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.
The high voltage transformer may be the problem, because it feeds back secondary voltages to different parts of the set, for example is the vertical deflection voltage present at the ic, if memory serves me there should be around 26volts, if it's missing it means the fuse is open or the flyback pin is not generating the voltage.
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.
From your description it is a high voltage problem, the cause is the fly-back transformer has failed, it generates the high voltage and with the help of other circuitry produces a picture. The cost to repair will be on the high side.
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
Hissing noise and picture on and off means faulty flyback transformer, it has a small crack and voltage is leaking out, replace the flyback, if tv still not working replace horizontal output transistor (broken flyback could blow the transistor).
Hello, The Horizontal Output transistor needs to be changed as it is most likely shorted. The current transistor on this set is a 2SD3402 (no longer available) it's new replacement part number is the 2SC5902. Order 2 2SC5902 Horiz Output transistors.Replace the transistor by it self once and if all is ok then fine. If not replace it again and also the the Flyback HV transformer. The HOT transistor is probably shorted again and the transformer is causing it.
When the horizontal output (2SC4927) is shorted it means one of 2 things is wrong - the horizontal drive transformer has cracked solder joints or the flyback transformer is shorted inside. If the solder joints on the horizontal drive transformer (the small grey transformer connected to the base of the horizontal output transistor) are cracked then the set will play for a little while and then the parts you just replaced will again be destroyed. ALWAYS resolder the driver transformer when replacing the parts you mentioned! When I replace the parts you mention and I do not see any obvious cracks on the driver transformer then I unsolder the B+ pin of the flyback (labeled 135, for 135 volts) and put a 60 to 100 watt lightbulb (drop-light) in series with the flyback. This means that the 135 volts B+ goes through the lightbulb and then into the flyback, so the lightbulb acts as a current limiter to protect the horizontal output. When you turn the set on the bulb should glow no more than about half bright and you should hear the high voltage come up, but you should not see a picture. If you turn the set on and the bulb glows as bright as if it was plugged into the wall then you can bet that flyback is shorted and must be replaced.