Sharp VC-M314 (serv.man2) Service Manual ▷ View online
39
VC-M314HM
VC-MH834HM
VC-MH834HM
Replace loading motor block.
3. WINDING FAILURE AT VSR
4. UNUSUAL SOUND IN EACH MODE
Is Playback
function normal ?
Master cam
shifting to VSR
position ?
Go to 2. REC/
PLAY FAILURE
routine.
Replace idler
gear ass’y.
Replace limiter
pulley ass’y.
Replace reel
sensor.
Go to 2. REC/
PLAY FAILURE
routine.
Are idler wheel
ass’y and supply
reel disk in mesh ?
Is supply reel disk
winding torque
normal ?
Is pulse outputted
from reel sensor?
Check main PWB.
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
YES
YES
NO
NO
YES
Press REW key.
4-i) Unusual sound in cassette
insertion and ejection mode
Is unusal sound heard during
cassette coutrol running ?
Unusual sound heard with pinch
roller lever going up or down ?
Is unusual sound heard during
loading/unloading ?
Check pinch roller drive cam, pinch roller
drive lever and reverse guide for their actions.
Replace damaged one with new one.
Replace cassette control ass’y.
40
VC-M314HM
VC-MH834HM
VC-MH834HM
YES
YES
NO
NO
NO
NO
YES
YES
Replace capstan motor.
4-ii) Unusual sound in FF/REW mode
Is reel disk height as specified ?
Thrust gap found at reel disk ?
Drive system out of contact with any
part on main PWB ?
Turn capstan motor by hand.
Unusual sound heard ?
Check drive system’s gears for
damage. Replace damaged gear
with new one.
• Reel disk
• Limiter pulley ass’y
• Idler wheel ass’y
Check reel disk and main chassis.
And replace defective parts.
Adjust reel disk height.
Rearrange the parts on main PWB.
41
VC-M314HM
VC-MH834HM
VC-MH834HM
7. ELECTRICAL
TROUBLESHOOTING
FLOW CHART NO.1 POWER TROUBLESHOOTING(1)
No power
Unplug the
AC power cord.
Replug it a few minutes later
.
See FLOW CHAR
T
NO.2 POWER
TROUBLESHOOTING(2)
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
Is the fuse good?
Replace fuse.
Is
A
T
5V voltage line normal?
Check primary circuit.
Are A
T
42V
, A
T
23V
, A
T
12.6V
,
and filament voltage lines normal?
Check each rectifier circuits and
short-circuit of secondary circuit.
Is "H" level applied at pin(1) of
IC701?
Check peripheral circuits Q9603
and P-F
AIL
(L) signal line etc.
Check system control circuit
(IC701).
FLOW CHART NO.3 POWER TROUBLESHOOTING(3)
In case of abnormal noise(sound)
Check D9603, D9604, D9605
and D9606.
The D9603, D9604, D9605 and
D9606 as a result of check
if poor the replace.
NO
FLOW CHART NO.2 POWER TROUBLESHOOTING(2)
In case of Fuse(F901) blown out.
Replace F901, Q901 and R904,
check D910, D91
1, D912 and
D913 as aresult of check, if poor
,
replace at the same time.
Check short-circuit or leak of
D9603, D9604, D9605, D9606
and secondary circuit.
FLOW CHART NO.5 TIMER TROUBLESHOOTING (1)
The LCD display fails to light up.
Is the supply voltage of 5V fed to
pin(37) of IC8001?
Check STBY
5V line.
Is the supply voltage of 3.4V
, 1.7V
feed to pin(38) and pin(39) of IC8001?
Check pin(38), (39) of IC8001
and peripheral circuits.
Is it possible to confirm signals
LCD RESET
, LCD CS, LCD CLOCK
and LCD DA
T
A
on the pins(36),
(42), (43) and (44) of IC8001?
