Duty Cycle span (at 5%)
Set: Duty Cycle = 5.0%.
Scope: Set main timebase to 20µs/cm and delayed timebase to 1µs/cm. Adjust delay so both
edges of low pulse are visible on delayed trace.
Adjust: VR11 for pulse low width of 5 divisions (between 50% point of the edges).
(Note: Watch the front panel reading and adjust Duty Cycle control as required.)
Duty Cycle span (at 95%)
Set: Duty Cycle = 95.0%.
Scope: Switch scope to other trigger polarity. Adjust delay so both edges of high pulse are
visible.
Check: Pulse duration is 4.7 to 5.3 divisions (between 50% point of the transitions). If not,
small compromise adjustments of VR20 and VR11 may be necessary.
Slew Rate Generator
Note: Because of the permitted tolerance on slew rate, these adjustments are unlikely to need re-
setting unless IC16 or an associated component has been replaced.
They require a scope with delayed timebase, and standard rise-time graticule markings; slew rates are
measured between the 10% and 90% points of the transition.
Connect: Scope to DMD (TP3-c) and 0V (TP3-d)
Set: Control = Transient; Slow Start = off; Enable = off.
Meters = Freq & Duty. Freq Range = Hi, Freq = 3kHz; Duty = 50%;
Meters = Level A & B. Mode = 80A, Level A = Max. (81.9) and Level B = 0.
Meters = Slew & Dropout. Slew Rate = Max. (fully CW);
Enable = on (the red light after mode switching below does not matter).
Set Hi range (current mode) slew rate
Set: Freq Range = Hi, Slew Range = Hi. The Slew Rate display should show about
2557 A/ms.
Scope: Set Y scale to 200mV/cm and main timebase to 50µs/cm. Adjust scope Y variable gain
and position to set top and bottom of waveform on 0% and 100% graticules.
Enable delayed timebase, set to 5µs/cm, check that there is no trace separation setting
shifting the waveform.
Adjust the delay to view the rising transition and look at the distance along the X axis
(time) between it crossing the 10% and 90% graticules.
Adjust: VR4 for 5.1 cm (horizontally) (= 25.6µs).
Set Hi range (other modes) slew rate
Set: Mode = 80V. The Slew Rate display should show about 819 V/ms.
Scope: Set delayed timebase to 20µs/cm.
Adjust: VR1 for 4.0 cm (= 80µs)
Set Mid range (current mode) slew rate
Set:
Freq Range = Mid, Slew Range = Mid, Mode = 80A.
The Slew Rate display should show about 81.9 A/ms.
Scope: Set main timebase to 1ms/cm and delayed timebase to 200µs/cm.
Adjust: VR5 for 4.0 cm (= 800µs)
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