Jvc BP 5300 TR Service Manual Part 1

Page 1

2.1 GENERAL

The mechanical parts of this model have been consider
ably reduced in comparison to previous machines, result-
ing a simplified mechanism. Reliability is enhanced by
the diecast aluminum chassis, while the video head drum,
capstan and reels are driven directly by independent DC
motors.

Video cassette insertion and removal are easily per-
formed with the aid of motorized automatic front
loading system. The six motors and four solenoids are
controlled by the microprocessor of the system control
circuit which contributes to precise and reliable opera-
tion.

A description of the main mechanical functions is pro-
vided as follows.

2.2 MAIN COiMPONENT OPERATIONS

2.2.1 Motors

1. Drum motor
A direct drive (DD) motor is used in conjunction
with a drum servo circuit to control video head
rotation,

2. Capstan motor
The capstan motor includes a DC motor, capstan
FG, flywheel and capstan. During recording, play-
back, search and slow modes, the capstan motor is
controlled by capstan servo circuit and drives the
capstan in forward and reverse directions.

Capstan motor assembly

Fig. 2-7.

SECTION 2
MECHANISM DESCRIPTION

Take-up & supply loading rings TEkE-UP impedance roller

Srua l2) Upper drum

Supply impedance roller
\

Loading motor _;

After loading [AL] &
unloading (UL) switches \\\\

Cancel lever

Stud (1) oflower
(take-up) ring
Tension pole

Differential transformer --

Tension arm

C9

uvuwtf! u-
x ,M

Supply reel disk I Supply brake Take-up brake

I
|
|
r l i
|
I I
Supply reel motor

Loading tension solenoid

Fig. 2-1 Main parts Location

Tape guide (Reverse) solenoid

-Pinch roller solenoid

/ Audio erase head
/Audio/control head

/Tape guide

-=Pinch roller

- - HCapstan motor

\ Capstan

\ Take-up reel motor

\ Brake solenoid

2-1

Page 2

3.

Woiniwheel geav

Reel motors

Supply and take-up reel motors are controlled by
the reel servo circuit and directly drive the reels in
forward and reverse directions.

Loading motor

The loading motor drives the loading rings to ex-
tract the tape from the cassette during loading and
return it to the cassette during unloading.

The loading motor rotation goes via the loading
belt to the loading gear train Composed of worm,
wormwheel and relay gears. The supply loading
ring is driven via the worm and wormwheel gears,
while drive for the take-up loading ring is trans-
mitted by the relay gear.

4- .Unioading
fie . Loading

Relay my

0' m gleal

/ Loading motor
Loading txrlr

Fig. 2-3 Loading ring drive mechanism

Cassette housing motor

When a cassette tape is inserted slightly into the
front panel slot, the cassette housing motor moves
the cassette in the loading direction.

In the Eject mode, the cassette housing motor
rotates in the unloading direction.

2.2.2 Solenoids

1.

2-2

Brake solenoid

According to the selected mode, the brake solenoid
functions to engage or release the supply and take
up brakes.

Pinch roller solenoid

This solenoid engages and release the pinch roller
pressure. At the rotation end of the takeup load-
ing ring, the stud at the lower side of the take-up
loading ring switches on the AL laiter loading)
switch, then the pinch roller solenoid is engaged.

3. Tape guide (Reverse) solenoid
This solenoid is energized so that the tape guide
does not contact the video tape when the tape
travels in the Reverse Search mode.

4. Loading tension solenoid
The loading tension solenoid operates in all modes
except the Stop, Loading and Unloading modes in
order to release the loading tension brake from the
take-up reel disk.

2 .2 . 3 Cassette housing

A motorized front loading system is used for the cassette
housing which automatically performs loading and un-
loading of the cassette tape.

Fig. 24(3) indicates the state before a cassette is inserted.
Inserting a cassette forces the roller and sprocket gear-2
upwards. This pulls the chain taut and the shutter blocks
the cassette sensor. The cassette housing motor rotates
in the loading direction.

