Read Sharp VC-MH85 (serv.man4) Service Manual online
42
VC-MH705HM/LM
VC-MH815HM/LM,MH85HM
VC-MH715HM,MH835HM
FLOW CHART NO.7 KEY CONTROL TROUBLESHOOTING(2)
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.
and (89) of IC701, and the function
keys.
YES
NO
NO
YES
Key-in input is not received
<Except for jog shuttle mode
.>
FLOW CHART NO.8 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.
required.
Is the supply voltage of 5V fed to pin(2)
of RMC801?
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?
receiver when the infrared remote control
is activated?
Replace receiver.
Check between at pin(1) of receiver and
all the way up through to pin (4) of IC701.
all the way up through to pin (4) 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.9 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
pin (87) of IC701
Check line between pin (92) of IC701
and pin(10) of P701.
and pin(10) of P701.
Is the supply voltage of 12V fed to pin
(8) of P701?
(8) of P701?
Check M 12V lines.
Check IC on mechanism.
Check line between IC on mechanis
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?
loading motor terminal when the cassette
tape is inserted?
Does IC on mechanism output to about
10V when the cassette tape in inserted?
10V when the cassette tape in inserted?
Does pin(87) of IC701 change from"H"
to "L" level when the cassette tape is
inserted?
to "L" level when the cassette tape is
inserted?
Does the start sensor cover go to open
when the cassette tape is inserted?
when the cassette tape is inserted?
SWITC
FUNCTION
SWITC
FUNCTION
TERMINAL
Ref No. Ref No.
VOLTAGE
S805
SET
S801
POWER
0.000V
S806
CH(+)
S802
EJECT
0.652V
S807
TAPE SPEED / PAUSE
S803
MENU
1.250V / 1.864V
S808
PAUSE / REC
S804
CH(-)
1.864V / 2.561V
S883
REC / 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)
Does pin(10) of P701 go to a "H" level
when the cassette tape is inserted?
when the cassette tape is inserted?
YES
YES
YES
NO
NO
NO
FLOW CHART NO.6 POWER TROUBLESHOOTING(6)
In case of output voltage at low level.
Check peripheral circuits IC901, IC903,
C9336, R932, R930 and R933.
C9336, R932, R930 and R933.
The result of IC901, IC903, C9336, R932,R930 and
R933. Replace where necessary.
R933. Replace where necessary.
Check C901 and peripheral circuits of
IC901.
IC901.
Replace IC901.
Check short-circuit or leak of T901.
Replace T901.
Check primary circuit and peripheral
circuit of Q901 and Q902.
circuit of Q901 and Q902.
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