486 Chapter9
Controller Section
Analog Zero-Span Problems (8560E only)
Analog Zero-Span Problems (8560E only)
1. On the HP 8560E, press PRESET, SPAN, ZERO SPAN, SWEEP, 1, ms,
CAL, MORE, and CRT ADJ PATTERN.
2. Set an oscilloscope to the following settings:
Amplitude scale ......................................................... 10V/div
Sweep time ............................................................... 1ms/div
Triggering .................................................................External
3. Externally trigger the oscilloscope off the signal at A2U207 pin 8
(LBRIGHT).
4. The display should be similar to Figure 9-11 on page 486 except that
the untriggered trace should show at the left edge of the screen. In
these settings, DEF1 causes switching between the line generators
and the analog inputs (sweep and video). DEF1 remains high when
the CRT adjust pattern is on. Refer to function block M of the A2
controller schematic, 1 of 4.
5. The sweep input from J1-41 should go from 0 V to +10 V; the video In
signal should go from about 0 V to 1 V from the bottom to the top of
the screen. Apply a dc voltage to A2J4, Video In, to test the circuit.
6. In Figure 9-11 on page 486, there is no synchronization between
DEF1 and the video patterns X POS and Y POS when DEF1 is TTL
high. The Y POS level when DEF1 is low is the Video In level.
Figure 9-11 DEF1 Synchronization
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