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VCR POWER TROUBLESHOOTING
The VCR is dead. (No power)
Is the fuse F701 alright in the power ND
SW PWB ?
Are the AT 12V and AT8.5V lines
normal in the MAIN PWB ?
YES
NO
Is the AT 5V line normal ?
YES
N O
Are the AT 5V and GND lines
properly connected with IC7701 ?
YES
Is there oscillation at pins (38) and
YES
Does pin (43) of IC7701 change from
plugged in or/when the RESET
button is pressed and then released ?
J
YES
Does pin (21) of IC7701 change from
button is pressed to turn the power
on ?
Check wire harness to mechanism
and the sensor inputs to IC7701 from
I
FLOWCHART NO. l-l
7
Replace the fuse.
Check fuse resistor and transistor
Does pin (5) of lC7702 go to "H" level
Check the AT 5V line, lC9902 and
(about 1.8V) when the cassete tape
is inserted ?
I
Check poor soldering.
Check and replace the loading motor
Check the signal line of sys-con reset
all the way up to pin (55) of ICl 001.
Check power key input to ICl 001
and serial dataslclocks between
,
Check Q9911,09912, and Q9917.
CASSETTE CONTROL TROUBLESHOOTING
A cassette tape is not taken in.
YES
I
Does the start sensor cover become
open when the cassette tape is
inserted ?
YES
Does the start sensor pin (2) of
N O
cassette tape is inserted ?
YES
I
Does pin (2) of lC7702 go to about
N O
inserted ?
Is the correct voltage at the loading
A cassette tape is taken in, but ejected at once.
I
Does start sensor pulse at pin (2) of
when the cassette tape is loaded ?
YES
Does end sensor pulse at pin (3) of
ND
when the cassette tape is loaded ?
Do the cam switches A and B
operate normally when the cassette
tape is loaded ? (at pins (100) and
FLOWCHART NO. 1-2
Fix or replace the cassette housing.
I
I
Check the start sensor cover.
Check the start sensor and the way
up to pin (2) of IC 7701.
Check pin (12) of IC7701 and all the
way up to pin (5) of lC7702.
I
Check 167702 and AT1 2V line.
FLOWCHART NO. l-3
Check the start sensor and all the
Check the end sensor and all the
Check cam switches and all the way
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