u213-13
BLANK I NG
4.00
V/div
2.50 V 2.0
us/div
96.00 us
1
nr
IL
u
//I
II
SK193
Figure 9-4. Expanded Blanking Waveforms
Display Jumbled or Trace Off Screen
See function blocks D and I of A2 Controller Schematic Diagram (sheet 1 of 4) in the
Component-Level Information binder.
The two line generators are identical circuits, so the following steps apply to both; references
will be to the X generator with Y references in parentheses.
1. The voltage at
A2U202B pin 7 should measure 10.0 V.
2. Perform steps 1 through 5 of “Line Generators”
in this chapter. If the X POS and Y POS
waveforms look different from those illustrated in Figure 9-2, check the waveforms at the
low-pass filter’s input (function block E).
3. The waveform at the low-pass filter should look like X POS in Figure 9-2 but have an
amplitude from 0 V to
+5
V.
4. If the waveform in step 3 is incorrect, set an oscilloscope to the following settings:
Amplitude Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
V/div
Sweep Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
20ps/div
Triggering
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..External
5. Trigger the oscilloscope on the signal at
U207
pin 8 (LBRIGHT).
6. Compare the line-generator input signals at the following test points with those illustrated
in Figure 9-5. INTEGRATE and SAMPLE waveforms are replicas of VECTOR except for
polarity and amplitude. LCHAR is low when characters are drawn.
INTEGRATE:
Q202’s
collector
SAMPLE:
Q201’s
collector
LCHAR:
U207
pin 9
VECTOR:
U213 Pin 9
Controller Section 9-7
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