CRT monitor - getting darker...

[mh2360]

I have a 17in CRT monitor, which is about 3 years old. As time goes by the picture seems to be getting darker and darker. I now have it set to maximum brightness but the picture is so dark as to be barely useable. Other than that, the picture is rock steady and sharp as a pin...

I know this means it's probably ready for the big recycling center in the sky, but if its just a matter of replacing one or two components, I really would like to save it.

[BJ_M]

it is toast

[Bjs]

Most have a deguass feature , hit it .

Loosing brightness is most likely caused by a failing component , however , it is adjustable on most flyback transformers ( the thing that has a black cable socketed to the tube ) .

Its inside the unit , rear left .

Under no circumstances , when the cover is removed , touch this part with your bare hands , even when no power is connected , it can kill , or most likely , throw you through the wall if you do not know what you are doing .

80,000 volts and counting , not a nice thing to play with .

There will be a number of adjustments on the side of this transformer , one will be for brightness , but there differrent between units .

For the inclinded :

With power removed , remove retaining screws retaining rear cover .
Do not remove rear cover clear of pass though video cable (simpler for minor adjustments) .
Once done , reconnect power ( do not stand near the rear or sides of unit ) .
Cable to monitor first , then to power only .
Come around to the front , and power up .
Now come around left , not close , and look at the flyback transformer carefully .
You should see what appears to be some adjustment points on the side of the flyback transformer .

One of these is for brightness adjustment , the others are for other adjustments .
It would be handy to have the schematics for the unit .

Brightness is not the real term , its simply failing to deliver enough power to the tube which causes this effect .

Note the position of the first adjustable item , using the screwdriver , adjust it by one 1/4 turn .
Note the change on the screen , should this make a change other than to brightness , return it to its default position .

One is for brightness , one is for contrast , and another for horizontal control , but as I can not find my service manual , I just have to report it off the top of my head .

There will be others around on the board related to color adjustment , but leave them alone , as you may have to be close , and in some cases , they put the adjustments in ridiculous places , which is sure to burn the unwary or worse , samsung is an offender when it comes to this , got to remove the tube in some units .

Once brightness adjustment control is recognised , it will be easy to make the adjustment required .
Turn unit off , power off at power socket first , then reinstall the rear cover .

The only issue remaining , is just how long this will hold , the flyback transformer is on its way out , and just as easy to go buy a new lcd , because to replace the transformer would equal above half the price of any decent lcd screen these days .

It's highly possible it will hold for a month or even longer , but it will come back , sometime .

Of course , this could also be an indication something more related to the video adapter in the pc , might be the cause of the problem , something worth checking before playing about with the monitor , as a rule .

[yoda313]

You know I have a 17inch crt monitor that is showing some odd symptoms too. Its an emachine monitor that is three or four years old - the same age as the computer it came with.

I had replaced a ati video card that went screwy with an nvidia card last year and Haven't had problems until just recently.

The screen will go pinkish on me for a little while (few seconds) then flash back to normal - not dramatic flashes but it will correct itself. It appears to be the entire screen and not a portion of it. I haven't tested it with a movie or video game yet over prolonged use. Its just been the last week or so I believe.

Is this an early sign of tube failure? I'd hate to think it could only last few years. How much are 17inch tubes going for now? What about 15" nonwide lcds???

[Bjs]

Well order this :

A:

On the off chance , theres a type of alcohol used for cleaning pc components available .

Turn the system off at power point .
Disconnect the vga cable from the video card .
Clean the pins on the cable .

Next .

Remove vga card .
Clean the contacts of the vga card gently .
Clean the contacts running in the vga connector on the motherboard .
You will need something small , so as to also clean the pin contacts that the vga cable connects into as well .

When you clean , use this product sparingly .

Leave for 20 minutes , then when you come back , make sure all cleaned components are dry with no trace of the alcohol fluid used for the cleaning process .

Reinsert vga card , if fan included , check its dust free .
Reconnect vga cable .
Restart system .

Confirm if fault diminishes in nature .

B:

Rule out part a first .

