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.

3 . 0 0 V/di v 0 . 0 0 v 1 . 0 0 ms/dlv 0 . 0 0 0 s

xPOS

Y POS

z POS

t

B L A N K 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