JVC PC-Y777 B User manual

PC-Y777 B/E/G =
SERVICE
MANUAL
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Contents
Page Page
[1] Safety Precautions ...............ccccceenee eee eec teen een eeeee 2 Standard Schematic Diagram ......................0600 19
Safety Precautions about PC-Y777 ...............:45 3 [11] Wiring Connections ............:ccceeeeeeesesseeeeneenens 21
Features .........ecceseceecnesecseeeeeseeceesentetenesereceeoees 4 Location of P.C. Board and Parts List ................ 22
[4] Specifications 2.0.0.0... ccc cece ce cece cence tent en ee eeeeeees 4 [13] Exploded View of Mechanism Component
[5] Name of Controls and Their Functions ..............- 5 and Parts List 2.2.0.0... cece eee nese eee ee eee rere eeeeenene 28
[6] Location of Main Parts ...........cccceeseeeseeneeetees 7 Exploded View of Enclosure Assembly
Removal of Main Parts ................ccececeeeeee eee eens 10 and: Parts List o.cci0iccctscadewiiv ected qetasavae seeders saci 30
Main Adjustments .................cccceeeeeeeceeeeeeeeeeeees 12 [15] Packing Illustration and Packing Parts List ......... 34
[9] Block Diagram ..............c cece ccc cc nee ee eee e neces eeeeee 18
No. 1802
July 1990

PC-Y777 B/E/G |
2
~|1| Safety Precautions
1. The design of this product contains special hardware and many circuits and components specially for safety
purposes. For continued protection, no changes should be made to the original design uniess authorized in writing
by the manufacturer. Replacement parts must be identical to those used in the original circuits. Service should
be performed by qualified personnel only.
2. Alterations of the design or circuitry of the product should not be made. Any design alterations of the product
should not be made. Any design alterations or additions will void the manufacturer’s warranty and will further
relieve the manufacturer or responsibility for personal injury 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 inspection 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 schematic diagram and Parts List in Service Manual. The use
of a substitute replacement which does not have the same safety characteristics as the recommended replace-
ment 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 the like to be separated
from live parts, high temperature parts, moving parts and/or sharp edges for the prevention of electric shock
and fire hazard.
When service is required, the original lead routing and dress should be observed, and it should be confirmed
that they have been returned to normal, after re-assembling.
5. Leakage current check (Electrical shock hazard testing)
After re-assembling the product, always perform an isolation check on the exposed metal parts of the product
(antenna terminals, knobs, metal cabinet, screw heads, headphone jack, control shafts, etc.) to be sure the pro-
duct is safe to operate without danger of electrical shock.
Do not use a line isolation transformer during this check.
* Plug the AC line cord directly into the AC outlet. Using 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. Any leakage current must not exceed 0.5 mA AC (r.m.s.).
® 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 1,500 2 10 W resistor paralleled by a 0.15 uF AC-type capacitor
between an exposed metal part and a known good earth ground.
Measure the AC voltage across the resistor with the AC ET Were ons cea
voltmeter. or more sensitivity.)
Move the resistor connection to each exposed metal o Sl
part, particularly any exposed metal part having a return
. 0.15 pF AC TYPE
path to the chassis, and measure the AC voltage across
the resistor. Now, reverse the plug in the AC outlet and ‘ Blake thiscorebe
repeat each measurement. Any voltage measured must on each etpcaad
not exceed 0.75 V AC (r.m.s.).
1500 2 10 W metal part.
This corresponds to 0.5 mA AC (r.m.s.).
Good earth ground
—Warning
. This equipment has been designed and manufactured to meet international safety standards.
. It is the legal responsibility of the repairer to ensure that these safety standards are mainteined.
. Repairs must be made in accordance with the relevant safety standards.
. It is essential that safety critical components are replaced by approved parts.
. If mains voltage selector is provided, check setting for local voltage.
oh WON =
(No. 1802)

