Commodore 1571 - Page 33

1571/C128D ALIGNMENT/REPAIR TEST
VERSION 1.2.1
*****
1571 STEPPER MOTOR CONTROL LOGIC
INCORRECT STP 0 OR STP 1 SIGNALS
*****
— ADVANCED CHART 1
FROM BASIC CHART 1
— +
----------------------
INCORRECT SIGNAL
PROBABLE FAILURE
STP 0
DISPLAY
STP 1
DISPLAY
CHECK
PINS
IC EXPECTED
SIGNAL
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
U4
U4
U13
U7
U7
U7
U7
U7
U7
10
11
3
23
30
29
31
25,28
24,27
0 VDC
0 VDC
+5 VDC
0 VDC
0 VDC
+1 VDC
+1 VDC
0 VDC
+5 VDC
U4
U4
U13
U6
U13
U6
U8
07
07
U13
U13
U6
U7
U7
U7
U7
U17
U14 - U8
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
U4 - 10
U4 - 11
U13 - 3
U7 - 23
U7 - 30
U7 - 29
U7 - 31
U7 - 25,28
U7 - 24,27
0 VDC
+5 VDC
0 VDC
+1 VDC
+1 VDC
0 VDC
0 VDC
+5 VDC
0 VDC
U4 - U13 - U17
U4 - U13 - U14 - U8
U13 - U6
U6 - U7
U13 - U7
U6 - U7
U8 - U7
U7
U7
1
0
U4 - 10
+5 VDC
U4 - U13 - U17
1
0 U4 - 11
0 VDC
U4 - U13 - U14 - U8
1
0 U13 - 3
0 VDC
U13 - U6
1
0 U7 - 23
+1 VDC
U6 - U7
1
0
U7 - 30
0 VDC U13 - U7
1
0
U7 - 29
0 VDC
U6 - U7
1
0
U7 - 31
+1 VDC
U8 - U7
1 0
U7 - 24,25
0 VDC
U7
1
0
U7 - 27,28
+5 VDC
U7
1
1
U4 - 10
+5 VDC
U4 - U13 - U17
1
1
U4 - 11 +5 VDC
U4 - U13 - U14 - U8
1
1
U13 - 3
+5 VDC U13 - U6
1
1
U7 - 23
0 VDC
U6 - U7
1
1
U7 - 30
+5 VDC
U13 - U7
1
1
U7 - 29
+5 VDC
U6 - U7
1
1
U7 - 31
0 VDC
U8 - U7
1
1
U7 - 24,25
+5 VDC U7
1
1
U7 - 27,28
0 VDC
U7
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