VC-MH705 (serv.man7). Mechanism trouble shooting guide - Sharp VCR Service Manual (repair manual)

vc-mh705 (serv.man7) service manual
Model
VC-MH705 (serv.man7)
Pages
6
Size
33.37 KB
Type
PDF
Document
Service Manual
Brand
Device
VCR / Mechanism trouble shooting guide
File
vc-mh705-sm7.pdf
Date

Read Sharp VC-MH705 (serv.man7) Service Manual online

35
VC-MH705HM/LM
VC-MH815HM/LM,MH85HM
VC-MH715HM,MH835HM
Loading motor turns in reverse
direction and master cam
clockwise.
CASSETTE INSERTION     STOP
Cassette
inserting
Full-
loading
YES
YES
YES
NO
NO
Loading motor starts in forward
direction and master cam counter
clockwise.
Does mechanism position sw.
come off within 2.5 sec.?
Are start/end sensors at low level
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.
Start sensor close.
(Cassette is judged
caught halfway.)
(Cassette LED or some other part
is judged defective.)
6. MECHANISM OPERA
TION 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
Code 1
(Mode SW/outside)
Code 2
(Mode SW/inside)
CS/EJ
UL
PU1
PU2
VSR
PB
STILL
SLOW
REW
FF
ST
OP
36
VC-MH705HM/LM
VC-MH815HM/LM,MH85HM
VC-MH715HM,MH835HM
STOP      REC/PLAY
PLAY     STILL
PLAY     VSR
VSR      PLAY
Capstan motor turns
counterclockwise.
Is take-up reel sensor signal
outputted ?
End
Press REC/PLAY key.
Picture appears.
Unloading
Set capstan motor to search
speed.
End
Press FF key.
PLAY      VSF
REC/PLAY      STOP
Capstan motor turns in
reverse direction.
Loading motor turns in
forward direction and master 
cam CCW.
Slow brake comes into
contact with capstan motor.
Slow brake
pressing
Mode switch is at STILL
position.
End
Capstan motor stops.
Press STOP key.
Loading motor stops.
End
Stop capstan motor.
NO
YES
Press STILL key.
Pinch
roller
releasing
Idler
swinging
Pinch
roller
pressing
Loading motor turns reverse
direction and master cam 
clockwise.
Turn capstan motor in
reverse direction.
Turn loading motor forward 
direction.
Mode switch is at VSR
position.
Set capstan motor to search
speed.
Is take-up reel sensor signal
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
Release the supply main 
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.
Capstan motor turns
counterclockwise. PB speed.
NO
YES
37
VC-MH705HM/LM
VC-MH815HM/LM,MH85HM
VC-MH715HM,MH835HM
STOP      FF/REW
STOP      CASSETTE EJECT
FF/REW      STOP
NO
NO
FF/REW
operation
Brake
function
Turn capstan motor in
normal or reverse direction,
after the remaining tape has
been detected.
Loading motor turns forward
direction.
Mode switch is at Stop
position.
End
Press STOP key.
Press FF/REW key.
Stop capstan motor.
Mode SW is at FF/REW 
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.
4 supply reel pulses
outputted ?
Does the take-up
reel pulse output
two edges ?
Capstan motor turns
clockwise.
Loading motor turns
reverse direction.
Mode switch is at
Eject position.
Loading motor
stops.
Capstan motor
stops.
Press EJECT key.
Tape
unloading
Cassette
eject
End
Capstan motor turns
clockwise.
Capstan motor turns
counterclockwise in about
2 seconds.
Stop loading motor.
Capstan motor turns in reverse direction.
Mode switch is at UL position.
YES
YES
38
VC-MH705HM/LM
VC-MH815HM/LM,MH85HM
VC-MH715HM,MH835HM
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 ?
Does loading
motor operate ?
Modes changing
smoothly through
mode switch ?
Loading motor
control system
in trouble.
Are Vco 24V and
Vcc 5V applied ?
Replace the
capstan motor.
Replace the idler
ass’y.
Replace the reel
sensor.
Is voltage applied
to loading motor ?
Loading motor is
damaged. Replace
it.
Voltage supply
system in trouble.
Mode SW in 
trouble or master 
cam malpositioned.
Voltage supply
system in trouble.
Does capstan
motor turn in FF (or
REW) direction ?
Are idler wheel
ass’y and reel disk
in mesh ?
Is the pulse
outputted from reel
sensor ?
The cassette tape
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 ?
Does loading
motor operate ?
Modes changing
smoothly through
mode switch ?
Loading motor
control system
in trouble.
Are Vco 24V and
Vcc 5V applied ?
Replace the
capstan motor.
Replace the idler
ass’y.
Replace the reel
sensor.
Is voltage applied
to loading motor ?
Loading motor is
damaged. Replace
it.
Voltage supply
system in trouble.
Voltage supply
system in trouble.
Does capstan
motor turn ?
Are idler wheel
ass'y and reel disk
in mesh ?
Is the pulse 
outputted from reel
sensor ?
Check main PWB.
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Here you can read online and download Sharp VC-MH705 (serv.man7) Service Manual in PDF. VC-MH705 (serv.man7) service manual will guide through the process and help you recover, restore, fix, disassemble and repair Sharp VC-MH705 (serv.man7) VCR. Information contained in service manuals typically includes schematics / circuit diagrams, wiring diagrams, block diagrams, printed wiring boards, exploded views, parts list, disassembly / assembly, pcb.