak music power of 12 W
(6 W + 6 W)
S.E.A. center frequencies:
: 63 Hz/250 Hz/1kHz/4 kHz/16 kHz
S.E.A. control range: + 12 dB
teries)
3. Acoustic suspension speakers
¢ 10-cm full range speaker x 2
¢ Speaker connection cords with mini-plug
Input jacks
Output jacks
Power supply
Power consumption :
: 502(W) x 149(H) x 184(D) mm
Dimensions
Weight
: Mic x 2 (0.78 (—62 dBV))
Matching impedance: 200 2—2 kQ
2, selectable between PHONO
(0.8 mV/47 kQ) and LINE IN
(100 mV/47 kQ)
: Speaker x 2 (matching impedance
3.2—8 Q)
Headphones (matching impedance
8—32 Q)
:DC 12 V (8 “R14” cells)
Car battery through a car battery
adapter AC 240/220/110 V,
50/60 Hz
16 Watt
(19-7/8”" x 5-7/8” x 7-1/4”)
including knobs
: Approx. 4.4 kg (9.7 Ibs)
(without batteries)
Approx. 4.9 kg (10.8 Ibs)
(with batteries)
Design and specifications are subject to change without
notice for improvement.
(No. 1543)
3

PC-70 L/LB/LD/LS |
Name of Controls and Connection Terminals
=
Oe
Hh
oe
ey
. Speakers (Left, Right)
2. Indicators
OMAN OaF
10.
11.
4 (No. 1543)
¢ DIRECTION
¢ POWER/BATT
e LEVEL
¢ TUNE
¢ FM STEREO
. SOURCE switch
( — ) PHONO/LINE
( m ) RADIO
. TAPE MONITOR switch
. EXT MICROPHONE jacks
. FINE TUNING knob for SW reception
. Tape COUNTER/reset button
. Dial scale
. MODE switch
( m ) STEREO
( = ) MONO
BAND switches (FM/SW/MW/LW)
Built-in microphone (Monaural)
Fig. 1
12. TUNING knob
13. VOLUME controle
14. Cassette holder
15. Cassette operation buttons
* (Stop/Eject) button
«<<
(Rewind) button
© (Record) button
<« PLAY » button
pe (Fast Forward) button
ft! Pause button
16. REVERSE MODE switch
>)
>
: Continuous play
: Full recording or playback
: Single recording or playback
17. DIRECTION switch
18. TAPE switch
19. POWER switch
20. Headphones jack (PHONES) (3.5 mm dia. stereo
miniplug)
21. SEA Graphic Equalizer controls

PC-70 L/LB/LD/LS
Ba
vod
ret
27 28 29 [phone]
Fig. 2-1
22. Telescopic antenna for FM or SW reception 29. VOLTAGE SLECTOR (240/220/110 V)
23. Battery compartment cover 30. AC IN jack
24. GND (ground) terminal 31.12 V DC IN jack ( e- )
25. PHONO/LINE IN jacks 32. BEAT CUT switch
26. PHONO/LINE IN select switch 33. Speaker cord with plug (Left)
27. Speaker lock lever (Right) 34. Speaker lock lever (Left)
28. Speaker cord with plug (Right)
PC-70LD/LS only
Din Jack
ae 2s
i E
L wae a"
voUrice
sezcton | if
sf (R) ~ ACN
IN320
(No. 1543) 5

PC-70 L/LB/LD/LS
Attaching and Detaching the Speaker
When using the speaker attached to the receiver
When using the speakers attached to the main unit. When using the speakers detached from the main unit.
1. Hold with the bottom of the speaker against the top of 1. Set the speaker lock lever to RELEASE.
the main unit and press down the speaker to attach it. 2. Lift the speaker to detach from the main unit.
Note: Be sure to set the speaker lock lever to e A better stereo effect can be obtained when the
RELEASE. speakers are placed an appropriate distance from the
main unit.
e The right speaker is detached in the same way.
Speaker slot
~= RELEASE
Press the speaker down
with the speaker and
main unit aligned.
Speaker cord connections
As illustrated, connect the speaker cord plug into the jack
and fix it securely.
2. Set the speaker lock lever to LOCK.
¢ The right speaker is attached in the same way.
6 (No. 1543)

