Original Post

Here’s something I’ve been noticing for a long time: with screen glitches, not every game reacts the same.

For example, Mario’s Tennis is almost impossible to play on my VB because of the garbage appearing on the screen.

Red Alarm, on the other hand, is usually OK, until you get hit by an enemy missile, and the screen goes red for a few frames and then glitches start to appear mainly when you pause the game and the menu appears. When you go to the Options menu and lower the brightness it works fine. Well, at least that’s what it’s like on my VB. Looks like only games which use sprites a lot (Red Alarm only uses them in the menus) are really affected by screen glitches…

…but why?

6 Replies

Hmm not sure… maybe its to do with how many objects are on screen at one time? sorta like framerate, if it cant keep up with the game and it has a glitchy display… its going to fritz out. When my virtual boy had glitchy display in the right eye it only did it in teleroboxer, maybe because its a big game with alot of action, not sure lol. games like mario tennis and v tetris didnt go glitchy however.

hope it helps

It depends on which pins lost contact, and probably what other pins around it are doing, and other random processes (since it’s a floating input when it’s disconnected).

Like: http://www.projectvb.com/tech/displayfix/dispwithlines.jpg , one of the row pins is floating, but continually being read high, so you always get lines. This one: http://www.projectvb.com/tech/displayfix/glitchydisp.jpg looks like one of the row pins is floating and follows the other bit, since there’s bright lines when there’s dim pixels, but black when there’s none.

And you get similar problems with the brightness. Some are more noticable than others because of the brightness settings though.

If you’re curious what specifically is wrong, I posted a display tester app a while ago that you could try (if you have a flash cart).


If you’re curious what specifically is wrong, I posted a display tester app a while ago that you could try (if you have a flash cart).

I’d love to try that but I don’t have one.

To expand a bit on what DogP said:

The VB (like most digital displays) produces grey shades using pulse-width modulation (PWM) which means it turns the LEDs in the arrays on and off, at full brightness, for differing lengths of time. This oscillation can induce spurious currents in nearby wires and, as DogP said, the disconnected rows of pixels will behave differently based on what their neighbors are doing. This is also exacerbated by the fact that the VB uses a synchronous, serial transmission system to shift pixels into the LED arrays.

I’ve also noticed another thing: sometimes, when I move my head away from the screen, screen glitches appear, and then when I look back into the screen they slowly disappear. Does anyone have an idea why does this happen?

I’m not sure… I’ve never seen that, but I’ve heard others say similar things, like playing in a dark room fixes it, etc. It seems highly unlikely, but possibly the displays are light sensitive, and a display with a weak cable connection will be driven by the bad connection, but when there’s light coming in the front, it generates a charge that overrides the weak input (going back to the floating input thing again).

That’s a total guess though… without seeing it first hand and doing other observations, I can’t really say anything for sure.



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