SONY BVM-D24 black screen issue

[nicolascarre000]

Hi, I don't know if someone can help me, but I have an issue with my BVM-D24.

When I display a black screen (screen on without any source for example), the screen is not perfectly black on the edges, with a slight blue tint. We can also see bars crossing the screen in diagonal.

Spoiler

I couldn't find a setting to fix this.

Thanks for helping me.

[nissling]

This is a design issue caused by a load in the flyback and was documented by Sony themselves.

To fix this you must adjust one of the two focus pots. Simply remove the top and you will find it on the left side, right next to the rear (see the white circle on the rather poor image below). When you adjust the focus you will find that one of them causes the blue tint to become more intense. Change it clockwise or counter-clockwise respectively and it should discharge. You'll hear a clicking sound and the tint will be gone.

Spoiler

The lines you see are meant to be in the overscan area as they're used to compensate for colors and white balance during warm up. Right after powering on, it's fully normal that they're visible and crossing the screen like in your picture but it should not be visible afterwards. Let me know if they persist after you've adjusted the focus.

[nicolascarre000]

Alredy thanks for your help.

I'm not sure, of what pots you are talking about, I took some pics

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Spoiler

Are these the ones you are talking about ?
And which one I have to adjust ?

[nissling]

Yes, those are the right pots. One of them adjusts vertical focus and the other horizontal. Don't remember which one so just try them. They are glued from factory so be a bit careful.

I suggest displaying a cross hatch pattern to make it easier to set the focus. It's on channel 95 on the CRT (put in 095 and then Enter on the control board).

[nicolascarre000]

After trying diferent adjustement, I was able to reduce a lot the blue tint.
But there is still a small glowing white on the border, and I can see also the lines, but this is very sligth to seeing that, I need to be in the total dark, and display a total black sreen.
I never heard a clicking sound as you said.
If I tried to turn a bit more the pots, I begin to lost the focus, so I don't think I can do something better with this.

If you have any other tips, I hear you.

Again thanks for helping me !

[nissling]

If the blues are changing while adjusting the focus, the charge is the issue.

Like I said you should turn it in the direction that makes it more intense, not less visible, for it to discharge. I think I had to turn it back and forth between min and max a few times until it discharged. After that your blacks should be clean.

[nicolascarre000]

Oh, I didn't understand this, so, do I have to stay a certain time with more intense blue tint to discharge before getting back it or just turn it back and forth between min and max a few times quickly ?

[nicolascarre000]

I tried to let it in the more intense position, but the blue keep to be be more intense. And now if I turn it back, the cross patern disapear during the transition, and reapear imadiatly.

I realy don't know if I do the right manipulation ?

[nissling]

It's supposed to discharge when you've moved it to its maximum position. I've only done this on one of the D24 I've worked on in the past.

I found a Reddit thread with some better explaination on this than I wrote haha.
https://www.reddit.com/r/crtgaming/comm ... vmd24_and/

[tongshadow]

Surely sounds like a tube problem, so in the long run it might be a good idea to invest on a Tube Rejuvenator.

Also considering the tube is similar to the FW900's, which is infamous for having tube issues, then I guess these Sony widescreen monitor tubes have engineering/manufacturing problems.

[nissling]

This is more a design flaw in the electronics than a failing tube. If you disable the blue gun you will still see the blue tint, making it obvious that it's just a charge which won't go away.

[tongshadow]

It might be semantics but whatever happens inside the tube, including the electron gun assembly itself, can be considered a tube issue. The service bulletin even states the cause is that barium, the element that coats the cathodes for electron emisson, becomes lodged in the G2 Grid. The procedure seems to be meant to cause high voltage arcing between the focus grid (G3) and G2 to blow away the barium particle.
I'm actually surprised Sony didnt recommend the use of CRT Analyzers/Rejuvenators as a solution on such expensive hardware.

[nicolascarre000]

I followed the instructions you provided me with the link, I think I got the same result of the guy, I did the adjustements, looking good but not perfect, I waited the next day, and now I don't see a glowing white, and I dan't any more the diagonal lines at all.

A big thanks, you are an expert man !!!