Tv rca model rar tf 2921, with sound and black screen.-
Measure the tension at each cathode. In the pins of the Zocalo. KR - KG-KB.
The rest was asked by the colleague.
Well people there take the relevant measurements. The resistance R432 measured and is fine. Take the voltage on pins KR 162 V, KG 171 V and KB 127 V. On leg 10 of the Fly Black it gives me 214 I go, but on leg 9 I have no voltage. On the screen part of the socket I have 214 V.
is very low the screen in the socket of the tube .... turn the potentiometer q, it is in the lower wall of the flo-bak to the right and see if the voltage increases to about 350v ... you are sure that the R432 well ... the R432 is connected x one side at 14v q, they leave the fli-bak..C432 ... the other end of the R432 is connected to the collector of the Q402 ... the emitter of the Q402 goes to pin9 abl of the fli-bak..verify that ... put the digital voltmeter on the 1000v scale to measure the screen ... ok ..
as it is, you have 214v on leg 10 of the fli-bak and 214v on the screen ... measure again ... measure on the positive of the C443 and see that there is voltage ... then on the 1000v scale it measures the screen in the socket of the had ... with 214v on the screen will not illuminate the screen x that voltage is very low ... it should reach a minimum at 350-400v .. check if you have no prob, with the tension of the screen ...
In leg 10 of the Fly Black I have 128 V, in the positive of the C443 I have 210V. I measured the resistance and it's fine. And in the part where the screen goes I have 210 V. I raised and lowered the potentiometer and the current did not change. Consultation may not be that the flay back is not sending high voltage and has some of the turns in short so I have the rest of the voltages except that.
the voltage of the screen in the tube must be a minimum of 350-400v ... with 210v of screen it will not illuminate the screen ... I don't know if it is taking the screen voltage well ... but if it is that volatje it can have the damaged fli-bak ... highlight the screen cable in the socket of the tube q, it comes from the fli-bak and measures it outside on the 1000vdc scale and measure q, voltage gives ...
Ready, I measure it like this, check what precautions I have to take out the flay back and how I can do to know if any expiration is not short.
There is the screen disconnected from the tube socket, it gives me 210 volts. Precautions to remove the flay back and how do I check if it is damaged.
the cable of the screen q, comes out of the fli-bak is the finest red .... if with the cable outside the socket it gives you 210v that screen does not give the necessary voltage ... you have turned the potentiometer of the screen to the maximum. .he gives you the same ... try it ... in which scale is taking the voltage of the screen ... see if you have another fli.bak there like that to prove ... ok ..
if you are going to replace the fli-bak you have to q, discharge the voltage of AT into the pacifier of the tube ... that is done by taking a long screwdriver and with a cable with two clamps on each tip ... a clamp goes to the metal of the screwdriver ... the other clamp is connected to the mesh cable q, it is around the tube q, it is ground ... the screwdriver is taken by the handle and isroduced under the pacifier until the spark is felt ... there is q, repeat operation 3o4 times x reloads only again ... ok ...
Totally black screen, turn on the filaments, I connect cable entry and listen to the channel but I have no image.
Well, the flayback brings three reds, the thickest that sends the 20,000 volts, the medium that goes to the filaments of the tube and the FINEST THAT IS THE SCREEN, THIS LAST (FINEER) IS THE ONE THAT DESOLDS FROM THE PLATQUET THAT GOES BEHIND THE TUBE AND MEASURING IT HAS 500 VOLT.
well that's the screen ... if 500v is fine the fli-bak ... now look where that cable was welded in the socket of the tube must have a high voltage capacitor welded between the screen and ground ... remove it and re-solder the screen cable where it was welded ... and measure again q. voltage is there with the cable placed in the socket of the tube ... ok ..
Well I took the capacitor and I was still doing the same, I did not have the 450-500 volts of the screen. Disconnect the tab that supplies the voltage for the KG-kr-KB terminals, and if there is voltage on the screen, I re-soldered the capacitor and the voltage remains. But I connect the card and I have no more voltage. I have an electrolytic capacitor of 250 volts per 10 microfarads, which is on the plate of the tube is listed as C 504. Will that be short?
I turn on the TV with the card disconnected from the plate that goes to the socket of the tube, and I take a reading of the voltage that I feed to the kg-kr-kb terminals, and I have a voltage of 230 volts, but when I connect it the voltage of the escreen I get goes.
you can have prob, with the tube ... try another tube to get out of doubt ... it doesn't matter if it's smaller ... the important thing is that the yoke and the socket of the tube are good ... if with another tube the same thing can be prob, from fli-bak ... ok
Thanks a lot for the contributions, I managed to find the problem, a tiny cut on a track did not let the current flow. Thank you very much for your valuable time.
Hi Gustavo2578 ... I'm glad that you already have the TV running ... from me "congratulations" on the achievement ... and don't forget to value my contributions as (solution) ... in the space of my first comment ... in this way it remains in the archive of solutions for other colleagues .... until another opportunity .... greetings!
