Second one I've come across where the standby lamp thinks it is a lighthouse ( for a short while). When cooled down the neon's now black internal dropper , 1/3W or so, measured 550R . The switch housing says "110V lamp", surely I'm not the only one to have come across this arson issue. I don't have the schematic for the 150 , the BV120 schematic has the neon on the HT ac side, not the rectified and smoothed side. I've not taken the amp apart to explore wiring but have not found a dropper additional to the internal neon set for USA 110V mains wiring purposes. What is the work around , separate neon ala Marshall valve amps etc.
While at it, I suspect (not examined yet but suspiciously bright) that the mains-on neon is also set for 110V like the other BV150H . I'm in 240V land and that will need accommodating as well. This one 2003 manufacture and without attention, that dropper will go pyrotechnic in ten more years of use also