| PC-Y777 B/E/G
Safety
Precautions
about
PC-Y777
PRECAUTIONS
Prevention of damage to the set
1. Do not leave this unit in direct sunlight or in extremely
hot (about 40°C (104°F)) or humid places or in closed
automobiles in the sun.
2. Exhausted batteries in the unit may cause damage due to
corrosion.
When the unit is not used for more than 2 weeks, remove
the batteries.
3. Never use benzine or thinner for cleaning as these will
damage the cabinet.
4. Place the unit as far away from the TV as possible.
Prevention of electric shock and fire hazards
1. Even when the POWER switch is set to STANDBY, a
very small current will flow. To save power and for
safety when not using the unit for an extended period
of time, disconnect the power cord from the household
AC outlet.
2. Do not handle the power cord with wet hands.
3. When unplugging the power cord, always grasp and pull
the plug, not the power cord.
CAUTION:
|
TO
REDUCE
THE
RISK
OF
ELECTRIC
SHOCK,
4,
Consult
your
nearest
dealer
when
damage,
disconnection
|
DO
NOT
REMOVE
COVER
(OR
BACK).
or
contact
failure
is
found
with
the
cord.
NO
USER-SERVICEABLE
PARTS
INSIDE.
REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
The lightning flash with arrowhead symbo!, The exclamation point within an equilateral
within
an
equilateral
triangle,
is
intended
to
triangle
is
intended
to
alert
the
user
to
the
alert the user to the presence of uninsulated Presence of important operating and main-
“dangerous
voltage”
within
the
product's
tenance
(servicing)
instructions
in
the
litera-
enclosuré that may be of sufficient magni- ture accompanying the appliance.
tude to constitute a risk of electric shock to
persons.
B
Important
management
points
regarding
safety
A
@
(version
‘
only
z
(Items
Demanding
Special
Safety
Precautions)
gaat
:
1. Make sure that the soldering round does not protrude in
order to maintain a gap between the primary circuit of
the circuit board and the pattern adjoining the primary
circuit.
2. Confirm that the power transistor is provided with the
parts number ‘’VTP57P2-12C/VTP57P2-12CBS"’, and
to prevent the pattern from coming off, confirm that the
fixation screw for the circuit board is not loose.
3. Confirm that the AC socket is provided with the number
“HSC 1466" and that the pattern is properly fixed.
4, Check that clamping has been properly performed to pre-
vent contact with heated parts.
5. As D999, the heat sink IC801, 802,911, R751, R761,
R723, R814, R815, R28, Q914 and 0916 are heated
parts, make sure that they do not come in contact with
the wire and the E. cap.
6. Confirm that fuses F998 and F997 ‘’T4A” “’250” are
properly
maintained,
and
that
the
volume
indication
seal
‘
DTS
Board
ae co
aed
Tuo d
T4A/125"
is
attached
next
to
the
fuse.
‘aprenne
oe
aes
Ti Ts
7.
In
order
to
prevent
the tuner
wire
from contacting
the
Wire
primary fuse, check that the wire is inseted into the rib
and that it is fastened with bond.
8. Make sure that all support parts are bonded and fixed
with spacers.
Amp Board
(No. 1802) 3

PC-Y777 B/E/G |
4
Features
1. MW/LW/FM-stereo PLL synthesizer tuner.
@ 20-station preset tuning (FM-10, MW-5, LW-5).
@ Seek/manual tuning.
2. Double-cassette mechanism (Deck A for recording and
playback, Deck B for playback).
¢ Dolby*B Noise Reduction system.
Metal and CrO, tape can be played back for superior
tone quality.
Synchro start dubbing function (normal/high speed
dubbing).
e Relay playback (from Deck B to Deck A).
3. “LIVE EFFEX” Sound System for the reproduction of
an expanded sound field.
4. Hyper-Bass Sound System with 3D super woofer.
. 5-Band graphic equalizer (S.E.A.) controls.
. CD IN jacks.
ac
* Dolby noise reduction manufactured under license from Dolby Labo-
ratories Licensing Corporation.
“DOLBY” and the double-D symbol []{Jare trademarks of Dolby Labo-
ratories Licensing Corporation.
4] Specifications
<Radio Section >
Frequency : FM 87.5— 108 MHz PC-Y777 B
ranges AM 522—1,629 kHz e
FM = 87.5—108 MHz
MW = 522-—-1,629 kHz -
SW 6—18 MHz i a
LW 144—288 kHz
FM 87.5—108 MHz
MW = 522—1,629 kHz :
SW 6—18 MHz POMEL
LW 144—288 kHz
Antennas : Telescopic antenna for FM
Ferrite core antenna PC-Y777 B
for AM
Telescopic antenna
ina eia ante (PC-Y777 E/G)
Ferrite core antenna
MW & LW
<Tape Recorder Section>
Track system : 4-track 2-channel stereo
Frequency : 40—14,000 Hz
response (with normal tape)
Wow & flutter: 0.15% (WRMS)
Fast wind time: Approx. 120 sec.
(Deck A: C-60 cassette)
Approx. 120 sec.
(Deck B: C-60 cassette)
<General >
3D system : ASW (Acoustic Super Woofer)
Power output 10W (5W + 5W) at 62 and 13 W
for 3D at 8 Q (Max.)
6 W (3 W + 3W) at 62 and
7 W for 3D at 8 Q (10% THD)
S.E.A. : S.E.A. center frequencies:
characteristics 100 Hz/330 Hz/1 kHz/3.3 kHz/
10 kHz
S.E.A. control range: +10 dB
(No, 1802)
“LIVE EFFEX"” Sound System
When stereo sources are heard from the speakers,
often the sound feels far more restricted than in a live
performance. This is because the stereo effect is
degraded due to crosstalk** between our left and right
ears. The PC-Y999/Y777 removes this acoustic cross-
talk between the ears using our newly developed
“LIVE EFFEX” signal sound processor; with this, the
sound image extends beyond the speakers, realizing
a natural stereo sound field.
** Crosstalk is a phenomenon in which sound from
two channels is mixed; in addition to hearing
sound from the right speaker, the right ear hears
sound from the left speaker, with a slight time
delay.
Input jacks
Output jacks
:CD IN xX 2 (440 mV/50 kQ)
: Speaker x 2 (Matching im-
pedance 6 — 16 )
Headphones x 1 (15 mW/32 Q,
Matching impedance 16 2—1 kQ)
: DC 12 V (8’°R20"' batteries)
AC 240 V, 50 Hz (PC-Y777 B)
AC 220 V, 50 Hz (PC-Y777 E/G)
Ext. DC IN 12 V
(Car battery via optional CN-332
car adapter)
Power consumption : 36 W (with POWER SW ON)
2.0 W
(with POWER SW STANDBY)
: 650(W) x 235(H) x 235(D) mm
including knob
Power supply
Dimensions
Weight : Approx. 6.9 kg (without batteries)
< Speaker Section >
(each unit)
Speaker :10cmx 1
Impedance 7:60
Dimensions : 155(W) x 215(H) x 195(D) mm
Weight : Approx. 1.1 kg
Design and specifications subject to change without notice.

