Hi Naftali,
Are you using the LM96551 or the LM96550 pulser? If you are using the LM96551, the +/-40V is built it already. If you are using the LM96550, please use the power up sequence on page 10 of the LM96550 datasheet. http://www.ti.com/lit/ds/snas504f/snas504f.pdf