a 0 0 v/dIv 0 . 0 0 v

1 0 . 0 us/div

0 . 0 0 0 s

U201A-1

T P 2

U203A- 1

TPI

S K 1 9 7

Figure 9-8. Normal X/Y Line Generator Waveforms

Intensity

1.The length of the vector being drawn can effect intensity (U210A, U21OC, and U2lOD). Refer to “Long Lines Dimmer Than Short Lines” in this chapter.

2.Short A2U207 pin 2 to pin 7. If the display does not brighten, troubleshoot LBRIGHT switch, U207B. This switch intensifies trace A and active softkeys.

3.Short A2U207 pin 2 to pin 3. If the display does not darken, troubleshoot DEFl switch, U207A. This switch is used in analog zero-span.

4.Change the intensity (under [DISPLAY)). If the intensity does not change, troubleshoot the intensity DAC, A2U212A. (A2U212A is controlled from the front panel.) The amplitude of the waveform at U211A pin 1 should increase or decrease with intensity changes.

5.Clamp U211B limits the voltage to about 4.2 V. Short A2J201-1 to ground and set the intensity DAC to a number greater than 80. A major portion of the waveform should be limited to 4.2 V.

6.Troubleshoot the maximum brightness clamp, A2U211C.

Bad Characters or Graticule

If the displayed characters are bad but the graticule is correct (or if the symptoms are reversed), troubleshoot the X- and Y- generator switches A2U207D and A2U207C. Check that the switch driver signal LCHAR is working properly. Refer to “Display Jumbled or Trace Off Screen” in this chapter.

9-10 Controller Section