On 12/9/2013 5:03 AM, Vedran Vuk wrote:
Hello,

I have a question regarding a CRT monitor which I couldn't quite find the answer to on http://www.repairfaq.org/.

I don't believe it's the usual brightness loss of a CRT over time where phosphors lose their efficiency but wish to confirm my doubt.

The problem manifests in the following way: After a power-on the display seems to have solid brightness levels. However, displaying a full white picture dims the display over a period of some 30 seconds - the picture noticeably loses brightness.

Now if I display a full black picture for a few minutes and then display a full white again, the brightness is back, but starts to fade again like described in the prior paragraph.

Can you please confirm that this is a problem with some driver circuit, or is this in fact an aging CR tube?

Thanks,
Vedran.

How old is the monitor?
Is this a new problem?
Or been that way since you acquired it?

When it goes dim, can you reduce the brightness?
And, by that, I mean does the first step down from max reduce the
brightness more?
What happens if you set it to the level to which it dims and wait?
Does it dim proportionally more?

May be some kind of screen protection function.

I'd also peer at the filament to see if it also dims.