Read Sharp VC-MH75 (serv.man8) Service Manual online
34
VC-MH75HM
Loading motor turns in reverse
direction and master cam
clockwise.
direction and master cam
clockwise.
CASSETTE INSERTION STOP
Cassette
inserting
inserting
Full-
loading
loading
YES
YES
YES
NO
NO
Loading motor starts in forward
direction and master cam counter
clockwise.
direction and master cam counter
clockwise.
Does mechanism position sw.
come off within 2.5 sec.?
come off within 2.5 sec.?
Are start/end sensors at low level
before cassette insertion ?
before cassette insertion ?
Insert cassette.
Drum motor starts.
Tape loading.
Pinch roller comes into contact.
Mode switch is at PB position.
Loading motor stop.
NO
Unloading
Is drum FG pulse outputted ?
End
End
Cassette is ejected and loading
motor stops.
motor stops.
Start sensor close.
(Cassette is judged
caught halfway.)
caught halfway.)
(Cassette LED or some other part
is judged defective.)
is judged defective.)
6. MECHANISM OPERATION FLOWCHART AND TROUBLESHOOTING GUIDE
MECHANISM OPERATION FLOWCHART
* This flowchart describes the outline of the mechanism’s operation, but does not give its details.
1
0
1
1
1
1
1
1
1
1
1
0
1
0
1
0
0
0
1
0
1
0
0
0
1
0
0
0
0
0
1
0
0
0
1
0
1
0
0
0
1
0
S Sensor
Open
Close
1
1
1
0
0
0
0
0
0
0
1
1
1
1
0
1
1
0
CS/EJ
ULD
PU1
PU2
VSR
PB
SLOW
FF
STOP
Code 1
Code 2
S Sensor
EJ
UL
PU
PU2
VSR
PB
SLW
FF
STP
0
1
1
0
1
1
0
0
0
0
0
1
0
0
1 or 0
Code 1
(Mode SW/outside)
Code 2
(Mode SW/inside)
Mecha Mode
60
0
120
180
240
300
360
Mecha Mode
Mode check
Cam mark
Cam mark
Code 1
(Mode SW/outside)
Code 2
(Mode SW/inside)
CS/EJ
UL
PU1
PU2
VSR
PB
STILL
SLOW
SLOW
REW
FF
FF
STOP
35
VC-MH75HM
STOP REC/PLAY
PLAY STILL
PLAY VSR
VSR PLAY
Capstan motor turns
counterclockwise.
counterclockwise.
Is take-up reel sensor signal
outputted ?
outputted ?
End
Press REC/PLAY key.
Picture appears.
Unloading
Set capstan motor to search
speed.
speed.
End
Press FF key.
PLAY VSF
REC/PLAY STOP
Capstan motor turns in
reverse direction.
reverse direction.
Loading motor turns in
forward direction and master
cam CCW.
forward direction and master
cam CCW.
Slow brake comes into
contact with capstan motor.
contact with capstan motor.
Slow brake
pressing
pressing
Mode switch is at STILL
position.
position.
End
Capstan motor stops.
Press STOP key.
Loading motor stops.
End
Stop capstan motor.
NO
YES
Press STILL key.
Pinch
roller
releasing
roller
releasing
Idler
swinging
swinging
Pinch
roller
pressing
roller
pressing
Loading motor turns reverse
direction and master cam
clockwise.
direction and master cam
clockwise.
Turn capstan motor in
reverse direction.
reverse direction.
Turn loading motor forward
direction.
direction.
Mode switch is at VSR
position.
position.
Set capstan motor to search
speed.
speed.
Is take-up reel sensor signal
outputted ?
outputted ?
Press REW key.
Release pinch roller.
Mode switch is at PU2 position.
Mode switch is at PU1 position.
Stop loading motor.
Press pinch roller.
Loading motor turns reverse
direction
direction
Release the supply main
brake.
brake.
Stop loading motor.
End
Unloading
Mode switch is at PB position.
End
Press PLAY Key.
Loading motor turns forward
direction and master cam
CCW.
direction and master cam
CCW.
