CRT monitor problem: Picture magnifies by itself and loses brightness

I believe this symptom indicates reduction of high voltage. The electron beam becomes fainter but also easier to deflect, so the picture becomes bigger. I'll let others comment on how to fix it.

Sounds like it's Blooming. Problem in the HV regulation, deflection B+ or a few other things. Probably should start looking for a new monitor.

Classic symptoms of nosediving EHT voltage. And thats usually due to insulation breakdown. Once that begins, each successive arc worsens things, so your monitor's not got long left in this world.

A good vac/brush of the EHT bits might clear it if youre lucky, but probably not.

NT

The EHT (Extra High Tension or High Voltage) is decreasing. The beam current goes down, and thus it is easier to have beam deflection, and that is why the picture gets larger.

The common causes can be the HV multiplier assembly, or a voltage regulation problem.

I would be considering a new monitor. The cost of servicing your monitor would not be worth it. The new monitors are far improved.

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Jerry G.

I have a weird problem with my 20" CRT monitor. Every now and then (there are always some hours between the incidents), the picture gets bigger (kinda like zooming in) and at the same time loses brightness. This 'zooming process' lasts for about one second.

After that, the picture is automatically reset and totally normal again.

The monitor does not make any unusual sounds during the occurences. It is a "Gateway 2000", model "VX 1100". I have never had any problems with it before.

I have never heard of anything like that, but I suppose that some electronics part is broken and cant manage to direct the electron beam correctly anymore.

Now, I am not really adept at this subject. Is this dangerous (e.g. implosion)? And also, what could be the reason for that problem?

Thanks in advance! Andreas

I agree with the others. Your monitor will probably go completely dead eventually; I'd get a new one as well if it were me. I've gone through two monitors on my 7-year-old IBM Aptiva 595 and am on my third (Hewlett-Packard Pavilion MX70), but when this one eventually dies I'll just pitch it and get a new FP (flat panel) monitor. The new FPs are better than CRT monitors and take up less room on a desktop. That's all we see anyway in businesses, etc.--FP monitors; no one (that I know of, except myself) uses CRTs anymore. Everywhere you look noiwadays--well, almost--flat-panels are the rule rather than the exception.

I am really impressed with how fast all of you answered. Hadnt expected that. It is nice to know what is happening inside my CRT now. Thank you!

I will definitively replace it with a flat panel, but I'd like to know if I can use the CRT safely until I can get a replacement.

Put in other words: Will my CRT die quietly or will it go with a big 'bang'?

theres not enough energy in the EHT to do anything nasty. It just wont fire up one time, and that'll be it.

NT

just because 'everybody has them' , of course, does not mean we all have to ditch our CRTs. I won't be - the flat panel (LCD I presume you mean by flat panel) ones I saw when out shopping late last year were largely awful - poor black level and colour bleed. Howver they do take up less room which is a plus.

I say to the OP : If you're not depsperate to save 10" of desk space check your local frecycle, you will find people giving away good monitors and it would be nice to 'save' one from the landfill instead of just going out and buying some new thing that will probably last 18 months before dying!

-B.

Before condeming it, you might want to leave it unplugged overnight (to allow the main capacitor to discharge) then open it up and check for cracked solder joints around the power supply and line stages. many faults are caused by stuff this simple. see

for tips on how to go about it. All you need are screwdrivers and a soldering iron.

If you can't find the problem, it's not worth taking in for repair. It should be Ok to use but i wouldn't leave it unattended just to be sure.

Se my other post for suggestions on where to find a new one for free! good luck.

-B

Jeff, WB8NHV ha escrit:

We use flat panels at work and I am not too impressed. Unless used at their native resolution, they look less sharp than a good monitor, and problem is for a 15 or 17" monitor the native resolutions are too big so everything looks too small. Monitors are better at handling all sorts of resolutions.

Late at night, by candle light, b penned this immortal opus:

Once you have it open brush off all the dust that's probably accumulated over time. Use a round soft brush and if possible, follow it with a whiff of compressed air. One possibility is that the dust is shunting off the EHT or other HV.

- YD.

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I have to agree. Seeing is not one of the things I do particularly well, so I run my 19" CRT at 800x600. You can't really do that on a flat panel, and changing the DPI setting in XP gives you some strange artifacts. I'm told that's much improved in Vista though, so maybe there's hope for me yet.

Or in Windows XP if you turn on ClearType.

I've found the opposite to be true for me, it's been hard to find a flat panel with sufficiently high resolution. I'd love to have a 20" with a

1920x1440 resolution, I tend to keep a lot of things open at once and like to have lots of space on my desktop.

This ain't what you asked, but I'd be concerned... The death of the monitor is NOT your primary concern. CRT monitors are run at about the maximum voltage you can get away with without generating excessive X-rays. If your voltage is normal but dropping as you increase brightness, no problem. But what if it's unregulated and going HIGHER when you turn down the brightness??? That's what happens when the bleeder resistor goes open. Can't tell from your description. But how much risk do you want to take with your eyesight?

Where'd I put my flameproof suit??? OK, let me have it...

mike

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Thanks to all of you! I really appreciate your help.

I might open it up just because I want to know what it looks like on the inside, but a flat panel will give me so much more space on my desk, so I am actually looking forward to the day the CRT doesnt work anymore!

Andreas