Anyone here any good at fixing TVs?

by ballistic 21 Replies latest jw friends

  • JH

    I used to love Sony TV,s until they came out with Sony Wega's......

    The picture is so hard on the eyes now, the black is too black and the whites are too white.

  • The Lone Ranger
    The Lone Ranger

    I am a TV Tech. Without seeing the Faulty, you might be lucky enought to adjust it out. Open the back and look at the EHT, there should be 2 pots on it, one is for the Focus and the other is the screen voltage, the screen voltage seems to be too high, turn the pot down a bit, the picture will get a bit darker but the lines should disappear if this doesn't work then it could be caused by a faulty Vertical Amp. If all this seems strange to you then for God's sake don't touch it at all, you'll only hurt yourself.

  • ballistic

    Thanks Lone Ranger. That seems quite along the lines of what I read on another site:

    25.13) Red, green, or blue retrace lines

    Where only one color is showing, suspect an incorrectly adjusted individual background/bias control or bad part on the CRT neck board for that color. * Individual brightness/background/bias control(s) - mark setting of pot for the problem color and then see if a slight adjustment removes the retrace lines. See the chapter: "TV Adjustments". Of course, if this happened suddenly, the problem is not due to a misadjusted control though a dirty pot is possible - turn it back and forth - this might clean it and restore normal operation. * Component or connection on CRT neck board - insufficient voltage to or incorrect biasing of the video driver for this color can result in the CRT never totally blanking. Compare voltages and signals, and swap components between good and bad channels to confirm. * Blanking circuit - this may be a part of the video/chroma chip or separate. Check and compare waveforms of good and bad colors to determine if the blanking pulses are making it to the video output. There is a slight possibility that a bad CRT may result in visible retrace lines. To eliminate this possibility: * Disconnect the filament - all evidence of a picture, raster, and retrace lines should disappear once the filaments/cathodes have cooled (15 seconds or so. If there are still visible retrace lines, the CRT is suffering from cold or field emission from someplace (may not even be the cathode). * Turn down the screen (G2) control on the flyback (usually). If one color remains no matter how you set the control, again there is some kind of weird emission from the CRT. However, if white/gray retrace lines remain, the problem may be in the screen supply. 
  • ballistic

    "along the lines" no pun intended!

  • dmouse

    Same fault on both TVs? Did you use the same scart lead?

    I had no end of probs with poor TV image once that went away when I bought a good quality scart lead.

  • CyrusThePersian

    Hi! Since the problem appears to be only at the top of the screen, it is unlikely to be an improperly set screen /bias control. The more likely problem would be a bad electrolytic capacitor in the vertical circuit, as alluded to by the Lone Ranger above. It should be a relatively inexpensive fix. Don't attempt it yourself, take it to a qualified service tech. CyrusThePersian P.S. The fact that you have two sets with the same problem isn't all that weird. This is a fairly common problem.

  • Dismembered
    Re: Anyone here any good at fixing TVs?

    I threw an air conditioner down a flight of stairs once. It made a hissing noise, and after that it wouldn't cool the air anymore. I became flumoxed.

    Send me your Sony, I'll check it out


  • moshe

    I've worked on TV's and replaced picture tubes, too- back when they were mostly tubes and not solid sate- sorry.

  • The Lone Ranger
    The Lone Ranger

    tell me how you went. Try turning down the indivial colors on the neck board, if nothing seems clear to you, you can take a photo of the rear of the TV and email it to me, I'll then be able to help you better.

  • ballistic

    Thanks for your help. I haven't started to look at it yet. On one TV the lines are about 3 quarters down the screen, the other TV is just the top quarter. To be honest, having read a load of web sites I'm now petrified of getting a shock. Should normal screw drivers provide sufficient insulation from the anode voltage when it is un-plugged? Also, the first TV has a problem with the picture fading out which I think is the tube heaters. Is it safe to re-solder connections from the tube heaters?

Share this