HP 8560E Service Manual page 630

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
on page
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 CRT +110 VDC ON LED on the rear panel 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 W1. The A2
assembly distributes this +5 V to the A17 CRT driver through W7.
A17 sends +5 V back to A6 as the HV SHUT_DOWN signal on W8.
As a result, A2, A17, W1, W7, and W8 must all be in place for the
high-voltage supplies to operate.
5. If all of the power supply indicators along the outside edge of the A2
controller assembly are lit, the A6 power supply is probably working
properly.
Figure 12-6 Probe Power Socket
Chapter 12
629.
Display/Power Supply Section
Blank Display
Figure 12-6
629