PC Monitors getting dark

[StephenH]

This is not really arcade related, but at our office, we have had several PC monitors, in which the picture is getting dark on (i.e. dim at high brightness settings, and nearly dark at the normal medium brightness settings).

I have not worked on monitors myself (and I am scared of the high voltage), but I was wondering if it is something that is worth fixing, or if it is worth throwing them away.    Additionally, what can cause this condition?

Additionally, some of the old monitors became flickery as well.   Is this worth fixing, or is cheaper to throw them away and buy new ones?

[StephenH]

BTW, many of these are various models of Apple, Gateway, Sony, and Viewsonic PC Monitors.

[Ken Layton]

They probably need some capacitors or possibly the picture tube needs to be rejuvenated.

[ChadTower]

Is that much harder than an arcade monitor cap kit?  I have a couple good 21" 60hz monitors at home that are getting awfully slow to warm up...

[MonitorGuru]

It could be capacitors or it could also be that you are using up the usable life span of the tube itself.  

A cap kit on a random unknown computer monitor probably isn't going to be economically (or time value) feasable.  They don't make "kits" so you'll have to dig around for all the caps individually, and the more advanced the monitor the more caps there are.  I've seen more caps on the video input boards of new PC monitors than on entire boards of arcade monitors. (Not unheard of to see 100+ caps on some PC monitors vs 15-20 on an arcade one).  Also the tolerances are tighter for PC monitors.

I'd bet your tubes are just dying.  The things you can do to brighten them (wont speed up warm up time) are:

- Look for the screen control on the flyback. Turn this up just until you see a white fog appearing on a black screen with retrace lines, then back it off a bit.

- Look for a pot on the circuit board labeled "SUB BR" or "Sub Brightness".  This will let you gain a bit more brightness than the normal brightness control will let you do

- Look for controls or on screen menu options to conttrol RGB guns. (Would be labeled BIAS or DRIVE) Turn them up to full. But warning.. if you mess with these you will affect the white balance of the monitor, turning the bias of white to red, blue or green if you dont move them equally. Colors will be off if you dont get it right.

[Ken Layton]

It all depends on the particular make and model of monitor. Some are easy to repair while others have tons of metal shields to unsolder or layers of circuit boards to disconnect just to get to the one you want/need to work on. There is an excellent computer monitor repair tips site at: www.anatekcorp.com/faq/monitor.htm