TM
11-5835-243-34/EE641-AA-MMl-010/E154
MTT/TO
31S3-4-110-1
c. Write Reset.
cartridge TW-433/UYH-5. Close and lock access
(1) Depress REWIND switch on exerciser.
door. Depress REWIND switch on exerciser. Wait
for BOT status.
When tape transport reports BOT status, depress
(2) Set WRITE switch on exerciser off.
RUN FORWARD switch on exerciser.
(3) Connect oscilloscope to TP5 on digital
(2) Depress and hold WRITE RESET switch on
read/write circuit card A2.
exerciser while observing signal at TP1, TP2, and
(4) Depress RUN FORWARD switch on
TP3 of digital read/write circuit cards A1, A2, and
exerciser.
A3, in turn.
(5) Monitor A2, TP5, triggering oscilloscope on
(3) Set oscilloscope to 0.1v/cm and verify that
signal observed at each test point is broadband
positive-going edge of the input signal. Verify that
noise less than 0.5v peak-to-peak maximum.
nominal period for one complete cycle of square-
wave signal observed is approximately 111
(4) Depress REWIND switch on exerciser.
microseconds.
Wait for BOT.
b. Instantaneous Speed Variation (Jitter).
3-12. Read Test
(1) With oscilloscope at TP5 on digital
read/write circuit card A2, oscilloscope time base
a. Read Data Bits.
such that one full cycle of the signal being displayed
(1) Depress WRITE DATA ALL PAT switch
on exerciser. Depress RUN FORWARD switch.
occupies 10 major divisions of the screen.
(2) Switch horizontal display control to x10
NOTE
MAG. (Each major division of the screen now
WRITE DATA ALL PAT causes the
represents one percent of the total signal period.)
WRITE DATA bits to toggle between
(3) Use HORIZONTAL POSITION control to
logic one and zero states in a binary
position left-most jittered positive-going edge of the
progression according to bit number (i.e.,
signal to the center of the reticle. Measure width (in
bit 1 toggles at the data rate, bit 2 toggles
divisions) of the jittered signal.
at 1/2 the data rate, and so on). The parity
(4) Verify that jitter does not exceed five
bit frequency will not be discemable.
divisions.
(2) Using oscilloscope, observe signals at each
c. Long-Term Speed Variation (LSV).
of READ DATA test points on exerciser.
(1) Measure the frequency of the signal at TP5
(3) Verify that bit 0 toggles each 50
on digital read/write circuit card A2 using frequency
microseconds, bit 1 each 100 microseconds, bit 2
counter set on 1-kHz scale. Set display rate such
each 200 microseconds, " etc. Allow tape to be
that the frequency is sampled every 10 seconds.
recorded to EOT.
(2) Record three consecutive readings and
b. Read Strobe.
compute their average (Favg).
(1) When tape transport reports BOT status,
(3) Verify that Favg does not exceed 9 kHz
depress RUN FORWARD and WRITE DATA ALL
270 Hz.
1 switches.
(4) Repeat steps (1) through (3) for RUN
(2) Using oscilloscope, observe STROBE signal
REVERSE.
at READ DATA CLK test point on exerciser.
(5) Repeat steps (1) and (2) above for FAST
(3) Verify that signal is a negative-going pulse
RUN FORWARD and FAST RUN REVERSE.
having a duration of 2.0 1.0 microseconds at 50%
Verify that Favg does not exceed 18 kHz 540 Hz.
amplitude points.
(4) Using frequency counter, measure
3-14. Start/Stop Time Test
frequency of READ DATA CLK. Verify that the
a. Start Time.
frequency is 20.0 0.6 kHz.
(1) Ensure that FAST switch on exerciser is off.
(5) Depress STOP and RUN REVERSE
Remove skew tape cartridge and insert a write
switches on exerciser. Repeat steps (2) and (3).
enabled standard cartridge.
(6) Depress STOP, FAST, and RUN FOR-
(2) Set oscilloscope to trigger on the negative
WARD switches on exerciser. Repeat steps (2) and
going edge of signal present at TP3 on servo control
(3).
circuit card A5 when RUN FORWARD switch on
(7) Depress STOP and RUN REVERSE
exerciser is depressed.
switches on exerciser. Repeat steps (2) and (3).
(3) Display signal present at A5, TP5. Adjust
signal amplitude on oscilloscope so that it is five
3-13. Tape Speed Test
divisions Peak-to-peak.
a. Normal Speed.
(4) Measure period from start of sweep to where
(1) Replace standard cartridge with skew tape
3-6
