4 . 0 0 V/div

2 . 5 0

V

2 . 0 us/div 9 6 . 0 0 u s

 

 

 

 

 

 

1 nr

 

 

 

 

 

 

I L

u

 

 

u213-13

B L A N K I N G

//I II

S K 1 9 3

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