Are the segment signals
supplied to the LCD display
(LC8001) fromthe driver IC
(IC8001)?
Check peripheral circuit of pin(41)
of IC8001.
Check that the LCD display is
free from damages such as
crack.
Replace IC8001.
YES
YES
YES
YES
NO
NO
NO
NO
NO
YES
YES
YES
NO
NO
NO
FLOW CHART NO.4 POWER TROUBLESHOOTING(4)
In case of output voltage at low level.
Check peripheral circuits IC901,
IC9601, C9613, R9608, R9609,
R9610 and R961
1.
The IC901, IC9601, C9613, R9608,
R9609, R9610 and R961
1 as a result
of check, if poor the replace.
Check IC901 and peripheral
circuits.
Replace Q902.
Check short-circuit or leak of
T901.
Replace T901.
Check primary circuit and peripheral
circuit of Q901 and Q902.
Check the signal line between
IC701 and IC8001.
YES
IC8001 present?
Is the OSC signal at pin(41) of
42
VC-M314HM
VC-MH834HM
VC-MH834HM
Is the cassette housing
distorted?
NO
YES
YES
YES
YES
NO
YES
NO
NO
YES
NO
YES
FLOW CHART NO.8 CASSETTE CONTROL
TROUBLESHOOTING(1)
A
cassette tape is not take in.
NO
NO
Check start sensor cover
.
Check line between start sensor
and pin(79) of IC701.
Check line between pin(93) of
IC701 and pin(1
1) of IC7002.
Is the supply voltage of 12V fed
to pin(9) of IC7002?
Check M 12V lines.
Check IC7002.
Check line between IC7002 and
loading motor
.
Replace loading motor
.
Is the specified voltage applied
at the loading motor terminal
when the cassette tape is inserted?
Does pin(13) of IC7002 change to
about 10V when the cassette
tape in inserted?
Does pin(1
1) of IC7002 go to a
"H" level when the cassette tape
is inserted?
Does pin(79) of IC701 change
from "H" to "L" level when the
cassette tape is inserted?
Does the start sensor cover go
to open when the cassette tape
is inserted?
Does the key switch make good
contact, when the cassette tape is
inserted?
Check switch contact.
Is there the function control voltage
inputted at the pins(87) and (88) of
IC701, when the keys are activated?
Replace IC701.
Check peripheral circuit of pins(87) and
(88) of IC701, and the function keys.
YES
NO
NO
YES
Key-in input is not received
SWITC
FUNCTION
SWITC
FUNCTION
Ref No. Ref No.
NOP
NOP
5.000V
SW889
REW
P801
CASSETTE
4.279V
SW893
FF
NOP
3.694V
SW892
REC
SW817
SP/LP/EP
3.081V
SW894
PLA
Y
P802
TEST
2.561V
SW891
P
AUSE
SW816
CH+
1.864V
SW890
ST
OP
SW814
MENU
1.250V
SW810
SET
SW81
1
EJECT
0.625V
SW815
CH(-)
SW813
POWER
0.000V
KEY
-1 IN
KEY
-0 IN
TERMINAL
(Pin87 of IC701)
(Pin88 of IC701)
VOL
T
AGE
FLOW CHART NO.7 INFRARED R/C TROUBLESHOOTING
No operation is possible from the infrared remote control.
Dose the infrared remote control
function?
Replace infrared remote control
as required.
Is the supply voltage of 5V fed to
pin(3) of RMC831.
Check
A
T
5V and GND lines.
Is "L" pulse sent out from pin(1) of
the receiver when the infrared remote
control is activated?
Replace receiver
.
Check between at pin(1) of receiver
and all the way up thru to pin(5) of
IC701.
Replace IC701.
YES
NO
YES
NO
NO
NO
YES
A/D KEY
INPUT
SPECIFICA
TION:-
FLOW CHART NO.6 TIMER TROUBLESHOOTING (2)
Fix or replace the cassette
housing.
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