Read Sharp VC-M331HM (serv.man5) Service Manual online
37
VC-M321HM
VC-M331HM
VC-M331HM
7.
ELECTRICAL
TR
OUBLESHOO
TING
FLOW CHART NO.3 POWER TROUBLESHOOTING(3)
In case of abnormal noise(sound)
Check D9612, D9601, D9602,
D9603, D9604 and D9607.
The D9612, D9601, D9602, D9603,
D9604 and D9607 as a result of
check, if poor the replace.
NO
FLOW CHART NO.5 TIMER TROUBLESHOOTING (1)
The flourescent display tube fails light up.
Is the supply voltage of 5V fed to
pin(18) of IC801?
Check STBY 5V line.
Is the supply negative voltage of
-25V fed to pin(16) of IC801?
Check negative voltage line(STBY
-25V) and power circuit.
Is there 4MHz oscillation at
pins(19) and (20) of IC801?
Check FL801.
Is the filament voltage applied
between (1)/(2) and (31)/(32) of the
fluorescent display tube?
Also negative voltage applied
between these pins and GND.
Check power circuit and peripheral
circuit of D9910.
Does the fluorescent display tube
function?
Replace IC801.
Check for cracks on the fluorescent
display tube.
YES
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 R9611.
The IC901, IC9601, C9613, R9608,
R9609, R9610 and R9611 as a result
of check, if poor the replace.
Check IC901 and peripheral circuits
pin(9) of IC902.
Replace IC902.
Check short-circuit or leak of T901.
Replace T901.
Check primary circuit and peripheral
circuit of Q901.
FLOW CHART NO.1 POWER TROUBLESHOOTING(1)
No power
Unplug the AC power cord.
Replug it a few minutes later.
See FLOW CHART NO.2 POWER
TROUBLESHOOTING(2)
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
Is the fuse good?
Replace fuse.
Is AT 5V voltage line normal?
Check primary circuit.
Are AT 42V, AT 23V, AT 12.6V, AT -25V
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-FAIL (L) signal line etc.
Check system control circuit(IC701).
FLOW CHART NO.2 POWER TROUBLESHOOTING(2)
In case of Fuse(F901) blown out.
Replace F901, Q901, IC902 and
R904, check D910, D911, D912 and
D913 as a result of check, if poor,
replace at the same time.
Check short-circuit or leak of D9612,
D9601, D9602, D9603, D9604,
D9607 and secondary circuit.
38
VC-M321HM
VC-M331HM
VC-M331HM
CASSETTE
P801
TEST
P802
S807
MENU
S809
CH(+)
S811, 806
EJECT
S813
3.8V
SW 1/SW 2 INPUT VOLTAGE(V)
3.1V
2.5V
1.9V
1.2V
0.6V
POWER
S882
STOP
S883
PLAY
S884
PAUSE/STILL
S885
REC
S810
SET
S802, 808
CH(-)
FLOW CHART NO.6 TIMER TROUBLESHOOTING (2)
Does the key switch make good
contact, when the cassette tape is
inserted?
Check switch contact.
Is there a short in the scan outs or
key inputs?
Check all the terminals of IC801
and switches for poor soldering.
Are pulses received at pins(26) thru
(29) of IC801 when the keys are
activated?
Check lines of key in and scan out.
Check IC801, IC701 and FIP data,
FIP clock, FIP CS and key data.
YES
YES
NO
NO
NO
YES
Key-in input is not received
<For jog shuttle mode
.>
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
<Except for jog shuttle mode
.>
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
C813 of (+) side?
Check AT 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
Is the cassette housing distorted?
Fix or replace the cassette housing.
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(11) of IC702.
Is the supply voltage of 12V fed to
pin(13) of IC702?
Check M 12V lines.
Check IC702.
Check line between IC702 and
loading motor.
Replace loading motor.
Is the specified voltage applied at the
loading motor terminal when the
cassette tape is inserted?
Does pin(12) of IC702 change to
about 10V when the cassette tape in
inserted?
Does pin(11) of IC702 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?
39
VC-M321HM
VC-M331HM
VC-M331HM
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?
See FLOW CHART NO.12 CAPSTAN
MOTOR TROUBLESHOOTING
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(10) of
IC702 when a reel pulse has been
inputted?
Check line between pin(92) of IC701
and pin(10) of IC702.
Is the supply voltage of 12V fed to
pin(13) of IC702?
Is the voltage about 10V sent out
from pin(15) of IC702?
Check IC702.
Is the specified voltage applied at the
loading motor terminal?
Check line between IC702 and
loading motor.
Does the loading motor run?
Replace loading motor.
Replace cassette cam, gear, etc.
YES
YES
YES
Check M 12V lines.
NO
YES
NO
YES
YES
YES
NO
NO
NO
NO
NO
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 he cassette
tape is loaded?
Check line between cam switch and
IC701.
Replace IC701.
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
FLOW CHART NO.11 SYSTEM CONTROL TROUBLESHOOTING
No power is turned on.
Are key data pulses applied at
pin(15) of IC701, respectively?
Check IC801 and IC701, and all the
way thru between them.
Are FIP data pulses, FIP clock pulses and FIP control ready pulses applied to pins(25), (24),
(23) and (22) of IC801, respectively?
Does power control (H) signal at
pin(94) of IC701 change from "L" to
"H" level?
Check IC701.
Does the base voltage of Q9905
change from about 9.3V to 10V?
Check line between Q9905, Q9906
and IC701.
Is voltage of 9V sent out from the
emitter of Q9905 transistor?
Check peripheral circuit of Q9905
and AT 12.8V line.
YES
YES
YES
NO
NO
Does the base voltage of Q9908
change from about 5.5V to 6.2V?
Check line between emitter of Q9905
and base of Q9908.
Is voltage of 5V sent out from the
emitter of Q9908 transistor?
Check peripheral circuit of Q9908
and AT 5V line.
Check peripheral circuit for poor
soldering.
40
VC-M321HM
VC-M331HM
VC-M331HM
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(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/20V fed
to pin(5) of AC connector?
YES
Replace capstan motor.
Check MOTOR Vcc line and motor
voltage selector circuit.
(Q9903, 9904, 9909, 9910)
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(58) of IC701?
Check IC701.
NO
NO
NO
YES
YES
Check PC 5V and line and pin(9)
of IC701.
Is the supply voltage of 5V fed to
pins(25) and (2) of IC702?
Is the voltage more than about 2.6V
DC given out of pin(29) of IC702?
Check line between pin(58) of IC701
and pin(29) of IC702.
NO
YES
YES
Is the supply voltage of 12V fed to
pin(20) of IC702?
Replace drum motor.
Check M 12V line.
FLOW CHART NO.14 DRUM MOTOR TROUBLESHOOTING(2)
The drum motor runs only for a few seconds.
Replace IC702.
Check peripheral circuit of pins(4),
(5), (6) and (7) of IC702.
Is drum PG signal given out from the
pin(8) of IC702?
Is drum PG signal fed to pin(66) of
IC701?
Check line between pin(8) of IC702
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 CHART NO.13, 14
(DRUM MOTOR
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 IC702 and
IC701.
Check peripheral circuit of IC702.
Are the drum PG signal and drum
FG signal present on pins (8), (9)
of IC702?