Capstan motor turns
counterclockwise. PB speed.
counterclockwise. PB speed.
NO
YES
36
VC-MH75HM
STOP FF/REW
STOP CASSETTE EJECT
FF/REW STOP
NO
NO
FF/REW
operation
operation
Brake
function
function
Turn capstan motor in
normal or reverse direction,
after the remaining tape has
been detected.
normal or reverse direction,
after the remaining tape has
been detected.
Loading motor turns forward
direction.
direction.
Mode switch is at Stop
position.
position.
End
Press STOP key.
Press FF/REW key.
Stop capstan motor.
Mode SW is at FF/REW
position.
position.
Loading motor rotate forward.
Loading Motor stop rotate.
Mode SW at PB position.
Loading motor reverse direction.
Loading Motor stop rotate.
Loading motor stops.
End
Loading motor turns in reverse direction and master cam
clockwise.
clockwise.
4 supply reel pulses
outputted ?
outputted ?
Does the take-up
reel pulse output
two edges ?
reel pulse output
two edges ?
Capstan motor turns
clockwise.
clockwise.
Loading motor turns
reverse direction.
reverse direction.
Mode switch is at
Eject position.
Eject position.
Loading motor
stops.
stops.
Capstan motor
stops.
stops.
Press EJECT key.
Tape
unloading
unloading
Cassette
eject
eject
End
Capstan motor turns
clockwise.
clockwise.
Capstan motor turns
counterclockwise in about
2 seconds.
counterclockwise in about
2 seconds.
Stop loading motor.
Capstan motor turns in reverse direction.
Mode switch is at UL position.
YES
YES
37
VC-MH75HM
MECHANISM TROUBLESHOOTING
1. FF/REW FAILURE (NO TAPE WINDING)
Press FF key.
NO
NO
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
YES
YES
YES
Is master cam at
FF position ?
FF position ?
Does loading
motor operate ?
motor operate ?
Modes changing
smoothly through
mode switch ?
smoothly through
mode switch ?
Loading motor
control system
in trouble.
control system
in trouble.
Are Vco 24V and
Vcc 5V applied ?
Vcc 5V applied ?
Replace the
capstan motor.
capstan motor.
Replace the idler
ass’y.
ass’y.
Replace the reel
sensor.
sensor.
Is voltage applied
to loading motor ?
to loading motor ?
Loading motor is
damaged. Replace
it.
damaged. Replace
it.
Voltage supply
system in trouble.
system in trouble.
Mode SW in
trouble or master
cam malpositioned.
trouble or master
cam malpositioned.
Voltage supply
system in trouble.
system in trouble.
Does capstan
motor turn in FF (or
REW) direction ?
motor turn in FF (or
REW) direction ?
Are idler wheel
ass’y and reel disk
in mesh ?
ass’y and reel disk
in mesh ?
Is the pulse
outputted from reel
sensor ?
outputted from reel
sensor ?
The cassette tape
is presumably
damaged.
is presumably
damaged.
2. REC/PLAY FAILURE (MODE RELEASE)
NO
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
YES
YES
YES
Is the master cam
at PB position ?
at PB position ?
Does loading
motor operate ?
motor operate ?
Modes changing
smoothly through
mode switch ?
smoothly through
mode switch ?
Loading motor
control system
in trouble.
control system
in trouble.
Are Vco 24V and
Vcc 5V applied ?
Vcc 5V applied ?
Replace the
capstan motor.
capstan motor.
Replace the idler
ass’y.
ass’y.
Replace the reel
sensor.
sensor.
Is voltage applied
to loading motor ?
to loading motor ?
Loading motor is
damaged. Replace
it.
damaged. Replace
it.
Voltage supply
system in trouble.
system in trouble.
Voltage supply
system in trouble.
system in trouble.
Does capstan
motor turn ?
motor turn ?
Are idler wheel
ass'y and reel disk
in mesh ?
ass'y and reel disk
in mesh ?
Is the pulse
outputted from reel
sensor ?
outputted from reel
sensor ?
Check main PWB.