Sharp VC-M315HM (serv.man7) Service Manual ▷ View online
39
VC-M305HM/LM
VC-M315HM/LM
7. ELECTRICAL TROUBLESHOOTING
FLOW CHART NO.1 POWER TROUBLESHOOTING(1)
No power
Unplug the AC power cord.
Replug it a few minutes later.
Replug it a few minutes later.
See FLOW CHART NO.2 POWER
TROUBLESHOOTING (2).
TROUBLESHOOTING (2).
YES
YES
YES
YES
NO
NO
NO
NO
Is the fuse good?
Replace fuse.
Is AT 5V voltage line normal?
Check primary circuit.
Are AT 39V, AT 25V, AT 12V,
and filament voltage lines normal?
and filament voltage lines normal?
Check each rectifier circuits and
short-circuit of secondary circuit.
short-circuit of secondary circuit.
Is "H" level applied at pin(1) of
system CTL circuit IC701?
system CTL circuit IC701?
FLOW CHART NO.3 POWER TROUBLESHOOTING(3)
In case of abnormal noise(sound)
Check D931, D932, D933
and D934.
and D934.
The D931, D932, D933 and
D934 as a result of check
if poor the replace.
D934 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 check
D901, D902, D903 and D904 as
aresult of check, if poor, replace at
the same time.
D901, D902, D903 and D904 as
aresult of check, if poor, replace at
the same time.
Check short-circuit or leak of
D931, D932, D933, D934 and
secondary circuit.
D931, D932, D933, D934 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?
pin(37) of IC8001?
Check AT 5V line.
Is the supply voltage of 3.4V, 1.7V
feed to pin(38) and pin(39) of IC8001?
feed to pin(38) and pin(39) of IC8001?
Check pin(38), (39) of IC8001
and peripheral circuits.
and peripheral circuits.
Is it possible to confirm signals
LCD RESET, LCD CS, LCD CLOCK
and LCD DATA on the pins(36),
(42), (43) and (44) of IC8001?
LCD RESET, LCD CS, LCD CLOCK
and LCD DATA on the pins(36),
(42), (43) and (44) of IC8001?
Are the segment signals
supplied to the LCD display
(LC8001) fromthe driver IC
(IC8001)?
supplied to the LCD display
(LC8001) fromthe driver IC
(IC8001)?
Check peripheral circuit of pin(41)
of IC8001.
of IC8001.
Check that the LCD display is
free from damages such as
crack.
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,
IC903, C9336, R930, R932 and
R933.
IC903, C9336, R930, R932 and
R933.
The IC901, IC903, C9336, R930,
R932 and R933 as a result
of check, if poor the replace.
R932 and R933 as a result
of check, if poor the replace.
Check IC901 and peripheral
circuits.
circuits.
Replace Q902.
Check short-circuit or leak of
T901.
T901.
Replace T901.
Check primary circuit and peripheral
circuit of Q901 and Q902.
circuit of Q901 and Q902.
Check the signal line between
IC701 and IC8001.
IC701 and IC8001.
YES
IC8001 present?
Is the OSC signal at pin(41) of
40
VC-M305HM/LM
VC-M315HM/LM
SWITC
FUNCTION
SWITC
FUNCTION
TERMINAL
Ref No. Ref No.
VOLTAGE
S805
SET
S801
POWER
0.000V
S806
CH(+)
S802
EJECT
0.652V
S807
PAUSE
S803
MENU
1.864V
S808
REC
S804
CH(-)
2.561V
S883
NO USE
S881
PLAY
S884/S885
REW
S882
STOP
3.081V
S886/S887
FF
TP801
TEST
3.694V
-
-
TP802
CASSETTE
4.279V
-
-
-
-
5.000V
KEY-1 IN
KEY-0 IN
(Pin88 of IC701)
(Pin89 of IC701)
Is the cassette housing
distorted?
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(87) of IC701.
and pin(87) of IC701.
Check line between pin(92) of
IC701 and pin(10) of P701.
IC701 and pin(10) of P701.
Is the supply voltage of 12V fed
to pin(8) of P701?
to pin(8) of P701?
Check M 12V lines.
Check IC on mechanism.
