Can I fix bulging on crt tv along horizonal edge in center?

[Brad251]

I checked out a Trinitron kv-27fs120 in person from Craigslist today and I tested it with Artemio's 240p test suite using my Wii. I ultimately wound up not getting the TV and noticed a few things wrong with the picture. The picture bulged out on the top horizontal edge in the center of the TV and it was very noticeable. I know a lot of geometry problems can be fixed in the service menu but in general, can this specific geometry problem be fixed in the service menu? Similarly, if there is bulging in the picture along either of the vertical edges, can this generally be fixed in the service menu?

There was also a whitish, bright, thin streak in the bottom left corner that I am not sure what it was. My first thought was that it could be burn in. What do you guys think that this was if it wasn't burn in?

I currently have a Trinitron kv-24fs100 and I will not be keeping it because it does not display dark parts of the picture well; especially grays. I have to jack up the brightness and contrast to max just to see the gray checkered background in Retroarch with my Wii. I have tried adjusted the gamma and messing with the service menu and screen knob but can't fix it. Otherwise, the picture looks great and I was hoping this Trinitron I checked out today wouldn't have this problem but it did. It was not quite to the same degree but I had to turn up the brightness and contrast to around 70% to make out detail well in dark/gray parts of the picture. I think this might be a problem with these particular models as a few other people with the same model TV in other forums have mentioned this same problem.

I don't think I will get anymore of the lower end Trinitrons and instead go with another brand. Maybe JVC, Panasonic, Phillips or Toshiba. I definitely want a non-HD CRT with component input but it doesn't have to be a flat CRT. I do hear that the Trinitron kv-xxfv310 is one of the best CRTs you can get and will likely pick it up if I can find one for cheap.

[Ed Oscuro]

I have the exact same model (kv-27fs120) and it has a dip along the bottom. Great geometry otherwise. I'd say that it might need a magnet, but look up all the service mode geometry settings to see if anything helps.

As for the thin streak in the bottom left corner...it reminds me a little of a little rainbow I get when turning my set on, near the bottom. With default overscan settings it didn't show, but it does appear at startup after I reduced overscan most of the way.

[accaris]

I answered all of these questions in your last CRT thread about the 24FS100, but here's another shot at it...

Both of the issues you describe can be caused by the deflection yoke being out of alignment, which can easily happen if the TV is bumped, set down too hard, or even just sitting there over time due to gravity.

The horizontal bowing can be caused if the yoke is at a bad angle and the splotch in the corner could be burn-in or magnetization, but it could also be the beam hitting the screen the wrong way (again, yoke out of alignment.)

To fix, you take the back off the TV, loosen the screw on the neck of the tube, and physically move the deflection yoke around (forward/back left/right) until it looks right. There will probably be 2 to 4 rubber feet that look like door stoppers glued to the chassis that are supposed to prevent the yoke from slipping; you can detach these and move them around to secure the yoke if you need to.

Don't do any of this if you're nervous about working around high voltages.

P.S.: Most flat tube Trinitrons are just awful, especially FS Trinitrons. The chance of fixing the geometry to within even 90% accuracy using just the service menu is next to nil. You have to open them up and physically tweak them. It can take a long time and be very tedious. I stopped dicking around with Trinitrons a long time ago for this reason. I will only ever consider an FV Trinitron in the future. Personally, JVC is my favorite brand. JVC geometry puts Sony to shame from what I've seen.

[bobrocks95]

Horizontal bowing can be fixed via the service menu, but vertical bowing doesn't have the circuitry to be fixed. To be clear, that's a bow upwards or downwards along a horizontal edge. Both consumer Trinitrons I've owned have had it along the bottom edge, I think it's a common problem. I pretty much just got over it- my convergence issues are much more noticeable (and hopefully fixable if I ever get those corner convergence strips).

[MKL]

On modern Sony models this adjustment can only be done by moving the deflection yoke (the European late 80's AE1 chassis did have a pot for this though). Not something a noob should try as you can end up with messed up geometry and convergence.

[bobrocks95]

I probably should have been clear that yes, you can attempt to fix it at the yoke, but can't through the service menu. I will be the second to say make sure you know what you're doing first before you mess with the yoke. I'd even practice on a TV you didn't care about if you're serious about doing it.

[Brad251]

I just want to be clear. Am I correct in that the problem I am describing is "horizontal bowing", as it is a bow along a horizontal edge from left to right? Wouldn't any bow from left to right on a crt be a "horizontal bow" and any bow up/down or down/up be a "vertical bow"?

[accaris]

I just want to be clear. Am I correct in that the problem I am describing is "horizontal bowing", as it is a bow along a horizontal edge from left to right? Wouldn't any bow from left to right on a crt be a "horizontal bow" and any bow up/down or down/up be a "vertical bow"?

This should be the correct interpretation.