Old CRT monitor hisses at 720p+

April 29, 2012 at 10:06:23
Specs: Windows 98 SE
Recently I got a old CRT monitor that at first it worked just fine with the exception that on power up it used to make a huge spark on power up in the lower right corner of the screen. It still does a small spark around the screen and its only visible in the dark.
One day later it started hissing but if I lowered the resolution down to 800x600 it would stop for some reason. After that I let it rest for a week or two a then it stopped hissing again for another whole day. I would like to know if there is a way to repair it.

Another problem it has is that the image is tilted a bit counterclockwise and, strangely, more at the bottom than above.

I don't know what model it is since it probably written in the back, all it says in the front is "//// LASER" and it has analog controls.

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April 29, 2012 at 10:20:23
DO NOT open it or play with it. Lethal voltages can exist even with the power off, Danger of implosion exists, toxic material and flying glass will be everywhere.

From an energy use point of view, you ought to recycle it.

These old crt's have both a high voltage issue and the normal electronic issues. I can't say why a resolution would cause a hiss but on some tv and crt's that were loosing their high voltage this may happen.

Text, talk, drive...CRASH.

Hang up and drive @#$%^^

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April 29, 2012 at 14:17:32
I used to repair TV's and have ideas about both issues you describe. However, I agree with jefro it would be most unwise to start poking around inside it unless you are familiar with such things.

Your best bet would be to pick up a cheap or used LCD monitor. Most likely the picture would be better too because CRT's definitely age.

Always pop back and let us know the outcome - thanks

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April 29, 2012 at 15:28:31
CRT monitors use more than twice the power of a new LCD monitor. I don't know about you but for what I pay in electricity, this would pay off the LCD monitor in less then a year.

At what I pay, I just did the math, If I ran a CRT monitor 24/7 it would cost me $233.67 a year.

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April 29, 2012 at 17:24:49
"Your best bet would be to pick up a cheap or used LCD monitor."

I already have one.

"Most likely the picture would be better too..."

No because the blurry picture I get at lower than max resolution and the higher contrast=crappier colors+whitening is obviously worse than the always clean image plus bright and colorful with no whitening even at full contrast.

In other words LCD monitors have a very crappy image and CRT have a quite good and clean one. However I don't seem to find any CRT with a detachable VGA cable except for this one and since these cables break so easily this is really a problem.

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April 29, 2012 at 20:02:03
LCD Monitors have a native resolution. Running then a anything but their native resolution will nearly always result in loss of quality. They are not meant to be run at anything but their native resolution. This is because LCD monitors have fixed pixel size whereas CRT monitors have a variable pixel size,

A monitors LCD monitor run at its native resolution is as good as if not better than any CRT monitors as far as resolution goes. The only advantage you might get with a CRT monitors is in colour reproduction and even that is debatable unless you are a graphics artist producing pictures for print.

CRT monitors are absolute, they use technology that is over 70 years old. . There are only a few companies making them any more and most of them are going to the professional market with a price to match.

But I agree with others, once a CRT monitor starts misbehaving there is little that can be done economically unless you are an electrical technician with all the necessary test instruments and the knowledge not to kill yourself..


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April 29, 2012 at 21:44:56
I agree with everything StuartS said.

I have several CRT monitors and I'm going to use them until they die.

I had a Mitsubiihsi Diamond Scan 15' VGA monitor that I used nearlly every day, more hours per day as time went on, until it died about two years ago. I bought it new in 1997 ?

I learned way back when I took an electronics course in high school that when CRT TVs first came out, they were deliberately designed so that the high voltage circuits could not produce enouigh current to kill a person ( at least not unless they're doing something like standing in their bare feet or in water at the time). It isn't the high voltage itself that kills, it''s the current.

It's likely that still applied / applies for the later TVs and computer monitors. It still applied when I took the course.

However, the jolt you get is just like getting a jolt from a spark plug wire on a car when the car is running - you're likely to involuntarily jerk your limbs or your body away and you could injure yourself when you do that.
(Vehicle ignition systems were / are also deliberately designed so that the high voltage circuits could / can not produce enouigh current to kill a person.)

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April 30, 2012 at 05:47:27
Yes, the CRT EHT is generated via a small transformer from the line scan. Both the voltage and the current fall rapidly, when a load is applied which is much more than that of the small beam current.

The real dangers were way back in early TV history (pre-WWII) when EHT was derived from a whacking great mains transformer in the bottom of the box. Although these 9 inch CRT's only required about 2 kV the prospects of electrocution were high because the the current available was quite enough to kill.

As always, it all shakes out to Ohms law. The current is the actual killer but voltage, current capacity (effectively the internal resistance of the source) and skin resistance all come into the equation to produce that current.

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April 30, 2012 at 07:04:22
Where I am in Canada there were no TV broadcasts until 1954, and by then all TVs made for use in North America (all of them were made in the US or Canada back then) were deliberately desgned that way, if not before that.

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April 30, 2012 at 09:18:23
TV broadcasting happened before that in the UK (1930's) but it was limited hours and only the wealthy could afford sets. Serious TV broadcasting started in the early 50's, the Queen's coronation in 1953 bosting demand here. By then the old transformer design had been put to bed, although some old 9 inch sets would still have been in use. I've seen them in wartime and very early 50's UK movies.

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April 30, 2012 at 12:35:47
Any of the CRT's made before about 1965 might have 20KV or way more on the HV side. That created X-rays to be emitted. It was so bad that children close to the sets could have received too much radiation.
These old sets are equally dangerous because glass is not a solid at room temperature. In the 50 years or more they have sat, the glass has slowly flowed. It gets more weak on the top and the risk of implosion increases.

CRT's are just a crummy product. The factories that made them are environmental nightmares. Working on them is next to impossible since parts are not easy to get.

As above a LCD or LED or even a plasma would use less energy, Many of then newer ones are pretty good from and environmental point of view.

As with all this stuff, I keep it on a power strip. It all gets turned off when not in use.

Text, talk, drive...CRASH.

Hang up and drive @#$%^^

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April 30, 2012 at 12:43:49
Yeah, and at 20 kV (a bit more in TV's) when you got EHT arcing you smelt ozone.
I don't think that was too healthy either.

Of-course they have only become a crummy product because much better things have become available. They were definitely a better bet than John Loggie Baird's wheel:

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April 30, 2012 at 18:13:40
If the crt is a must....check the garage sales.....usually $5.00

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