This rotation is transferred in the route: cassette housing
motor -> cassette belt -> worm v> relay gear -> sprocket
gear-1 -> chain. The chain turns counterclockwise.
Sprocket gear-2 and the roller also turn counter-clock-
wise, and the cassette slides toward the right, as shown
by Fig. 2-4lb).

When the cassette is fully positioned, it presses the slide
plate toward the right. The chain pin of the slide plate
shifts toward the right and engages a link of the chain.
As the chain rotates, the slide plate and housing are
lowered by gears, This is illustrated in Fig. 2-4lcl.

After lowering into the chassis, the cassette switch be-
comes on, but the cassette housing motor continues to
turn for another 300 msec. This compensates for possible
switch timing error and ensures proper positioning of the
housing. See Fig. 2-4id).

Pressing the EJECT button begins the unloading process,
which starts after the stop state is reached. In the Eject
mode, the cassette housing motor rotates in the unload-
ing direction.

Note: in the loading process, if the cassette switch is not
on within 5 seconds after the cassette housing
motor begins rotating, the Eject mode is auto-
matically entered.

Notes:

1. Take-up and other rotational torque values are
determined by voltages applied to the motors.

2. Since all mechanism functions are determined
electrically, also refer to the electrical circuit

descriptions of this manual.

Chain

Cassette housi ng motor

Roller

(a)

lcl

Sprocket gear-2 Cassette sensor Cassette tape l - Shun?"

Cassette belt i

«cu
L-s

W [bl

Cassette door

Slide plate
_ -+>
l
egg -
Cassette switch
it!)
Fig. 24 Cassette housing system

Page 8

2.3.8 FF (fast forward) mode

Pressing the FF button in the Stop mode switches on the
brake and loading tension solenoids. The supply, take-up
and loading tension brakes are released, freeing the reel
disks, and the reel motors turn in the fonNard direction.
The tape in the cassette becomes transferred from the
supply to the take-up reel.

At the end of tape or when the STOP button is pressed,
the reel motors stop and the brake and loading tension
solenoids switch off. All mechanical brakes are applied
to the reel disks and tape motion stops.

While the Play, Fonrvard Search, Reverse Search or Still
mode is in progress, pressing the FF button yields the
unloading mode at first. After completing the unloading
operation, the FF mode is produced.

2-8

Supply reel disk

_____f-___

I
I

l
I
Supply reel motor

Supply brake

Loading tension solenoid

Fig. 2-11

FF mode

Take-up brake

/ Loading tension brake
- Take-up reel motor
I _\ Take-up reel disk

l

l :
l

_ J

\
Brake solenoid

\

Page 21

4.

Other Circuits
During the Stop mode, pin 4 oi Ice is high and
|C7 turns on, R22 adjusts for minimum search
output voltage.

R24 adjusts for 2.7 i 0.05 V at this time output
voltage. lf the 7~pin remote controller is connected
and the search mode selected, the inputs lpins 5
and 6) of ICQ becomes high and 317 switches off
to shift priority the speed up/down command.

V. VOLTAGE CONTROL SYSTEM

H SPEED lJF
IL OTHER rlMEQ

lC IQ
output
Expander

orscnarg.

5 9V
\ e
i?
lay
RIZB REE

When the 45-pin remote controller is connected,
|C7 switches on and discharges through open
collector inverter |C32 and lC9. Forward and
reverse commands from IC29 do not function
since diodes 026 and D27 switch on through
open collector inverter |C10.

lzv

SVILL morn

IC 29 l5VTOI

~ :HrgnlON 9
cs msCHMGE rw
VOL, ice D C We m2 l
ham 7 em azuor: HvSEARCN LED on 026 1
lClE . a a . 5 ta FORWARD
tn»:
IClO on ICIO
REMOTE
no... JUNCYIUNf-mcsa-NZN 3 M K T 0 MREVERSE

H 457m REMOTE
L: OTHER riMEs

__J

3-17

3.2.14 Cassette motor drive circuit

This model is a front loading type which features motor-
ized insertion and ejection of the cassette. Presence of
a cassette is detected by an LED and photo interrrupter
system.

