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Commodore 1701 - Improper Horizontal or Vertical Synchronization

Commodore 1701
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Improper
horizontal
or
vertical synchronization
NOTE:
1701
and
1702
locations are
the
same.
[Cause]
1) Defective horizontal and vertical sync:
The sync separator and amplifier consists
of
an
IC(lC201). The main cause
of
failure is
often
a failure
of
the
IC
itself.
It
is also necessary
to
be
careful
of
a possible failure
of
the
external
components. Because
the
change
of
voltage
at
each pin
of
the
IC
is extremely small,
it
is very
difficult
to
discover a failed element
by
measuring voltage.
2) Defective horizontal sync:
This is due
to
a failure
of
IC501
or
the
horizontal AFC
circuit.
3)
Defective vertical sync:
This is due
to
a failure
of
either
the
separator and amplifier
for
the
vertical synchronous signal,
or the vertical oscillator IC501 and
its
peripheral elements.
START
8.8V
R le201
NO
pin
8?
YES
NO
9V
at
IC201
C201
short
pin 9 ?
R106
open
IC201
faulty
YES
C202
short
R201 open
IC201
C211
short
faulty
22

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