Commodore 1571 - Page 39

1571/C128D ALIGNMENT/REPAIR TEST
VERSION 1.2.1
H----------------------------------------------------------------------------------------------------- h
I 1571 DATA BUS WRITE CHART |
+ — — - — — — — - — — — - — — — - — — — — — — +
I CHECK FOR DATA LINES HELD HIGH
--- INPUT HEX CODE '00' I
+
+
+
+
DATA BUS
DISPLAY
CHECK IC
PINS
EXPECTED
SIGNAL
SCOPE 1 INCORRECT SIGNAL
MODE | PROBABLE FAILURE
00000000
U4 - 2,3,4,5
LOW DC
VO
D
1
D
6,7,8,9
00000000
U6 - 37
LOW DC
U6 - U14
00000000
U6 - 38
HIGH DC
U6 - U14
00000000
U7 - 9
LOW
DC
U14 - U7
00000000
U7 - 10
HIGH DC
U14 - U7
00000000
U7 - 6
0 V ANALOG
AC
U7 - CR3 - CR4
BAD DRIVE
00000000
00
1
D
0 V ANALOG
AC
U7 - CR7 - CR8
BAD DRIVE
CHECK FOR DATA LINES HELD LOW
--- INPUT HEX CODE 'FF’
NOTE: HEX 'FF' DATA IS APPROXIMENTLY DOUBLE HEX '55' DATA
+
----------- + --------------- +--------------+ ------- +--------------------------+
DATA BUS
DISPLAY
CHECK IC
PINS
EXPECTED
SIGNAL
SCOPE
MODE
INCORRECT SIGNAL
PROBABLE FAILURE
11111111
U4 - 2,3,4,5
HIGH DC
U4 - U6
6,7,8,9
11111111
U6 - 37,38
SERIAL DATA
DC
U6 - U14
11111111
U7 - 9,10
SERIAL DATA
DC
U14 - U7
11111111
U7 - 6
ANALOG DATA AC
U7 - CR3 - CR4
BAD DRIVE
11111111
U7 - 8
ANALOG DATA AC
U7 - CR7 - CR8
BAD DRIVE
CHECK FOR ALTERNATING DATA LINES
-- INPUT HEX CODE '55'
NOTE: HEX '55' DATA IS APPROXIMENTLY HALF OF HEX 'FF' DATA
+
------------ + ---------------- + --------------- + -------- + ---------------------------- +
DATA BUS
DISPLAY
CHECK IC
PINS
EXPECTED
SIGNAL
SCOPE
MODE
INCORRECT SIGNAL
PROBABLE FAILURE
01010101
U4 - 2,4,6,8
HIGH DC
U4 - U6
01010101
U4 - 3,5,7,9
LOW
DC
U4 - U6
01010101
U6 - 37,38
SERIAL DATA DC
U6 - U14
01010101
U7 - 9,10
SERIAL DATA DC
U14 - U7
01010101
U7 - 6
ANALOG DATA
AC
U7 - CR3 - CR4
01010101
U7 - 8
ANALOG DATA
AC
BAD DRIVE
U7 - CR7 - CR8
BAD DRIVE
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