HP D8906A - Uszkodzenie Q708 i ZD702, przyczyna przegrzania R778?

witam !
hi all colleagues
i have this monitor HP Model : D8906A which is built on LG Chassis CA-78 and i have the service manual for this monitor .
this monitor has a separated Horizontal scan and EHT stages , the EHT based on IC 703 = STR-S6824 does any one has a datasheet for this IC?
the horizontal stage using Q708 = 2SC5411 which is short circuit and the B+ regulator Flyback topology ( +180V) and as seen in the attached picture i have ZD702 short circuit i don't know exactly the zener voltag but sounds a +18V zener and resistor R778 which is 7.5 Ohm /5W ceramic resistor , this resistor got over heated and a part of it's ceramic body is broken but the resistor itself still intact and didn't open !!
the mosfet used here Q709 = 2SJ306 is also intact , neither short nor open !!
what may be the cause this ?
is that a problem with excessive B+? or just the HOT got shorted causing that?
any help or hint is highly appreciated .
thanks in advance
Kind Regards

hi techs
i've got a strange thing here , the schematic diagram indicates that the HOT is Q708 = 2SC5411 which is 1500/600V , 14A , 60W
but actually when i get the shorted one out i found it's :
2SC5589 which is 1500/750V , 18A , 200W !!
i couldn't find this transistor or an equivalent and the best i could get here was : 2SC5301 which is 1500/800V , 20A , 120W
i've replaced Q708 = 2SC5589 with 2SC5301 and replaced the shorted zener diode and started the monitor and got nothing .
well , now i have the 6.3V heater voltage is drop to 3V , this comes from IC906 = PQ6RD083 made by sharp , which is faulty , this is a switchable low power-loss voltage regulator which i can't find here , is there any way to overcome this problem?
also , the replaced HOT 2SC5301 is getting very hot , what's the best replacement for transistor 2SC5589?
thanks for any help
Kind Regards

Hi all
well, this monitor really sucks and got many probelms inside :
first the heater 6.3V is not down to 3.3V and when i lift IC906 = PQ6RD083 a switchable low power-loss voltage regulator i got 12V at the imput of this IC which come from D906 and C910, while fitting it loads the output to be 6V only , this IC isn't available here so i've use a normal 7806 regulator for testing and got the heater lit but getting no video with black screen .
now i have a problem with video output , i've changed the video output IC303 = LM2435 and got the screen lit but no data ( blank) , i don't also have OSD , so i suspect the video processor now IC302=M52743 .. i'm i right? or what else could cause this?
i think this monitor will be beyond economical repair
any help or hint is highly appreciated
thanks in advance
Kind Regards