Check line between IC on mechanism
and loading motor.
and loading motor.
Replace loading motor.
Is the specified voltage applied
at the loading motor terminal
when the cassette tape is inserted?
at the loading motor terminal
when the cassette tape is inserted?
Does IC on mechanism output
about 10V when the cassette
tape in inserted?
about 10V when the cassette
tape in inserted?
Does pin(10) of P701 go to a
"H" level when the cassette tape
is inserted?
"H" level when the cassette tape
is inserted?
Does pin(87) of IC701 change
from "H" to "L" level when the
cassette tape is inserted?
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?
to open when the cassette tape
is inserted?
Does the key switch make good
contact, when the cassette tape is
inserted?
contact, when the cassette tape is
inserted?
Check switch contact.
Is there the function control voltage
inputted at the pins(88) and (89) of
IC701, when the keys are activated?
inputted at the pins(88) and (89) of
IC701, when the keys are activated?
Replace IC701.
Check peripheral circuit of pins(88) and
(89) of IC701, and the function keys.
(89) of IC701, and the function keys.
YES
NO
NO
YES
Key-in input is not received
FLOW CHART NO.7 INFRARED R/C TROUBLESHOOTING
No operation is possible from the infrared remote control.
Does the infrared remote control
function?
function?
Replace infrared remote control
as required.
as required.
Is the supply voltage of 5V fed to
pin(2) of RMC801.
pin(2) of RMC801.
Check AT 5V and GND lines.
Is "L" pulse sent out from pin(1) of
the receiver when the infrared remote
control is activated?
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(4) of
IC701.
and all the way up thru to pin(4) of
IC701.
Replace IC701.
YES
NO
YES
NO
NO
NO
YES
A/D KEY INPUT
SPECIFICATION:-
FLOW CHART NO.6 TIMER TROUBLESHOOTING (2)
Fix or replace the cassette
housing.
housing.
41
VC-M305HM/LM
VC-M315HM/LM
YES
YES
YES
NO
NO
NO
FLOW CHART NO.11 SYSTEM CONTROL TROUBLESHOOTING
No power is turned on.
Does power control (H) signal at
pin(96) of IC701 change from "L" to
"H" level?
"H" level?
Check IC701.
Does the base voltage of Q966
change from about 12.6V to 11.8V?
change from about 12.6V to 11.8V?
Check line between Q966, Q967 and
IC701.
IC701.
Is voltage of 12V sent out from the
collector of Q966 transistor?
collector of Q966 transistor?
Check peripheral circuit of or Q966
and AT 12V line.
and AT 12V line.
YES
YES
YES
NO
NO
Does the base voltage of Q961
change from about 5.5V to 6.2V?
Check line between emitter of or Q966
and base of Q961.
and base of Q961.
Is voltage of 5V sent out from the
emitter of Q961 transistor?
emitter of Q961 transistor?
Check peripheral circuit of Q961 and
AT 5V line.
AT 5V line.
Check peripheral circuit for poor
soldering.
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(87)
of IC701 change from "L" to "H" level
when the cassette tape is loaded?
of IC701 change from "L" to "H" level
when the cassette tape is loaded?
Check line between start sensor
and pin(87) of IC701.
and pin(87) of IC701.
Does the end sensor pulse at pin(86)
of IC701 change from "L" to "H" level
when the cassette tape is loaded?
of IC701 change from "L" to "H" level
when the cassette tape is loaded?
Check line between end sensor
and pin(86) of IC701.
and pin(86) of IC701.
Does the master cam mode
shifter operate normally when the
cassette tape is loaded?
shifter operate normally when the
cassette tape is loaded?
Check line between cam switch
and IC701.
and IC701.
Replace IC701.
YES
YES
YES
FLOW CHART NO.10 LOADING MOTOR AND EJECT TROUBLESHOOTING
The cassette tape fails to come out.
Does the capstan motor start when
the EJECT button is pressed?
the EJECT button is pressed?
See FLOW CHART NO.12
CAPSTAN MOTOR TROUBLE-
SHOOTING
CAPSTAN MOTOR TROUBLE-
SHOOTING
Does the take-up reel disk turn
when the capstan motor is running?
when the capstan motor is running?
