IBM Selectric

DOG CLUTCH PAWL AND RATCHET CHECK
The distance in time between the teeth of the dog clutch rat-
chet is 14 ms. Normal operational cycles will vary in time
- depending. on where the clutch pawl enters the clutch ratchet.
This variation, however, should never exceed 14 ms.
more
var s or ratchets.
Figure 30.6
Scope: Across resistor in series with magnet coi I.
Set OLSA to single cycle. Operate printer in short burst
with
the start pushbutton. Observe variati on of pu Ise length.
The example shows a-variation in pulse length of about 12 ms
for the eight printer cyc les recorded.
LOWER CASE MAGNET
•
I
I
,
I
•
I
1=
iI
I
•
•
-
-
-
•
Figure 30.7
Scope:
Time Base:
Across Resistor in
Series with Magnet Coil
10 ms/cm
Vert Amp:
2
volts/cm
Sync:
+ Int
Time from start of pick to feedback
Magnet seal time
C4 makes at 35°
Total Mechanical Delay
6.0 ms
12.5 ms
25.0 ms
1.8.5 ms
6.5 ms
U.C. MAGNET
Figur~ 30.8
Scope:
Across Resistor in Series with Magnet Coi I
Time Base:
Vert Amp:
Sync:
10
ms/cm
2
volts/cm
+ Int
Time from start of pick to feedback
Magnet seal time
C3 makes at 35°
Total Mechanical Delay
MACHINE SPEED CHECK
Figure 30.9
Machine Cycle = 65 ms
Scope:
C2 N/O Contact Point
Ref:
Power Supply Common
Time
Base: 10 ms/cm
10.0 ms
12.5 ms
28.0 ms
22.5 ms
5.5 ms
Vert Amp:
2
volts/division (with lOx attenuated probe)
Rise of
C2 N/O to next C2 N/O = One Machine Cycle
4-34