Atari CX 5200 Field Service Manual page 68

Snowy Screen Troubleshootin g (cont.)
Yes
Does Pin II of U29(A26)
toggle each time 52
is pressed?
No
*
Does Pin 6 of U29(A26) go
high when 52 is pressed
and low when it is
released?
No
Check for possib Ie
shorts or opens on
the failing pin or
defective 52.
*U29 is chip designation
on
PCB HCAO 18087
is chip designation
A26
on
PCB IICA020 1 08
CX5200 Field Service Manual
*
10
Is Pin of U29(A26) at
OV?
Yes
4-11
QIO
Replace
Repair trace.
* * *NOTE***
If you are servicing a unit containing
PCB CA020 108, chip designators have
been changed from to A.
U
Open trace or
defective resistor
or capaci tor in
circuitry.