Check line between take-up reel
sensor and pin(2) of IC701.
sensor and pin(2) of IC701.
Is a "H" level applied at pin(10)
of P701 when a reel pulse has
been inputted?
of P701 when a reel pulse has
been inputted?
Check line between pin(92) of
IC701 and pin(10) of P701.
IC701 and pin(10) of P701.
Is the supply voltage of 12V fed
to pin(8) of P701?
to pin(8) of P701?
Is the voltage about 10V sent out
from IC on mechanism?
from IC on mechanism?
Check IC on mechanism.
Is the specified voltage applied at
the loading motor terminal?
the loading motor terminal?
Check line between IC on mechanism
and loading motor.
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.
42
VC-M305HM/LM
VC-M315HM/LM
FLOW CHART NO.13 DRUM MOTOR TROUBLESHOOTING(1)
The drum motor fails to run.
Is the voltage more than about 2.6V
DC given out of pin(30) of IC701?
DC given out of pin(30) of IC701?
Check IC701.
NO
NO
NO
YES
YES
Check PC 5V.
Is the supply voltage of 5V fed to
pin(3) of P701?
pin(3) of P701?
Is the voltage more than about 2.6V
DC given out of pin(12) of P701?
DC given out of pin(12) of P701?
Check line between pin(30) of
IC701 and pin(12) of IP701.
IC701 and pin(12) of IP701.
NO
YES
YES
Is the supply voltage of 12V fed
to pin(8) of P701?
to pin(8) of P701?
Replace drum motor.
Check M 12V line.
FLOW CHART NO.12 CAPSTAN MOTOR TROUBLESHOOTING
The capstan motor fails to run.
Is the voltage more than about 2.6V
DC given out of pin(29) of IC701?
DC given out of pin(29) of IC701?
Check IC701.
NO
NO
NO
NO
NO
YES
YES
YES
YES
Is the supply voltage of 5V fed to
pin(8) of P701?
pin(8) of P701?
Check PC 5V line.
Is the voltage more than 2.6V DC
sent in pin(9) of P701?
sent in pin(9) of P701?
Check line between the P701 and
pin(29) of IC701?
pin(29) of IC701?
Is the voltage of pin(5) of P701
1.6~2.7V?
1.6~2.7V?
Check line between the pin(91) of
IC701 and pin(5) of P701.
IC701 and pin(5) of P701.
Is the supply voltage of 12V/25V fed
to pin(2) of P701?
to pin(2) of P701?
YES
Replace capstan motor.
Check MOTOR Vcc line and motor
voltage selector circuit. (Q992, Q993)
voltage selector circuit. (Q992, Q993)
FLOW CHART NO.14 DRUM MOTOR TROUBLESHOOTING(2)
The drum motor runs only for a few seconds.
Replace IC on mechanism.
Check peripheral circuit of IC on
mechanism.
mechanism.
Is drum PG signal given out from
the pin(11) of P701?
the pin(11) of P701?
Is drum PG signal fed to pin(65)
of IC701?
of IC701?
Check line between pin(11) of
P701 and pin(65) of IC701.
P701 and pin(65) of IC701.
Is head switching pulse sent out
from the pin(23) of IC701?
from the pin(23) of IC701?
Check IC701.
Replace IC701.
NO
Check drum motor.
YES
YES
YES
YES
NO
NO
NO
D. FG-PG
about 5Vp-p
YES
NO
YES
YES
NO
NO
FLOW CHART NO.15 HEAD SWITCHING PULSE TROUBLESHOOTING.
No head switching pulse.
See FLOW CHART NO.13, 14
(DRUM MOTOR
TROUBLESHOOTING(1), (2))
(DRUM MOTOR
TROUBLESHOOTING(1), (2))
Is the drum motor rotating?
Is the drum PG signal and drum
FG signal present on pin(65) of
IC701?
FG signal present on pin(65) of
IC701?
Replace IC701.
Check line between P701 and IC701.
Check peripheral circuit of
IC on mechanism.
IC on mechanism.
Are the drum PG signal and drum
FG signal present on pin(11) of
P701?
FG signal present on pin(11) of
P701?