1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Old TV picture adjustment advice please

Discussion in 'Televisions' started by Rave, Aug 18, 2004.

  1. Rave

    Rave
    Standard Member

    Joined:
    Aug 18, 2004
    Messages:
    9
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Ratings:
    +0
    Hi,

    A couple of weeks ago I pulled a Sony KV2900 out of a skip. It's quite a nice looking 29" TV, I'm guessing a few generations earlier than the KV-29F5U (?) I bought in '98. Anyway, the picture was a bit poor when I got it going, but with a bit of tweaking of the row of little pots at the back of one of the main boards I've got it as close to centred as it'll go and got rid of most of the pincushion distortion etc. although I think it's too far out of spec now to be fixed entirely through tweaking. Still, it's only going to go in the bedroom anyway as a second TV.

    The main problem now is that although the picture is the right shape and in pretty much the right place, the picture itself is rather distorted. The problem is that the scan lines in the middle of the picture are given a lot more space than the lines at the top and bottom, so people look stretched while titles etc. at the bottom of the screen look badly squashed. There were two adjustments that I didn't tweak for fear of electrocuting myself reaching then (they're out of the way)- one was labeled 'h-phase' and the other doesn't seem to have a label, but it's a large pot on the board that's actually attached to the back of the tube. Are either of those what I need?

    There's another pot on the back-of-the-tube board labelled 'h-stat'. I brief tweak later I discovered that it seems to adjust the focus, so I set it as sharp as possible. I then discovered that on another board is another large pot which is actually labeled focus! What's the difference?

    Finally, from a safety perspective I have been being very careful and working with one arm behind my back where possible. What parts of the TV actually present a high voltage danger when it's switched on? I've just kept well away from everything pretty much :) .

    Thanks in advance for your help.

    Rich :¬)
     
  2. Rave

    Rave
    Standard Member

    Joined:
    Aug 18, 2004
    Messages:
    9
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Ratings:
    +0
    Bump?

    From some further research, I apparently need to adjust the vertical linearity to correct for the adjustments I've made to vertical size. Just gotta find out where that is now....

    Rich :¬)
     
  3. red16v

    red16v
    Active Member

    Joined:
    Aug 20, 2004
    Messages:
    552
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    18
    Ratings:
    +5
    Focus is exactly what it says 'on the tin' - focus. Adjust it for maximum sharpness if you don't have access to a signal generator. HSTAT is 'horizontal static' convergence. It's the first 'tweek' that the service engineer would perform on a newly fitted crt. It adjusts the convergence of the RGB electron beams in the centre of the crt - if you think about it in the centre of the crt the electron beam in not being deflected up/down or left/right ie, the electron beam is STATIC. Having set it to be correct in the centre of the screen then a service engineer would proceed with the rest of the convergence of the RGB beams over the rest of the picture. If you tweeked it then the RGB beams would seperate over the entire width of the picture - tweeking it for maximum sharpness (as you did without a test signal) would be a good 'second guess' if you had to. H-phase - a technical term for horizontal picture position. The other large pot you found on the PCB on the rear of the CRT is most likely the tweek for 'A1 volts' - don't touch it ! IT sets what is called the 'beam cut off' for the CRT. Too far advanced and you will see 'flyback lines' across the picture. too far in the other direction and everything will be very black crushed. Good luck, yt.
     
  4. Rave

    Rave
    Standard Member

    Joined:
    Aug 18, 2004
    Messages:
    9
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Ratings:
    +0
    Hey, thanks for the advice, and sorry for the delayed reply. The TV fixing project has been put on the back burner for the last couple of weeks and I forgot to check back and see if anyone had replied. I guess I know what all the mystery controls are now, but I'm still no closer to finding the control for vertical linearity :( . I'll try and have another poke about later, to see if I can find it.

    Rich :¬)
     

Share This Page

Loading...