| PC-Y777 B/E/G
[5]
Name
of
Controls
and
Their
Functions
@ Front panel
@ Top panel
@ Rear panel
@ Display window
© indicators (for tuner operation)
BAND indicator (FM1-FM2-MW-LW)
Radio frequency display
Preset station indicator
STEREO (FM stereo) indicator
@ BAND button
© Tuning control
DOWN frequency
UP frequency
© Preset station buttons
Cassette holder (Deck A)
Cassette hoider (Deck B)
@ VOLUME contro!
® Cassette operation buttons (Deck A)
O REC:
Press this button with the B® PLAY button for re-
cording.
bm» PLAY:
Press to play the tape.
@<REW:
Press to rewind the tape rapidly.
PP rF:
Press to wind the tape forward rapidly.
m/SSTOP/EJECT:
Press to stop the tape. Pressing this button after the
tape stops opens the cassette holder.
SUPAUSE:
Press to stop the tape temporarily. Press again to
release the pause mode.
@ HYPER-BASS switch and 3D indicator
-m= ON:
Set to this position to listen to Hyper-Bass Sound.
OFF:
Set to this position when Hyper-Bass Sound is not
required.
® This function does not work while headphones are being
used.
@ LIVE EFFEX switch and LE indicator
wm. ON:
Set to this position to listen to the LIVE EFFEX
sound.
OFF:
Set to this position when the LIVE EFFEX sound is
not required.
(No. 1802}
5
ih si pales es rh ai igen ce eiladllintadtin

PC-Y777 B/E/G
6
@® Cassette operation buttons (Deck B)
> PLAY:
Press to play the tape.
@<REW:
Press to rewind the tape rapidly.
PPFF:
Press to wind the tape forward rapidly.
@/SSTOP/EJECT: ;
Press to stop the tape. Pressing this button after the
tape stops opens the cassette holder.
@ TAPE (FOR PLAYBACK)/FM MODE switch
TAPE (FOR PLAYBACK) :
Set this switch according to the type of tape to be used.
«m=. METAL/CrO, : (Playback only)
Set to this position to listen to a metal (type IV) or
chrome (type II} tape.
NORMAL:
Set to this position to listen to a normal (type |) tape.
FM MODE switch:
-= MONO:
Set to this position when FM stereo reception is
obscured by noise.
STEREO:
Set to this position when listening to or recording an
FM stereo broadcast.
@ DOLBY NR switch
Set to ON { «=m ) when recording or playing back tapes
using the noise reduction system.
CONNECTIONS
@ Do not switch the power on until all the connections are
completed.
FM outdoor antenna
@ Headphones jack (PHONES) (3.5 mm dia. stereo mini
jack)
Connect headphones (impedance 1692 — 1k) to this
jack, The speakers are automatically switched off when
headphones are connected.
@ POWER switch
@ FUNCTION switch
TAPE-NORMAL SPEED DUBBING:
Set to this position when listening to a cassette or dub-
bing at normal speed.
TAPE-HIGH SPEED DUBBING:
Set to this position when dubbing at high speed.
TUNER:
Set to this position when listening to or recording from
the radio.
CD IN:
Set to this position when listening to or recording from
the source connected to the CD IN jacks.
5-BAND GRAPHIC EQUALIZER controls (S.E.A.)
Memory backup battery compartment cover
Telescopic antenna for FM reception
BEAT CUT switch
EXT ANT terminal for FM (PC-Y999E/Y777E)
@ CD IN jacks
Connect a CD player.
@ SPEAKER terminals
Connect the provided speakers to these terminals.
@ AC IN (AC input) jack
@® DC IN 12 V jack ( --®—+ ) (PC-Y999E/Y777E)
@) Battery compartment cover
Signal cord provided
with the CD player
{ To LINE OUT jacks
CD player (optional)
* Space for speaker cords
After connecting the speaker cords,
bundle any slack into the space for
the speaker cords in the rear panel.
@ When connecting the speaker cords, connect
the one marked with a jine to the ‘-” ter-
minal first.
—)
® Marked with line
Notes:
1, Connect the connection cords, etc, being sure not to
confuse channels or polarities. The wrong connection
will degrade the sound quality and stereo effect.
2. Be sure to connect the connection cords, etc. correctly.
Otherwise, there will be no sound or there will be noise.
(No. 1802)

