Sharp VC-M314 (serv.man2) Service Manual ▷ View online
43
VC-M314HM
VC-MH834HM
VC-MH834HM
YES
YES
YES
NO
NO
NO
FLOW CHART NO.1
1 SYSTEM CONTROL
TROUBLESHOOTING
No power is turned on.
Does power control (H) signal at
pin(94) of IC701 change from "L" to
"H" level?
Check IC701.
Does the base voltage of Q9904 or
Q9951 change from about 12.6V to
11.8V?
Check line between Q9904 or
Q9951, Q9905 and IC701.
Is voltage of 12V sent out from the
emitter of Q9904 or Q9951 transistor?
Check peripheral circuit of Q9904
or Q9951 and
A
T
12V line.
YES
YES
YES
NO
NO
Does the base voltage of Q9903
change from about 5.5V to 6.2V?
Check line between emitter of Q9904
or Q9951 and base of Q9903.
Is voltage of 5V sent out from the
emitter of Q9903 transistor?
Check peripheral circuit of Q9903
and
A
T
5V line.
Check peripheral circuit for poor
soldering.
NO
NO
NO
FLOW CHART NO.9 CASSETTE CONTROL
TROUBLESHOOTING(2)
A
cassette tape is taken in, but ejected at once.
Does the start sensor pulse at pin(79)
of IC701 change from "L" to "H" level
when the cassette tape is loaded?
Check line between start sensor
and pin(79) of IC701.
Does the end sensor pulse at pin(85)
of IC701 change from "L" to "H" level
when the cassette tape is loaded?
Check line between end sensor
and pin(85) of IC701.
Does the master cam mode
shifter operate normally when the
cassette tape is loaded?
Check line between cam switch
and IC701.
Replace IC701.
YES
YES
YES
FLOW CHART NO.10 LOADING MOT
OR
AND EJECT TROUBLESHOOTING
The cassette tape fails to come out.
Does the capstan motor start when
the EJECT
button is pressed?
See FLOW CHAR
T
NO.12
CAPST
AN MOT
OR
TROUBLE-
SHOOTING
Does the take-up reel disk turn
when the capstan motor is running?
Check line between take-up reel
sensor and pin(2) of IC701.
Is a "H" level applied at pin(12)
of IC7002 when a reel pulse has
been inputted?
Check line between pin(92) of
IC701 and pin(12) of IC7002.
Is the supply voltage of 12V fed
to pin(9) of IC7002?
Is the voltage about 10V sent out
from pin(15) of IC7002?
Check IC7002.
Is the specified voltage applied at
the loading motor terminal?
Check line between IC7002 and
loading motor
.
Does the loading motor run?
Replace cassette cam, gear
, etc.
YES
YES
YES
Check M 12V lines.
NO
YES
NO
YES
YES
YES
NO
NO
NO
NO
NO
Replace loading motor
.
44
VC-M314HM
VC-MH834HM
VC-MH834HM
FLOW CHART NO.13 DRUM MOT
OR TROUBLESHOOTING(1)
The drum motor fails to run.
Is the voltage more than about 2.6V
DC given out of pin(58) of IC701?
Check IC701.
NO
NO
NO
YES
YES
Check PC 5V
.
Is the supply voltage of 5V fed to
pin(3) of IC7002?
Is the voltage more than about 2.6V
DC given out of pin(2) of IC7002?
Check line between pin(58) of
IC701 and pin(2) of IC7002.
NO
YES
YES
Is the supply voltage of 12V fed
to pin(21) of IC7002?
Replace drum motor
.
Check M 12V line.
FLOW CHART NO.12 CAPST
AN MOT
OR TROUBLESHOOTING
The capstan motor fails to run.
Is the voltage more than about 2.6V
DC given out of pin(59) of IC701?
Check IC701.
NO
NO
NO
NO
NO
YES
YES
YES
YES
Is the supply voltage of 5V fed to
pin(8) of
AC connector?
Check PC 5V line.
Is the voltage more than 2.6V DC
sent in pin(4) of
AC connector?
Check line between the
AC
connector and pin(59) of IC701?
Is the voltage of pin(3) of
AC
connector 1.6~2.7V?
Check line between the pin(60) of
IC701 and pin(3) of
AC connector
.
Is the supply voltage of 12V/25V fed
to pin(5) of
AC connector?
YES
Replace capstan motor
.