1. Description of lC3 (HA17555PSl
The HA17555PS is an IC which is capable of
accurate time delay or oscillation.

In these modes, the output pulse width is deter-
mined by either an external resistance or a capaci-
tance respectively.

1mm 45m" REMOTE
FJJi-II

0 Fig. 346 shows a monostable circuit using the
HA17555PS. Assure that external capaciter C is
discharged initially by transistor 02 within the IC.
A negative input pulse applied to the trigger
terminal sets the flipflop and switches 02 off,
yielding a high level output. Capacitor 09 is
charge through R13 with the time constant
determined by T = R13 x C9. When the voltage
between the terminals of capacitor C reaches
the threshold voltage of comparator A, the flipflop
is reset, 02 turns on and capacitor C discharges.
This returns the output to low level. During this
interval, again applying the pulse input will not
retrigger the monostable.

L = UNYIL 5 at!

[n wnsu EXCEEDS asv

CONNECTOR

E] JUNCTlON

L_ ________ .r

Fig. 3-15

P3345
annex 5}ch

SPEED CAPS mu
SERVO

m

lmuthN
(Nigm on

i3

2-0 o-LJ
IE?

966

XIO SPEED VOLYAGE

msv

Page 24

3.2.16 Counter circuit

The counter circuit consists of two microcomputers and
fluorescent display tubes, The circuit controls the
fluorescent display tubes to show the required mode
in accordance with commands from the syscon circuit.

For example, when a command signal is supplied to
ports PA and WT of |C1 (counter), and the lCl port PE
output goes to the PA port of 102 (driver), while the PD
and PE port outputs of |C1 become the drive signals for
the fluorescent display tubes. Colon display is driven by
port PD of IC1.

1. The tape counter counts up to i9999,
2. The lap counter counts up to 9'. 69: 59.

0| II I
i II I

LAP |:lO l-_ _

- |_l-' 7

L, _ _
lCZ FFO r 2 3 I 5 G Y

venue
on

en

PEG 53 Mllus lo M) Mmus
--....ms mm mm us

ca
l
l MINUS

Fig. 3-19

The Minus display changes to LAP display when
PFl of |C2 is high level, after which hour -> 10
rninUtes " minutes ~> 10 seconds 9 seconds data
are stored in the microcomputer for driving the
display tubes.

3. The tape pulse is obtained by 1/16 count down of
the reel FG pulse in the system control circuit.

4. Counter lC1 lUPDSS4-058) contains of two
memory counters, one for the reel pulse and the
other for the capstan pulse.

5. The up/down signal selects counting direction for
the tape and capstan pulses.

6. LAP SW
This is for switching the tape counter and LAP
displays.

7. Reset SW

When set on during LAP, the display tubes indi- '
care-

When set on during counter, the display tubes
indicate

8. Tape End
During recording, when 5 minites (about 0.7
meter) of tape remains, syscon commend to lCZ
flashes the display tubes.

3'20

9. Zero Out (counter output)
Reel FG pulses are counted during counter stop
and counter repeat operation. High is produced
when the tape counter display reaches zero. Since
counting is also performed during LAP operation,
high becomes produced at zero.

-o-o-o-o-----r-o-o- COUNTER
O

_J_l_____

Fig. 3-20

10. Access
In order to stop accurately at 0 in counter stop or
zero search operation, high supplied to the reel
servo decreases the speed for the 199 to 0 range

during FF/REW.

REW --i-l-O-
-99 0 99

__l-'->

FF __._._.4_.._.
-99 0 99

Fig. 3-21

3.2.17 Junction circuit

Commands enter this circuit from the 45-pin connector,
the front panel 7-pin connector, and from the main-
frame key. The commands are processed and sent to the
system control circuit. Refer to Fig. 3-22.

1. 45-pin remote control commands
Independently arriving commands are converted
to serial code by the encoder lC of the junction
board. (The operation of |C1 is outlined in 3.1.17
Operation-A).

The remote switching signal sets priority to the
45-pin remote control unit,

01: This transistor is for switching the REC and
AUD DUB modes.

