What would cause a dim display

[Mr Bill]

This is a lcd monitor that uses ccfl bulbs. Popped up on my local craigslist. Seller described it as needing new bulbs but after chatting with him the symptom is a dim display that is barely visible but is bright enough that you don't need a flashlight. It almost looks like 1 bulb out of the normal 4 is lit.

Sorry for the crappy photo but this is something i have never seen before.

Thanks

[budm]

Re: What would cause a dim display

If any one of the lamp does not work, the inverter circuits will shutdown.
Does the brightness control do anything?

[Mr Bill]

Re: What would cause a dim display

Thats what was thinking to bud. I never did ask about the brightness, i did however do an ebay search and sure enough there is another monitor (same make and model) with the exact same symptom. Could the power supply give off a low enough voltage to turn the bulbs on but not all the way on or would the inverter shut down? I don't know how much "wiggle" room there is before the inverter detects a fault.

[budm]

Re: What would cause a dim display

What is the make and model, it looks familiar.

[Mr Bill]

Re: What would cause a dim display

dell ST2010

Here is the link to the ebay auction. You can atleast have a better picture of the symptom.

http://www.ebay.com/itm/Dell-ST2010-...item35bd3101a1

[budm]

Re: What would cause a dim display

I worked on the 23" version with cracked screen, so I cannot really tell exactly what is wrong with one a shown on the E-BAY.
http://s807.photobucket.com/albums/y...ell%20ST2310F/
For $10 may be a good deal for learning.

[Mr Bill]

Re: What would cause a dim display

I just thought it was odd the ebay one and the craigslist one both have the exact same symptom. I'm debating whether i want to drive 25 minutes but if i doo i'm deffinatly gonna plug in a few spare bulbs i have laying around to see if they fo the same.

[budm]

Re: What would cause a dim display

It will be good to have test lamps for sure.

[retiredcaps]

Re: What would cause a dim display

Could the power supply give off a low enough voltage to turn the bulbs on but not all the way on or would the inverter shut down?

Most lcd monitor pwm inverter ICs are "all or nothing". Either all the bubls work or none at all.

If the power supply voltage is low, the voltage may not be enough to enable the pwm IC VCC pin.

[Rtech]

Re: What would cause a dim display

Have just had a 19" TV, with a very dim screen,and in the end the T-Con board,was not processing the video inputs to it correctly, and a replacement screen restored full operation,,,first time I had seen this sort of fault.