Here is the service manual
http://diagramasde.com/diagramas/otr...er_v173_sm.pdf
I see the brightness pin provides a PWM signal. Now strange thing if I remove that pin the inverter turns on quite fine. Both with controller sending the signal and with voltage applied manually by me (the pin removed from controller board). I am wondering. Could be some sort of coupling effect somewhere? Cause in theory I am removing that PWM signal. What would be voltage level and frequency of such signal? No scope at hand here. Also what would be cheapest way to generate that PWM? Maybe this
http://www.instructables.com/id/Yet-...rato/?ALLSTEPS . I am willing to do some tests. This is more than anything a learning thing. To gain experience. So lets say buying a 5 USD inverter at ebay would solve the thing but won't be too interesting.