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Tube TVs
Sony KV27XBR55 TV without high voltage
Televisor SONY KV-27XBR51
Televisor SONY KV-27XBR51
3 Soluciones
11 Reparaciones
hace 5 años
hace 5 años
Good morning colleagues, they brought me this TV because it did not turn on, I repaired the ignition fault and it started very well, good sound good image, having it in test the image went away but the sound remains well, when checking I find all the voltages in the TRC socket but the high voltage of the display falls; My request for help is directed in the sense that before I blame the FBT definitely collaborate to me to know if there is any other cause for the FTB to malfunction and the high voltage of the screen falls. For your help I will be greatly grateful, see you later.
In this link is the diagram of that TV
https://www.electronica-pt.com/esquema/tv/sony-esquemas-tv/sony-kv-27xbr51-kv-27xbr55-chassis-anu1a-35230/Diagrama
9.700
hace 5 años
Friend if the high voltage (sucks that goes to the screen from the flyback) falls also should lower the other voltages in the flyback. Land each cathode to ground can be by depletion of one of these.
hace 5 años
Good morning friend Evelio, I did the suggested test and the three colors illuminate quite the same way, in addition, I separated the pacifier from the screen and tried to see if it takes out the high voltage but no current arc is formed
9.700
hace 5 años
Friend then it is not short but the high voltage circuit is open, I have to change the flyback
hace 5 años
Thank you very much Evelio, it is what I was afraid of but I did not want to leave just with my opinion, I do not know how to value your contribution to close this question, I think you should answer me as a proposed solution to be able to assess, you are very grateful, that have a good day, see you later
46.781
hace 5 años
If there were no HV in the RGB katodos test to earth, it would not illuminate each color.
What effects do you observe when increasing the SCREEN?
hace 5 años
Thanks Javier for answering, when you increase the screem you don't see any changes on the screen
46.781
hace 5 años
What voltage does SCREEN have in both minimum and maximum and set if it increases or decreases when the control is moved? .......
What voltage does the RGB power supply (180v / 200v) have?
9.700
hace 5 años
Javier the voltage for the cathodes goes from a secondary winding independent of the high one for the screen.
46.781
hace 5 años
If ... it leaves the FBT, it is usually filtered by a C between 10uf at 22uf / 250v
9.700
hace 5 años
Margarito on the ABL pin of the fly measured in diode function with the suck that reaches the screen, what size does it command?
9.700
hace 5 años
Javier if you look at the diagram, it may be that the fly is open internally for high voltage.
hace 5 años
Recognizing mistakes is wise attitude, I was wrong with the screem potentiometer, I was moving another, now answering the question, there are 200v for cathodes, in kr there are 198v; in kb there are 201, in kg there are 201v: I found the screem in 420v when the potentiometer goes up it reaches 784v and if it goes down, well now I have iamgen graduating the screem to 681v but return lines appear to me and a little gray the image
46.781
hace 5 años
Friend Evelio greetings, notice I have difficulties with access to the diagram I am working with a somewhat outdated tablet
9.700
hace 5 años
That indicates that the diagnosis was wrong, but calm when you make a mistake you learn more. Check the circuit of ABL R530, R560 and R561 how much it marks and what voltage has yen on pin 3 of IC531.
hace 5 años
In short, the flyback is working because the screen now has an image with delay lines and when the screem potentiometer is being manipulated, the image looks good for fractions of seconds.
46.781
hace 5 años
hace 5 años
Now that I see the image. Renew the filter capacitor of the 200v source (RGB) and place the SCREEN at the point where the image comes out smoothly
46.781
hace 5 años
Check the good condition of components in the ABL line that leaves the FBT especially all those high value R
hace 5 años
Good evening, fellow friends, I tell you that the TV is already working at one hundred, I reviewed all the elements related to the ABL circuit and I did not find any that was altered by what I dedicated to solving said circuit from the FBT terminal to the micro and Solved the fault, I appreciate your collaboration because without it I was still battling, again my thanks to Evelio and Javier
hace 5 años
Thanks Evelio, without your suggestions I could not have started the search for the solution
9.700
hace 5 años
As advice whenever a device arrives with a certain number of years of work, check the welds.
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