Sharp 13VT-CL10, Service Manual, Page: 43 / 106

43
13VT
-L200
TROUBLESHOOTING OF VCR SECTION
Check/replace X7701
and/or IC7701.
ELECTRICAL TROUBLESHOOTING
VCR POWER TROUBLESHOOTING
FLOW CHART NO.1-1
The VCR is dead.(No power)
Unplug the AC power cord.
Replug it a few minutes later.
Are the AT 5V and AT 12V
lines normal?
Are the AT 5V and GND
lines properly connected
with IC7701?
Is there oscillation
(16MHz) at pins (38) and
(39) of IC7701?
Does the "L" pulse of sys-
con reset appear at pin
(43) of IC7701 after the
AC cord is plugged in?
Does pin (21) of IC7701
change from "L" to "H"
level when the power
button is pressed to turn
on the power?
Are the PC 9V and PC 5V
lines normal?
Check power circuit.
Check poor soldering.
Check the signal line of
sys-con reset all the way
up to pin (22) of IC2001.
Check the power key
input to IC2001 and serial
datas/clocks between
IC2001 and IC7701.
Check power circuit.
Check the sensor inputs
to IC7701 from
mechanism. (CAM
switches,start/end
sensors,and reel sensors)
KEY-IN TROUBLESHOOTING
FLOW CHART NO.1-2
Key-in input for VCR is not received.
Is the key switch in good
contact?
Is there short-circuit in the
key input?
Are signals received at
pin (27) of IC2001 when
the key is activated?
Check IC7701, IC2001 and
signal line of serial datas,
serial clock and ready (L).
Check the switch contact.
Check IC2001 and switches
for poor soldering.
Check key lines to input
IC2001.
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
NO