Atari CX - Page 99

SOFTFIRE (TOP FIRE BUTTON) TROUBLESHOOTING
I
Be sure Pokey Adjust
Screen
is displayed.
If not, press key 5
and then
START.
L
I
L
When the top fire button
yes
Defective
is pressed does pin
1)
A7
16 of A7 show 5V p-p?
2)
A8
A 3) A2
I
Does output pin of
multiplexer pulse to
5V p-p when top fire
button is pressed?
(See Chart below)
Does input pin
go
Low when top fire
Defective
1) Cap
2) Port
3) Open Port to
Open output pin
to pin 16 of
A7.,
Yes Defective
I 1) Multiplexer
2) A7
Repair or Replace.
I
Multiplexer
Port
- Output & Pin Input Pins
1
A9 Pin 3 192,475
2 A10 Pin 13 1 1,12,14,15
Note: Some 5200
2-port boards have pins 1,8,9,10 and 11
of A7 jumpered together on the solder side of the
PCB. Future PCB's will incorporate this jumper.
Do not add
these jumpers to the 5200 2-port board.
CX5200 Field Service Manual
Changed by
ECN #0036
6/21 /83