loaded to death interseting story of crt monitor repair

hi i am wael fathe electronics technician from libya i will share with you my repair story despite the fact that it was on crt but any way electronics is electronics and we may apply it one lcd .....let get started a friend of mine brought me a monitor that has power but no display (no EHT HIGH TENSION ) he said he sent it to many technicians and they all fail in repairing it when i opened the cover i could see nothing wrong little scan to dry joints reveals nothing another indepth scan for dry joints and nothing ..so i put my meter (trusty fluke i love it ) on voltage scale
and measure all the outputs all votages are there 12 volt 24 and the 35 volt all ok
but the 5 volt source which is derived from the 12 volt is strage it is 4 only i was confused why that line is alittle low ? is there component shorted and drag it low?? but if there actuay a shorted component it would have drag it down dwon the 4 volt until complete shut down occur hmmmm ok let me measure the resistance between the ground and the 5 volt source it is around one kilo or little less it should be more higher what this semi shorted component hmmm i am determind to find it from my experience the 5 volt source is going to several chips for example it goes to micro processor eprom video pre amplifier video amplifier etc etc how i narrow down the problem ? ok divide and conquere ...i can pull the conector that goes to the crt neckboard that is carrying the 5 volt supply and see if my short disappear
yessssssss it did the 5 volt back to normal when i seperate the connector that goes to the neck board and when i press the monitor on i can hear the cracking of the high voltage tension build up things are getting interesting now all i have to do is to know which component in the neckboard that is shorted and replace it as quick action i desoldered the vcc pin of both the amplifier ic and the preamplifer ic and get the connection back press on pffffffffff nothing happen? i am sure one of components is shorted and that what cause the 5 volt to back when i disconnect the 5 volt line ok i am determind ..all legs of both ices desoldered and upon desoldering each one i press the power to see at which pin i get my 5 volt back it is at one of the pins in the preamplifeir ic of color when i ( lm12something was the number ) desoldered it...the 5 volt back and the monitor work when i reconnect it 5 disappear quickly to the internet to see what is this pin i find that the pin is data pin ...this are digital montorsi and the ices communicate with the processor which tell them to allow more color intensity brightness etc all depend on the values already stored at the eeprom this pin use a pull up resistor when the data ic wante to data to be low he shorted the pin to ground
when he want the data to be high he just release the short and the pin will back to high
as the pin is connected trough a on kilo resistor to the 5 volt source when the ic fail in such way that its data pin get shorted to ground we have then one kilo
resistance from 5 volt source to ground which pulled the source partially to 4 volts the processor was not happy to work with it even if every thing work we will never have a display because lm12something is video preamplifier with out it we get no picture when i replace this ic the monitor works like newwwwwwww