5. Compare the signals at the following test points with those illustrated in Figure 9-2.
X
POS:
A2J202 pin 14
Y POS:
A2J202 pin 3
Z OUT: A2J201 pin 3
BLANKING: A2J202 pin 15
Note
Waveforms displayed on an analog scope may show considerably more spikes.
This is normal and is due to the wider displayed bandwidth.
6. Troubleshoot the circuits associated with any bad waveforms.
x
POS
3.00
V/di
v 0.00 v
1.00
ms/dlv
0.000
s
Y
POS
z
POS
t
BLANK
I
biG
t
SK191
Figure 9-2. Line Generator Output Waveforms
Blanking
See function block J of A2 Controller Schematic Diagram (sheet 1 of 4) in the
Component-Level Information binder.
1. Using an oscilloscope, check for blanking pulses at
A2J202 pin 15. A2U206 pin 6 should be
at a TTL high. Blanking pulses turn the CRT beam off during the sample time of the line
generators and when moving the CRT beam to a new position for drawing the next vector.
2. Set an oscilloscope to the following settings:
Amplitude Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.4
V/div
Amplitude Offset
. . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . .
+2.5
V
Sweep Time . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . 20
ps/div
Triggering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..External
3. Externally trigger the oscilloscope off the signal at
A2U207 pin 8 (LBRIGHT).
Controller Section 9-5
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