I have replaced the HOT transistor & the flyback transformer but I still have only 160 volts screen voltage even with the screen adjustment on the flyback all the way up.Also with a high voltage probe Im only getting 28K volts & its a 32inch screen.
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Re: Picture is to dark
On the CRT PCB, there is a ceramic capacitor attached to the screen voltage circuit. Disconnect it and the voltage may come up. If it does, replace it. check your 200 volt line and see where it is, also.
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The horizontal output transistor that drives the flyback transformer overheats now. There might be other reasons too for this fault. If the flyback transformer has any internal winding short, this transistor will overheat. Just replace the horizontal output transistor. Check its heat. If the newly replaced transistor too overheats, replace the flyback transformer.
this is hardware problem - replace flyback transformer & big transisitor fixed near flyback (replacing these two parts is compulsory ) - also check all small size transistors ( 6 to 10 transistors will be there on main board - see picture ) - below shown picture is only to get an idea as how these parts looks like & roughly where they are situated on main board ... that means this picture is not that of your monitor's main board - in your monitor there will slight difference & also that bigsize transistor's number will be different ....... for more details about flyback transformer check this link http://www.fixya.com/support/t10123898-panasonic_ct_36hl43g_tv_just_turned
You have to replace the flyback transformer of your monitor. Its a high voltage stepup tansformer which provides necessory volteges for the picture tube like Anode voltage, screen voltage and focus voltage. After some years of use the insulation stength of the flyback transformer will become bad and the high voltage will try to discharge trough the nearest ground poit. At that time you will hear the sprking sound. Its because of the high voltage Anode volt is discharing to the ground it will reflect on the screen. Using the monitor in this condition will result in the failure of horizontal driver transistor and even the power supply. Replacing the flybalck will solve your problem.
Along with the flyback transofrmer, its horizontal output transistor also must be replaced. I don't know whether you have replaced it or not. If not, replace it too. It can be located very near to the flyback transformer, a three terminal component, black in colour, usually screwed to a metal heatsink. Then switch on the TV and measure the video output voltage at the video output card pluged directly to the picture tube neck. The collector of the video aoutput transistors must come around 145VDC. If it also is there, advance the screen control on the flyback transformer to get a raster. If that voltage is not there, it means that the flyback transformer is not working, and horizontal oscillator stage should be checked for oscillation, check the lined drive transformer for its primary winding open, Check the entire horizontal oscillator section. The collector point of the line drive transistor, the transistor that drives the line drive transformer, a small transformer soldered diretly to the printed circuit board; should be checked with frequency meter. The frequency at that point should come around 15525HZ approx: OK.
This sounds like low screen voltage(A1)try adjusting the a1 voltage bottom control on flyback transformer if you have a voltmeter, voltage on crt base possible market screen or A1 shoud be beteen 350/500 volts when making adjustment remember to take into account current taken by meter If voaltage will not adjust flyback transformer will have to replaced
This usually is indicative of the EXTREMELY HIGH VOLTAGE anode connection somewhere between the flyback transformer and one or more of the crt picture tubes or the splitter. Being that this circuit has a running voltage potential of over 30,000 volts if you are not familiar with these YOU CAN BE KILLED messing with it!!! What happens is that there is a breakdown of insulation over time usually from dirt or other environmental contamination. Usually a good cleaning and replacing the HV anode wire that has failed. (hint) it will be the one that the "ticking noise" is coming from. The ticking noise is actually the high voltage arcing to the chassis/ground.
my first instinct in this is flyback transformer. or if it is three tube projector could be a high voltage splitter lines in picture sound like what is called retrace lines ... this is another indication of a possible bad flyback. high pitch sound is another sypmpton of a high voltage flyback transformer problem. WARNING televisions generate potental lethal charge. the device called flyback is used to generate several THOSAND volts. so be carefull if you take the back of any television. along with the flyback the horizontal output transistor possible could have failed. What type of tv is it? model
There is no "Flyback transformer" in the LCD monitor "Benq 17" model No. Q7T3". Such a component, a "Flyback transformer" is found in televisions and in Picture Tube type monitors. The red wire of a "Flyback transformer" is where 27,000 VOLTS comes out of to connect to the picture and such a voltage IS DEADLY so never enter a TV or computer monitor unless you know exactly what you're doing. To bring your hand too close to the "Flyback transformer" is to GET ZAPPED, you don't even have to TOUCH that transformer or the Red Wire that comes out of it!!!!
As far as a fuse blowing, NEVER PUT IN A FUSE WITH A HIGHER AMPERAGE RATING: it's there to protect certain components from being permanently damaged. If the fuse is blowing you must find out "why". There's got to be a short circuit in one or more components. Transistors, Diodes and Capacitors are easy to check for shorts. Transistors, Diodes are usually what short out. There's not much more I can say here.
A schematic diagram that shows the voltage on the many components of a running LCD circuit is what you need to find out where volatges should be. If a voltage is missing you must find out where the problem stems from. There are other ways to test circuitry, with an oscillascope and a schematic diagram that shows test points and the wave pattern that's suppose to be present.