PC-Y777 B/E/G
o|
Location of Main Parts
Speaker terminal Main. board CD IN jack
©, Tuner board
DC IN 12. V
Fig. 6-1 Beat cut switch
CD IN Beat cut switch SEA board
Tuner board
TT
i
Main board Fig. 6-2
(No. 1802) 7

PC-Y777 B/E/G |
DTS board ass’y
Mechanism ass’y
Fig. 6-3
Graphic equalizer ass’y
Fig. 6-4
8 (No. 1802)

U o)
1
~<
~J
si ie
wo
mi
Go)
~ Mechanism [Al ~ ~ Mechanism [B] ~
RF clutch ass’y RF clutch ass’y
t
Supply reel disk Take up reel disk Supply reel disk Take up reel disk
\
CO.
os
|
A
| |
Erase
head
Rec./playback
head
Main
belt
Playback
head
Fig. 6-5
Motor ass’y
RF clutch ass’y RF clutch ass'y
1 | |
Flywheel assy P. Kick lever (A) Flywheel ass’y
Fig. 6-6
(No. 1802) 9

PC-Y777 B/E/G |
Removal
of
Main
Parts
@ Rear Cover
1. Remove the battery cover (main battery).
2.
Remove
the
three
screws
@)
retaining
the
RCA
jack
and
top
side
of
the
rear
cover.
3.
Remove
the
five
screws
Q)
retaining
the
rear
cover
from
the
backside.
4.
Remove
the
two
screws
(3)
rataining
the
rear
cover
in
the
battery
box.
5.
Slightly
pull
out
the
rear
cover
and
remove
the
memory
battery
and
the
antenna
wire.
Memory
battery
.....
Preamplifier
circuit
board
Antenna
wire
.........
Tuner
board
@ Tuner Board Assembly
1.
remove
the
connector
(CN3)
and
the
flat
wire
(CN1)
from
the
DTS
board.
2.
Remove
the
output
cord
from
CN3
of
the
preamplifier
board.
3. Pull out the tuner board assembly.
ks | Fig. 7-1
Function knob
B Graphic Equalizer Assembly (SEA assembly)
1.
Pull
the
G.
equalizer
assembly
rearward
and
remove
the
cabinet.
2.
Remove
the
connection
wire
from
CN703
of
the
preamplifier
board.
3.
Remove
the
one
screw
retaining
the
G.
equalizer
board
assembly.
i
:
i
|
3
]
!
{
|
.
@ 3D Assembly
(with pre- and power board assemblies)
1. Remove the function switch knob.
2.
Remove
the
one
screw
(4)
located
under
the
function
knob.
3.
Remove
the
one
screw
6)
retaining
the
right
side
of
the
cabinet.
4. Pull out the volume knob.
. Remove the two screws 1) under the 3D case.
6.
Release
the
head
wire
and
the
motor/switch
wire
from
the
preamplifier
board.
Motor/switch
wire
Power
amplifier
board
CN802
B.
mechanism
Back view
oa
Preamplifier CN701 Remove the
head wire
A.
mechanism
connector
.
Preamplifier
CN702
if
necessary
head
wire
7. Pull out the 3D assembly.
Preamplifier Board Assembly
1.
Remove
the
four
screws
6)
retaining
the
preamplifier
board.
2. Remove the board assembly wire.
CN804 to the power board.
CN707 to the preamplifier board.
10 (No. 1802)