IBM 3274 51C Maintenance Information page 266

Test Line
Test
Points
Names
Points
TH01
Diff Read B
TPA01
TH02
No Pin
TPA02
TH03
Diff Read A
TPA03
TH04
-High Gain
TPA04
TH05 -Disable Stepper Motor
TPA05
TH06 +14V
TPA06
TH07 Access Clamp Voltage
TPA07
. THOS
Oscillator
TPAOS
TPA09
TPA10
TPB01
TPB02
TPB03
TPB04
TPB05
TPB06
Figure F-20. 51 TO Control Card Cable
F.3 Maintenance
F.3.1 Collet/Flat Spring Assembly
F.3.1.1 Collet/Flat Spring Removal (Figure F-21)
1. Power down.
2. Turn the operator knob
G
to the closed position.
Warning: Do not attempt to remove the collet/flat spring
Gbefore removing the bail
o.
Too much pressure or
binding can damage the spring.
3. Loosen the lever screw
0 .
4. Push the bail
0
inward slightly and disconnect the
bail actuator cable eyelet
0
from the lever
8 .
F-22
Line
Test Line
Names
Points Names
MC-3 TPB07 01 PTX
MC-1 TPC01 +Access 0
MC-2 TPC02 +Inner Tracks
MC-O
TPC03 -5V dc
Ground
TPD01 +Access 1
+Erase Gate
TPD02 +Switch Filter
Ground
TPE01 +Index
-Head Load
TPF01 +Diskette Sense
+5V dc
TPG01
+Write Erase Enabled
02 PTX
TPH01 +File Data
+24V dc
TPLD2
D2 LED Voltage
Ground
TPLD1
D1 LED Voltage
+Select Head 1
TPAMP2 Preamp TP2
+Write Gate
TPAMP1 Preamp TP1
+Head Engage
TPCTO Center Tap Head 0
Write Data
TPCT1 Center Tap Head 1
5. Turn the operator knob
0
to the open position.
6. Loosen the bail mounting screw
G .
7. Observe the position of the bail return spring
CD ;
then remove the bail pivot rod
G,
the bail return
spring
CD '
and the bail
0
by sliding the bail
0
out from under the head load arm
e.
Warning: Ensure that the heads do not hit each other when
the bail
0
is removed from under the head load arm.
S. Remove the screw and nut
G
from the collet
actuator rod
e .
9. Remove the operator knob
G.
10. Remove the collet actuator roll
CD
and the pressure
roll
CD.
11. Turn the collet actuator rod
e
up and out of the
way. Then remove the collet/flat spring assembly
G.