PC-70 L/LB/LD/LS
Location of Main Parts
Front
view
Tape
monitor
switch
Mode
switch
Source
switch
i i
a
Mic
jack
Fine
tuning
x
Band
selector
a
=
Ss
is
«
is
q —— ies = Pointer
Counter
1 ee Tuning knob
Volume
Phones jack
Mechanism Ass’y Power switch
Tape selector
Fig. 7
Rear view
Ferrite core antenna LED P.C. Board Ass’y
Pointer
Tuner P.C. Board
Ass’y
<> DC motor
Phono. P.C. Board
Ass'y
PHONO/LINE
el) Jack
BEAT CUT
switch
DC Jack
SEA P.C. Board
Ass‘y Fuse Power transformer AC Jack SP Jack
Power P.C. Board SP Jack V. Select switch
Ass'y
Fig. 8
(No. 1543) 7

PC-70 L/LB/LD/LS
Removal of Main Parts
Fuse replacement
1. Remove the rear panel to replace the fuse.
Rod antenna replacement
1. Remove the screw marked ‘‘ANT SCREW” and replace
the rod antenna.
Removal of rear panel
1. Remove the eight screws (1) ~ GB) from the bottom
and rear panels.
2. Remove the antenna and battery wires.
a ~ Soy? 7 : i
’ As, > aa
ie SNS Sahn
RN f on
D- Qoeprnae va
x2
7 seSF3065N«5 &
Fig. 9
Removal of bottom panel
1. Remove the six screws (4) ~ 6) ; wy
(Remove the rear panel or loosen the screws @) ~
@) before this.)
ans
oe
‘ ?
© nS
Removal of top panel
1. Remove the bottom panel.
2. Pull the fine tuning knob to remove it.
8 (No. 1543)

Removal of front panel
1.
Remove
the
two
screws
@)
and
(8).
2.
Remove
the
lever
cap
and
volume
control
and
then
open
the cassette holder to remove it.
Note:
When
reassembling,
set
the
reverse
mode
switch
to [==] or{c).
Removal of tuner board
1. Remove the two screws Q) and (0) ;
2. Remove the connector wires 4P and 6P, then remove
the connectors from CN101 of the amplifier board.
Note: When reassembling the unit, turn the dial drums
and variable capacitors fully clockwise.
Removal of power transformer
1. Remove the screw
2. Remove the solder from the wires.
Removal of mechanism Ass’y
1. Remove the counter belt.
2. Remove the four screws
Removal of phono board
1. Remove the two screws a3) ‘
2. Remove the connector wires from the amplifier board.
Removal of LED board
1. Remove two screws a4 :
Removal of counter
1. Pull in the direction of the arrow.
PC-70 L/LB/LD/LS
loner AmpiSP
lager Amptsk
ie
= VS
(11)
0PsP30062%2
Ay
Fig. 13
Aa oy
(1g) S8SF3008 x2
SDST3006Z x 2
13}
42) SBSF30122Z x4
oS
Fig. 14
(No. 1543)
9

PC-70 L/LB/LD/LS
Removal of chassis base
1. Remove the two screws (15) :
Removal of SEA board
1. Remove the two screws and (1
2. Remove the connector from CN104 of the amplifier
board.
Mechanism Parts
1. Flywheel and belt
1)
Remove
two
screws
(B)
fastening
the
F.R.
bracket,
and remove the main belt.
2) Pull out the flywheel with the reel drive belt.
2. Reel assembly unit
Remove
4
screws
(A)
fastening
the
reel
ass’y
unit.
3. Motor
1)
Remove
two
screws
fastening
the
motor
from
the
F.R. bracket.
2) Pull out the motor pulley from the motor shaft.
4. Reel feather
Pull out the reel feather from the shaft.
10 (No. 1543)
4. (15) SBSF 30122 «2
Fig. 15
17) sBsF 30122
46: LPsP 30087