9. Move the probe cable to A2J201, press SOFT KEY #l and wait five seconds.

16. Press SOFT KEY #4 . The results will be sent to the printer.

11.If a failure is indicated in any of these tests, the fault lies on the A2 Controller assembly. to obtain more information:

a.Press the down arrow key one less time than the test number. (For example, press it twice for the third test on the list.)

b.Press SOFT KEY 83 , then SOFT KEY #4, and when the printout is complete,

SOFT KEY #6.

12.If no failures were indicated in testing the A2 Controller, move the probe cable to A17J4.

13.Press SOFT KEY #I and wait five seconds.

14.Press SOFT KEY 84. The results will be sent to the printer.

15.If no failure is indicated in the printout, check the high-voltage supplies as described “High Voltage Supplies” in this chapter.

Blank Display

1.If the LED above the front-panel LINE switch is lit, most of the A6 Power Supply is functioning properly.

2.Carefully check the voltages on the front-panel PROBE POWER jack. Be careful to avoid shorting the pins together. See Figure 12-3.

3.Check that the fan is operating. If the PROBE POWER voltages are correct, and the fan is turning, the A6 Power Supply is probably working properly.

4.If the rear-panel’s CRT +llO VDC ON LED is lit, the high-voltage supplies should also be operating. (The high-voltage supplies will be turned off if the HV SHUT-DOWN line is low.) The A6 Power Supply feeds +5 V to the A2 Controller through WI. The A2 assembly distributes this +5 V to the Al7 CRT Driver through W7. Al7 sends +5 V back to A6 as the HV SHUT_DOWN signal over W8. As a result, A2, A17, Wl, W7, and W8 must all be in place for the high-voltage supplies to operate.

12-6 Display/Power Supply Section