PC Monitor Losing Its Sharpness? Weird...

[dj_mocok]

This trimport, do I need to open the monitor to adjust it? And how can I know which one to adjust and how much should I need to adjust?

I don't think I will be servicing this monitor, it's not worth it cost-wise.

 

[helix]

unless the phosphorus is lossing it's lumiosity or the tube is leaky most tv repair shops should be able to calibrate and degause it making it useable.

 

[Fitz]

You'd have to take the plastic shell off, and possibly a metal cage off (some just sit loose on top, others are screwed down). They should stand out fairly well, being on a raised part and facing straight out to the side (rather than flat on the main PCBs), and also have a much larger knob on the trimpot, such that you may be able to turn it by hand. I've seen some monitors that have an opening in the metal cage directly to these trimpots, but don't count on it.

The only CRT monitor I have right here is an extremely old one that may not have things in the same spots, but I'll pop it open and if it has them in the right place I'll snap some photos.

Edit: And don't touch anything you aren't 100% sure of.

 

[Fitz]

Okay I found a monitor I didn't think I still had in my closet, which is a good example of what I was talking about. Remember though, your monitor may have these in a slightly different location, or not at all, but it is more common to have them than not, in my experience.

Outer shell off:



Inner shell off:



This is the area where the focus adjustment resides:



Closeup of the trimpots, you can't tell but it has 'FOCUS' embossed on the plastic between them:

 

[milhouse6]

One of my 21"s lost its red gun a few years back. A little percussive maintenance fixed 'er right up for another 6 months. If that doesn't help then I'd cut my losses and buy a replacement, as decent used CRTs are a dime a dozen now.

I've witnessed several CRTs lose focus on their way to the grave. I'll give you 50-to-1 it's not a source issue.

 

[milhouse6]

If you're going to take the case off as per Fitz's excellent photo-how-to, you may want to clear a little more space off on the bed as this may very well be your final resting place.

 

[smeggy]

I lost a red gun on a monitor about 12 years ago and went into mine against all my best judgment, I managed to revive it via trimpots for a while but it's death was merely postponed for a short while. Yes you can go in there and adjust it yourself, but be warned, it is very risky if you touch the wrong thing. Even unplugged a monitor or TV can be quite leathal.

 

[JaGWiRE]

I'm going to personally advise you not to even attempt to open your monitor. Take it to a professional if you want to have it looked at or fixed. Monitors are very dangerous, just like power supplies, even if it's unplugged do not think it cannot harm you.

 

[Gaughtfried]

Quote:

Originally Posted by JaGWiRE I'm going to personally advise you not to even attempt to open your monitor. Take it to a professional if you want to have it looked at or fixed. Monitors are very dangerous, just like power supplies, even if it's unplugged do not think it cannot harm you.

Yup. Those things are giant capaciters just waiting to go.

This blurriness sounds like a convergence problem. I'd first degauss it and then run the Nokia Monitor test and adjust everything to spec. Reading the help file is very useful. Both degaussing and convergence should be something you can access in the monitors built-in menu.

 

[Fitz]

Quote:

Originally Posted by Gaughtfried Yup. Those things are giant capaciters just waiting to go. This blurriness sounds like a convergence problem. I'd first degauss it and then run the Nokia Monitor test and adjust everything to spec. Reading the help file is very useful. Both degaussing and convergence should be something you can access in the monitors built-in menu.

It doesn't sound like a convergence issue to me, since he said the colours still look fine.

 

[Gaughtfried]

Not necessarily.

In the past I've had problems with blurry font and nothing else. In the end I managed to fix them with minor tweaks to the convergence setting.

 

[dj_mocok]

Fitz: Thanks a lot for all the effort and pictures trying to explain, but after seeing that warning high voltage and it doesn't have a guidance how to fix it... now I kinda hesitate doing so.

I can get 2nd hand CRT pretty cheap now, less than 100 bucks, maybe I should do that instead of risking breaking the monitor or injuring myself... hehe...

Maybe I'll sell this one, and then with the money, add it up something else...

 

[JahJahBinks]

save some money and get a LCD.

 

[JaGWiRE]

Quote:

Originally Posted by Gaughtfried Yup. Those things are giant capaciters just waiting to go. This blurriness sounds like a convergence problem. I'd first degauss it and then run the Nokia Monitor test and adjust everything to spec. Reading the help file is very useful. Both degaussing and convergence should be something you can access in the monitors built-in menu.

Yeah, not to go off topic, but I beg the OP not to touch the monitor, monitors have huge capacitors that will still be locked and loaded even when powered off, definitley enoguh to kill you.
A new crt seems smart if you don't want an LCD right away, LCD'S still are evolving amazingly, waiting won't pinch/hurt.

 

[helix]

that picture you put up is of the flyback transformer, it should not be adjusted unless you have a service manual and the test equipment to do it right, 40,000 volts and up is not something to be played with!

edit: one more thing even though the high voltage caps have resistors across them to discharge to save money the makers keep them at a high value so they can use lower wattage resitors, this means even if some time go's by the caps might still be charged, it's not unusual for them to be ~350v or more, on the bigger ones shorting them out with a screwdriver can fuse the screwdriver to the leads (think arc welder) and if you touch it, it can leave burn marks not to metion severe pain.