Atari CX - Page 71

Pot Control Line Troubleshooting(Cont.)
I
L J
Swapout
1) U5
2) U7
4
If you are servicing a unit containing
PCB CA020108, chip designators have
I
Lhec~ the voltages on '
Ql 1414 and compare
Can +CAV be adjusted
now?
i
I readings to the ones
shown for the
"A" I
yes
been changed from u to A.
condition in the
Put unit into Port Test
node but do not put in
Port board (loop
back
board).
I
I
Defective component
in Pokey Adjust
circuitry.
I
Are the readings
correct?
J
No , Replace rransistor. Does Pokey Adjust -
pass?
I
Condition/ Ql 1 Ql2 Ql3 Q14
Transistor A B A A A 0
Emitter
13V
13V 3.2V
OV
0 0
3.2V OV
Base
12V
13V
4V
OV
0 .7V
3.
' OV
Cdlector
4-6.4V
OV 13V
13V
3.SV
OV
12V 13V
I
Check the voltages on
Q11 -QL 4 and compare
readings to the ones
shown for the
"B"
condition on the
CX 5200 Field Service Manual
Repair
No
Yes
chart
below.
Are the readings
I
yes Check for opens &
correct? -
shorts in circuitry Jc -
repair.
A