Screen display

A friend asked me:
"Have you ever had your screen expand to a point where you could not see the file close box or any margin top,bottom, left, right etc. then here a soft "boink" and the screen pops back to normal after a few seconds? This has happened. on and off for the last month or so. "
I thought this happened right before my monitor died. Any other things this could be? thanks

 

Besides a failing monitor the graphics card could be going bad or needs re-seating. You could also have a corrupted or wrong version driver. Another thing to look at depending on the graphics card is whether the power supply is putting enough out to power it.

 

Will check out those things. Thanks for your help.

 

"Boink "? Noises are not a good sign.

Something else I would consider. A normal monitor screen ratio is 4:3, so native resolutions are in that ratio, that is, 800 X 600 or 1024 X 768. If the person is using a different ratio, the monitor (or graphics controller?) might be having trouble setting that resolution. For example, a ratio in 16:9 is a wide screen ratio. If you set a wide screen ratio on a standard monitor you would probably need to adjust the monitor controls to fit the image on the screen, effectively making the view out of range then forcing it back in again. Check that they are using resolutions that suit the screen.

If high resolutions are being used, along with high colour and refresh rates, the system will be working very hard to produce the image on the screen. For high settings you need good quality equipment. Is it getting "flogged to death "?

Matt

 

several causes for this, one of which is low EHT on the monitor

if the EHT is lower than it should be, the electrons get accelerated less; moving slower, they have a longer time to get deflected up/down/left/right, so you end up with a larger picture (generally only a little dimmer than normal - you tend to notice the size change before bad focus or convergence problems manifest)

If something suddenly disturbs the EHT voltage, you generally hear some sort of noise (even if you aren't directly hearing the noise from a spark or the like) - the change in EHT makes things "twitch" audibly.

[SIZE= "1"](aside - but interesting ! - "electrophonic" sounds, such as can occasionally be produced by meteors/meteorites; the only sounds which can "travel" at the speed of light. Really!)[/SIZE]

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Unfortunately from your description I fear that you may be just too late in this case. An overloaded EHT (causing the larger picture) which then failed... I hope not, but it doesn't sound good.

It may be worth trying to clean things up, though. Dirt gets attracted to high voltages - and how!

Recently, I took on a second-hand Dell 17" multi-sync CRT monitor; powering on for the first time it could only make 640x480; 800x600 resulted in a very unhappy display + fizzling noises and attempting 1024x768 caused the monitor to shut down altogether. These resolutions / refresh rates should have been well within it's capability...

...it was a couple of years old, and had been hanging around in a colleague's garage (cold & slightly damp) for a few months. Dust + damp is even more inimical the high voltages than dust alone!

Inside, the dirt clusters around the high voltage points (around the blue preset RT2); looking closer shows quite clearly how the dust and dirt, attracted by the high voltages, forms itself into conductive paths - 1 & 2 are bridging across the track (A, B) of the preset RT2; 3 & 4 are paths from B to the head of a chassis s*c*r*e*w.

Cleaning this monitor made it work again.

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If I'm along the right lines, your EHT section may well have failed; BUT ! it may just be protecting itself (much in the way that better monitors will self-protect if you use them at resolutions which they cannot handle).

The EHT supply is regulated anyway (the EHT voltage is regulated - it has to be, in order 1) for the monitor to work properly, & 2) because of health/safety reasons about X-Ray emmission). The regulation circuitry may well incorparate "out-of-limits" protection - it this is the case, then it may just have shut down.

If you are brave enough and careful enough to look inside, vacuuming out the muck might work. Vacuuming is far preferable to using a blower can in this case, you really need to s*u*c*k the dirt off the board rather than blowing further in.

sanity warning ! - monitors have really dangerous voltages inside, which can persist for a while after you turn them off. Particuarly, if you remove the EHT connector from the tube, the tube itself can easily hold enough charge to kill. Seriously. The inside of a CRT monitor is far more hazardous than the inside of a PC.

It may be worth cleaning the outside of the glass for an inch or two around where the connector cap is - that's a classic place to get tracking (carbonised dust forming into a conducting line along the surface of the glass). You don't need to take the connector off to do this, just work around it. If you can get hold of IPA (isopropyl alcohol) use that; otherwise, just use a dry tissue.


best wishes, HJ.