Cats Eye Alignment Check And Adjustment; Ce Alignment Ctieck; Isv Pulse Pattern - Tandon TM-100-1 Operating And Service Manual

2.1.2.4 Observe the following pattern (see Figure 2-3).
-
8.0 USEC
-
_ _ .
1
~
480 NSEC MAXIMUM
Figure 2-3
ISV Pulse Pattern
2.1.2.5 Measure the amount of jitter present on the leading edge of the third pulse (see Figure 2-3). The lead-
ing edge of the third pulse should start 8 usec ± 240 nsec from the trigger pulse. Jitter on the third
pulse of greater than ± 240 nsec (480 nsec edge-to-edge) indicates excessive ISV.
2.1.2.6 Confirm the measurement (see Section 2.1.2.5) with a second work diskette.
2.1.2.7 If the ISV is excessive, replace the drive belt (see Section 5.1 ), and remeasure the Instantaneous
Speed Variation (ISV) (see Section 2.1.2) .
2.1.2.8 If the ISV is excessive, replace the drive motor (see Section 5.10), and remeasure the ISV (see Sec-
tion 2.1.2).
2.1.2.9 If replacing the drive belt and the drive motor does not cure the excessive ISV, see Section IV
(Troubleshooting Guide).
2.2 CATS EYE ALIGNMENT CHECK AND ADJUSTMENT
The Cats Eye (CE) alignment procedure locates the magnetic read/write head at the proper radial distance from
the hub center line, thus ensuring that the track location is accurate (see Figure 2-4). This adjustment is neces-
sary only after service or if diskette interchange problems are suspected.
2.2.1 CE Alignment Ch.eek
2.2.1 .1 Set up a dual-channel, wideband oscilloscope, as follows :
Channel A: Test Point 1
Channel B: Test Point 2
Ground: Test Point 10
Read Differentially: A plus B, B inverted
Time Base : 20 msec Per Division
External Trigger: Test Point 7, Positive Edge
2-3