Tandy CM-8 User Manual

Circuits Checked:
• Video circuit and its
related
circuits
NO PICTURE
Note : If the picture does not appear,
fully rotate the brightness contrast con-
trol clockwise before inspecting.
Check the video
signal at the TP451 with an
oscilloscope. Is a video signal present?
No
Yes
Check the video
signal at the base of 0851 with
an oscilloscope. Is a video signal present?
No
Check the video
input circuit and
its related circuits.
Check 0402 and
its related circuits.
,- --1
I 0401
I 0402
1
0405 I
L ___ _J
Circuits checked:
• IC601 and its related circuits.
NO SYNCHRONIZATION
IC601, IC481
Check
0851
and its related
c
ircuits .
1
0851-
1
1
0404 I
L _ __ _J
Input cable
in
put socket
computer
IC451
Both horizontal and vertical
synchronization cannot be
obtained.
NO HORIZONTAL SYNCHRONIZATION
(But vertical synchroni-
zation is normal .)
Does pin Q3' of IC601 have a saw-
tooth wav e and sync signal?
r- -.,
I IC601 I
: R605 I
I R606 I
1
R607 I
L - - _J
r- -..,
: IC601:
L - - _J
With the H- hold control adjusted,
does the
horizontal sync frequency
vary?
r- - _,
I C606 I
I C604 I
L __ J
No
1
1c6o1,
I R620 :
I R607
I
I IC481 I
L - - _J
NO VERTICAL SYNCHRONIZATION
(But horizontal synchronization
is normal.)
Vertical sync adjustment is not
possible at all.
r----
: IC601
-- - --,
I
R514 C5041
L _________ -1
22
The vertical sync frequency can be
varied slightly .
r- - -- - - -
...,
I
IC601
R513
I
R510 R514
I
R51 1 C503
I
I
R512 C505
L _ - -
- - -
_J

Tandy CM-8 Specifications

General

Brand	Tandy
Model	CM-8
Category	Monitor
Language	English