Focus adjustment on monitor

[Deskstar]

I have an IIyama Vision Master Pro 450 whose focus on the edges of the display are just a bit blurry. What monitor "adjustment" controls focus?
I have played with all the usual options and gotten the shape of the display absolutely square (no distortion) and the color just where I want it. I have played some with "landing" (which seems to only control color).
I have played with H-convergence and V-convergence some, but cannot seem to get it so that both the center stays sharply in focus and the edge is in focus; are these the main "focus" controls or should I try something else?

 

[Gosharkss]

There are ways to adjust focus from the inside of the unit, however I do not recommend you open the monitor. Monitors have extreme high voltages. If the unit is still under warranty, call Iiyama and see what they can do for you. If not a local TV repair shop may be able to help you.


Good Luck
Jim Witkowski
Chief Hardware Engineer
Cornerstone / Monitorsdirect.com

 

[Deskstar]

Thank you, Gosharks; I certainly will not open my monitor (electricity and I do not coexist well) and will do as you suggest.

 

[dkozloski]

With practcally any CRT device the focus can be improved just by turning down the brightness. You also get the added benefit of having the whole works last longer. Sometimes the only way to have a reasonably focused image across the entire screen is to sacrifice brightness a relatively small amount.

 

[jamarno]

Turning down extreme brightness does usually improve the focus, although circuitry is supposed to automatically do this. Turning down the contrast also helps because the video amplifiers have better frequency response when they don't have to amplify as much.

The focus adjustments are usually on the back of the flyback transformer, which is a block of plastic roughly 2-3" square with a thick cable coming out of it going to the side of the picture tube (up to 30,000 volts). It also has an adjustment labelled SCREEN, which you don't want to touch because it affects the tint. There are probably 2 focus controls, one for the corners and edges, the other is for the center. Some monitors have tiny holes in the back through which you can reach these controls, and you can adjust them by using an 100% plastic screwdriver, one with a plastic shaft (a plastic handle isn't safe enough, nor can you just wrap electrical tape around a metal shaft). Radio Shack, Fry's, and electronics supplies sell them.

If you're very careful, you can adjust the focus even if you have to remove the back of the monitor, but you'll need a non-metal table (insulating a metal table is not enough), a wall outlet that's protected by a ground fault circuit interrupter (GFCI or GFI - test it just before use because some don't shut off the current as they should), a mirror to look at the monitor while you're in back, and rubber-soled shoes. Don't touch any metal parts, even when the monitor is turned off, and keep your other hand in your pocket so that if electricity goes into one hand, it won't travel through your heart and out the other hand. Also don't do this alone - have someone who can call 911 and administer CPR if you get shocked. Real technicians will protest that a GFI isn't enough protection and that you should use an isolation transformer, but if you have one of those, you probably already know how to work on the monitor.

 

[sitka]

thanks jamarno, good info, I'm off to the bathroom, its got an insulated table, mirrors and a GFCI. LOL

Can these adjustments correct banding along edges, like slight yellowing, etc.?

 

[jamarno]

The focus adjustments won't do anything about the color, and while turning the screen knob can change the overall tint, I wouldn't do this because the user adjustments for the colors are better for that. Localized tint defects are due to misaligned purity (beam landing), which can be caused by the magnetic field of something like a speaker or electrical device, but if there are objects nearby, try degaussing the monitor and then maybe manipulating any user beam landing adjustments (unfortunately, few monitors have them). Adjusting the beam landing internally requires rotating the purity ring magnets (will likely upset the convergence) or adding or relocating small magnets around the picture tube. These operations are very dangerous because they have to be done with the monitor turned on, and exposed, potentially lethal, high voltages are present.