This one is normally associated with the horizontal hold , and is tunable , as there is an adjustment on the flyback transformer for it , but is more susceptible to faults lying within the circuits involving power input starving the flyback transformer , a similar situation for brightness and contrast control .

The unsteady nature indicates an issue with the power input circuit has developed in this case .

It is possible it will continue for sometime , but there are many different situations and work loads between systems which play there part . you'll know when the limit has been reached as it will turn on one day , and all you'll get is a bright line in the center going across the screen in the horizontal position .

Not quite game over , but it will cost to have it repaired .

----

The last time I had to have a 17" crt repaired with this issue cost around $110.00 au to fix and was just on 3 years old , which is why I have a sought , and bought a collection of service manuals .

But that monitor is still going strong 4 years later , it can not die until I say it can , or I find something better to replace it with .

So consider it this way .

Do you justify the repair , with the possibilty of the added costs of transport to and from the service centre , or would it be better in the long run to buy a new lcd .

Crt's are available , but not a highly stocked "off the shelf" item these days in stores , and the repair to the old unit is not guaranteed to survive past the warrantee the service centre might provide for their work on it .

Most dont these days .

----

Electronic connections suffer from oxidization over time , many systems over 3 years old tend to be problematic when it comes to addon parts being inserted into motherboards , either as replacements , or a litle extra help , like another stick of memmory .

It can also be a condition created by a failing gpu , theres only one way to tell this , and thats with a monitor in a known good working order . Yes , I coped that one myself 2 years ago .

If you want electronics to survive a long time , it is best to shut the thing down , and turn it off at the power point when its not needed to perform a function .

----

Last , try moving where the power source comes from , I mean , try another power point in the place and see how it gose , some devices can cause intermittent power fluctuations if on same line , which you migh be unaware of .

Places to note :

1: Do not burn to media , if washing machine is on same line and active , she got me twice .
2: Same gose for toasters on same line , again , she got me .
3: If she's out with the power vac , forget it .
4: Near by electric heaters is a no no .

The microwave made no difference , what the ?

[mh2360]

Of course , this could also be an indication something more related to the video adapter in the pc , might be the cause of the problem , something worth checking before playing about with the monitor , as a rule .

Its not the graphics card, i've tried a few with the same results.

I'll probably buy a new LCD, whats the average lifespan for these?

[edDV]

CRT phosphors dim with age. To compensate the high voltage circuit output can be increased when the contrast control is cranked up. This works for a while until the limits of the HV supply is maxed. Then the picture continues to darken until the HV supply fails from running at maximum.

To fix you would need a new CRT and a new high voltage supply plus a complete readjustment. This would likely cost several times replacement cost.

LCD failure will likely involve a flickering or failed back light. Some a re easy to repair, others are not.

[Bjs]

Its look into the magic crystal ball on that one , only researching users comments might show some evidence on whats best , and then theres the price , in au , we get over charged for them .

Whatever there warrantee "implies" .

My viewsonic va903b is not 6 monhs old yet , but I have seen others well past 3 years old , and could do with a proper clean .

I have users here that dont want anything bigger than 15" and in crt only , but their a dying breed , screen wise I mean .

Which means more fangled service manuals to get hold of later .

[Bjs]

CRT phosphors dim with age

Most dont know its possible to "flash" this problem into the past , I have a tool for that , but its only good for around two years , maybe three years tops , then it comes back gradually once more .

Flash the sucker again .

Costs about $40au to perform that task .

Lcd failed back light , been there , fixed that for another user on an lg unit , thankfully no parts required .

[edDV]

BTW, I'm still using a 1997 19" Hitachi CM751 CRT for word processing. It has gone a bit dim (contrast maxed) but convergence is still spot on.

That monitor was bought with a PII 300MHz computer and has survived PIII 800MHz, and P4 2.4GHz replacements.

I also have two 1991 NEC 5FG 17" in my basement lab that still make bright pictures.

[TimA-C]

Just a thought, but can you offset the dimming by tweaking the settings in your graphics driver? My nVidia cards have allowed me to prolong the useful life of at least two ageing CRTs.