HP PL4260N Service Manual page 229

(1) The power of the signal generator should be turned on before turning on the power of DC power
supply.
(2) The voltage of DC power supply, in standard of Module input voltage, should be preset as below.
(Vs: 195V, Va: 60V)
(3) The power of power supply must turned on by this sequence. Reverse direction When turning off.
* Module on : 5V Va
(4) Signal generator should be selected with 1366 x 768 mode.
<Caution>
Vs, * Module off : Va Vs
(Fig. 1) Connection diagram of measuring instrument
5V