Commodore 1571 - Page 34

1571/C128D ALIGNMENT/REPAIR TEST
VERSION 1.2.1
* SIGNALS FROM ADVANCED CHART 2 MUST BE MEASURED WHILE ONE OF THE KEYS,
(+) OR (-), IS BEING HELD DOWN AND THE READ/WRITE HEAD IS STEPPING
+
-------------------------------------------------------------------------------------- +
1571 STEPPER MOTOR CONTROL LOGIC — ADVANCED CHART 2
***** INCORRECT STEPPER MOTOR SIGNAL FROM BASIC CHART 2 *****
+
--------------- +--------------------------------------------- + ----------------------- +
CHECK IC
EXPECTED
INCORRECT SIGNAL
PINS
SIGNAL
PROBABLE FAILURE
U13 - 4
0 VDC LEVEL WITH +5 VDC LEVELPBOESf
U(D13— UQ22
U16 - 13
0 VDC LEVEL WITH +5 VDC LEVEL PULSE
U22 - U16
U16 - 12
+12 VDC LEVEL WITH 0 VDC LEVEL PULSE
U16 - Ql
CHECK
EXPECTED
INCORRECT SIGNAL
CONNECTOR
SIGNAL
PROBABLE FAILURE
+----------------+---------------------------------------------+
----------------------- +
| CN5 - PIN 1 | +5 VDC LEVEL WITH +12 VDC LEVEL PULSE] Ql - CR10 - DRIVE |
+ -------------- +-----------------------------------------+ --------------------- +
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