2. When the 45-pin remote control unit is connected,
low from pin 11 of remote command P331 through
an open collector inverter switches |C2 on.

The search speed (V speed) output from P331 pin
14 is supplied to the system control via P335 pin 8
and IC2.

Page 26

3.2.18 Tape and solenoid control circuit

1. Search forward mode
When the tape end is detected during the search
forward mode, low output from pin 1 of P303
switches diode D32 on. Through open collector
inverter lC32, D6 becomes cutoff.

The resulting high goes to input pins 8 and 9 of
lC13, and low from output pin 10 switches on
diodes D36 and D37.

Low potential through |C30 inverter cuts off
010 and 014, at which time the brake and pinch
solenoids stop the reels.

Following this, a high pulse from lC13 pin 28 (X2

speed) is supplied to pin 5 of IC13, yielding low
from pin 4. Via open collector inverter ICS, high
switches on diodes 034 and D35, and drives 09
and 013. The brake and pinch solenoids are
energized through inverter |C31 and rewind of
the trailer tape starts. Afterwards, the Still mode
becomes set.

2. Search reverse mode
When the tape start is detected during the search
reverse mode, the leader tape is rewound and the
Still mode entered.

The operation principle is the same as the search
forward mode.
Timing chart is shown in Fig, 3-23.

TAPE END ouRmG SEARCH MODE

CAFSTAN , MOTOR
l6 Is .30

CAFSTAN 7 REVERSE
ic re 7 l7

x2 lClS-ZS

F0 STOP lC25-36

PmcH, BRAKE

SOLENOID

LAPFROX 0.6: cl TAPE STARI

XlO IC29-27

STAET
SENSOR
\

Pso:

um Icm-zs
amt SOL'I

L APPROX 0.5:

at TAFE sue a. men H ior 0.3:

NAPFROX 0.65 in TAPE ENo,rAPE sub". nom

L m 03: m neg END.

lrwnns
PARENT RECORDING up;

_;l-
_+-l_

___'ll_

anAkE SOLENOID

Em, n92
K232
ssuson L_~ia" pa lell 1
\\ 3 . ID L-H .
a
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immune-23 (m "79
amen SOL-I
homers-21
no /
n m 035 at rue: Erin,
mes sum.
lrum icIe-su L
sax SOL-Z
K034 Fl
NC SOLENOID
IrnmILIQ-ll Hie!- 33 H 5'9'3 '55 mom
eur LED 4 '3
N-L
\ :
L-u

tunnels-29 u..-m5n
x2 Irom leis-2n
FINCM soL-z

LAPPnox 03: ul TAPE END, TAPE srARr.
THEN H m o};

3-22

CAP REvloM stun)

3.2.19 Long still (ICZS, HA17555PS)

Excessive duration of the Still mode is detrimental to
the tape and magnetic heads. Therefore, two or three
minutes after the Still mode has been entered, the mono-
stable multivibrator of 1028 produces the long still com-
mand for reducing reel servo tension at the supply reel.
The timing Chart is shown in Fig. 3-24.

Sun

STILL LED Li-

AFPROX . 2Min 30:

fl 75mg: REVERSE ROTATION
CAP MOYEH TO SLACKEN TAPE.

LONG STILL J

Fig. 3-24

CAP REV

3-22

3.2.20 Pause, Still and Pre-roll

Simultaneously pressing the record and play keys during
the Play mode yields the Recording mode. At this time,
pressing the pause key produces Pause mode after about
2.4 seconds of tape rewind.

Again pressing the play key releases the Pause mode and
recording is resumed after 2.4 seconds of playback. This
process serves to avoid disruption at the recording junc-
ture (editing point).

If the ore-roll key of the remote control unit is pressed.
the tape becomes rewound at X2 speed for 4 seconds,
then at l/Espeed forl second.

When the still key is pressed during the Play mode, the
capstan motor stops and the Still mode becomes set.

lei-l

[// // //// //fl_

PRE - ROLL '

.Ei

e31 i

Fig. 3-25