Atari 2600 Field Service Manual page 119

2600A Defective I/O Lines Troubleshooting Procedure
Determine
which lines are
def
cctive by
referring
to
Figure b 7 .
Check the lines
indicated as
defective
for
-5v
at J202 or 1203
(See chart).
I
Defective ,4202
Cap.
Connecror
(RAM) Line No.
No.
Pin No.
15
C236 m n
k
14 C229 3202-Pin 3
I
Is
+5v
present
Swapout
I I
Does Diagnostic
Yes
on the
tinds)
L ) A202
Matrix
now look
Yes
just chcckec'"
corrccr
(see
Check the RAM
Repair
open trace
(A2021 pin. Is +5v
beween
A202 pin
p m m t theft?
shoned t o
+5v
and tht J20311203.
(Check trace l i n e s ) .
I
b
I
Arc them any-shorts?
I
-
I
Check tract
l i d s )
from
defecrive pinh)
for
h m to ground.
[5
~ 5 v
now
Yes
I
present
ar the
Repair
I
A202 pin?
I
I
Replace the
capacitor
on
that
line (see chart).
Docs the Diagnostic Swapout
Matrix screen
now 1) A200
look
correct
(see
Fig.
4-61
2 ) A201
2600/2600A Domestic VCS