Commodore 1571 - Page 42

1571/C128D ALIGNMENT/REPAIR TEST
VERSION 1.2.1
CHECK FOR ALTERNATING DATA LINES --- INPUT HEX CODE 'AA'
NOTE: HEX 'AA' DATA LOOKS EXACTLY THE SAME AS HEX '55' DATA
DATA BUS
DISPLAY
CHECK IC
PINS
EXPECTED
SIGNAL
SCOPE
MODE
INCORRECT SIGNAL
PROBABLE FAILURE
10101010
10101010
10101010
10101010
10101010
U104 - 2,4,6,8
U104 - 3,5,7,9
U105 - 35
U113 - 8
Ulll - 6
LOW
HIGH
SERIAL DATA
SERIAL DATA
SERIAL DATA
DC
DC
DC
DC
DC
U104 - U105
U104 - U105
U105 - U113 - Ulll
U113 - Ulll
Ulll - U108
DATA BUS
DISPLAY
CHECK
CONNECTOR
EXPECTED
SIGNAL
SCOPE
MODE
INCORRECT SIGNAL
PROBABLE FAILURE
10101010 j CN12 - 1,9 | ANALOG DATA | AC | U108 - BAD DRIVE
CHECK FOR DOUBLING DATA LINES
---- INPUT HEX CODE '66'
NOTE: HEX '66' DATA IS DIRECTLY INVERSE TO HEX '99' DATA
DATA BUS
DISPLAY
CHECK IC
PINS
EXPECTED
SIGNAL
SCOPE
MODE
INCORRECT SIGNAL
PROBABLE FAILURE
01100110
01100110
01100110
01100110
01100110
U104 - 2,5,6,9
U104 - 3,4,7,8
U105 - 35
U113 - 8
Ulll - 6
LOW
HIGH
SERIAL DATA
SERIAL DATA
SERIAL DATA
DC
DC
DC
DC
DC
U104 - U105
U104 - U105
U105 - U113 - Ulll
U113 - Ulll
Ulll - U108
DATA BUS
DISPLAY
CHECK
CONNECTOR
EXPECTED
SIGNAL
SCOPE 1 INCORRECT SIGNAL
MODE | PROBABLE FAILURE
01100110 | CN12 - 1,9 | ANALOG DATA | AC | U108 - BAD DRIVE
CHECK FOR DOUBLING DATA LINES
--- INPUT HEX CODE '99'
NOTE: HEX '99' DATA IS DIRECTLY INVERSE TO HEX '66' DATA
DATA BUS
DISPLAY
CHECK IC
PINS
EXPECTED 1 SCOPE
SIGNAL 1 MODE
INCORRECT SIGNAL
PROBABLE FAILURE
10011001
10011001
10011001
10011001
10011001
U104 - 2,5,6,9
U104 - 3,4,7,8
U105 - 35
U113 - 8
Ulll - 6
LOW
HIGH
SERIAL DATA
SERIAL DATA
SERIAL DATA
DC
DC
DC
DC
DC
U104 - U105
U104 - U105
U105 - U113 - Ulll
U113 - Ulll
Ulll - U108
DATA BUS
DISPLAY
CHECK
CONNECTOR
EXPECTED
SIGNAL
SCOPE
MODE
INCORRECT SIGNAL
PROBABLE FAILURE
| 10011001 | CN12 - 1,9 | ANALOG DATA | AC |
+
------------- +----------------+ --------------- + -------- +.
U108 - BAD DRIVE
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