Check MOT
OR Vcc line and motor
voltage selector circuit.
(Q9507, Q9508, Q9904, Q9951)
FLOW CHART NO.14 DRUM MOT
OR TROUBLESHOOTING(2)
The drum motor runs only for a few seconds.
Replace IC7002.
Check peripheral circuit of pins
(4), (5), (6) and (7) of IC7002.
Is drum PG signal given out from
the pin(7) of IC7002?
Is drum PG signal fed to pin(66)
of IC701?
Check line between pin(7) of
IC7002 and pin(66) of IC701.
Is head switching pulse sent out
from the pin(23) of IC701?
Check IC701.
Replace IC701.
NO
Check drum motor
.
YES
YES
YES
YES
NO
NO
NO
D-FG
about 5Vp-p
D-PG
about 5Vp-p
YES
NO
YES
YES
NO
NO
FLOW CHART NO.15 HEAD SWITCHING PULSE TROUBLESHOOTING.
No head switching pulse.
See FLOW CHAR
T
NO.13, 14
(DRUM MOT
OR
TROUBLESHOOTING(1), (2))
Is the drum motor rotating?
Is the drum PG signal and drum
FG signal present on pins(66)
and (65) of IC701, respectively?
Replace IC701.
Check line between IC7002
and IC701.
Check peripheral circuit of
IC7002.
Are the drum PG signal and drum
FG signal present on pins (7), (8)
of IC7002?
45
VC-M314HM
VC-MH834HM
VC-MH834HM
FLOW CHART NO.16 DRUM SER
VO TROUBLESHOOTING
Drum servo does not function.
Check peripheral circuit of X701.
Is there 14.318MHz oscillation at
pins(37) and (38) of IC701?
NO
In PB mode
YES
In REC mode
Is there drum FG signal at pin
(65) of IC701 present?
Is the V
-SYNC signal(reference)
at pin(50) of IC701?
YES
NO
NO
Check peripheral circuit of pin
(50) of IC701, C746, C747 and
R745.
Check drum FG signal line.
Is the head switching pulse at pin
(23) of IC701 present?
NO
See FLOW CHAR
T
NO.15
(HEAD SWITCHING PULSE
TROUBLESHOOTING.)
YES
YES
Is the drum
APC output at pin(34)
of IC701 and drum
AFC output at
pin(32) of IC701 present?
NO
Replace IC701.
YES
YES
Is the drum control voltage
applied to pin(2) of IC7002?
YES
Is pin(58) of IC701 in high
impedance?
NO
YES
NO
Check line between pins(34) and
(32) of IC701 and pin(29) of
IC7002.
Does the IC7002 operate
normally?
Replace IC701.
Replace drum motor
.
46
VC-M314HM
VC-MH834HM
VC-MH834HM
1
2
FLOW CHART NO.17 CAPST
AN SER
VO TROUBLESHOOTING
Capstan servo does not function.
Only PB mode inoperative
YES
Only REC mode inoperative
YES
YES
NO
YES
NO
NO
NO
NO
Check peripheral
circuit of pin(50)
of IC701, C746,
C747 and R745.
Is there 14.318MHz
oscillation at pins
(37) and (38) of
IC701?
Check peripheral
circuit of X701.
YES
YES
Dose pin(59) of
IC701 operate
normally?
Check "
1
"
Check "
2
"
Check capstan
motor unit and/or
replace.
Is there capstan
AFC and
APC
at pins(31) and
(33) of IC701?
Replace IC701.
Replace A/C
head.
YES
YES
YES
NO
NO
NO
Is there capstan
AFC signal at pin
(31) of IC701?
NO
NO
NO
Is there capstan
APC signal at pin
(33) of IC701?
YES
NO
Replace IC701.
Does PB CTL
signal appear at
pin (76) of IC701?
Replace IC701.
Is there REC CTL
signal output at
pins(75) and (74)
of IC701?
Does PB CTL
signal appear at
pin(76) of IC701?
Does A/C
head
operate
normally?
Adjust the height
of the
A/C head.
Does the capstan
FG signal appear
at pin (67) of IC-
701?
Check the capstan
FG signal line bet-
ween pin(6) of
AC
connector and pin
(67) of IC701.
Check peripheral
circuit of
AC
connector
.
Is the V
-SYNC
signal(reference) at
pin(50) of IC701?
Are REC and/or PB
mode inoperative?
NO
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