Sony PVM-2530 problem

Hi all,
I have a Sony PVM-2530 and a few weeks ago I started experiencing a problem. I'm hoping someone offer a suggestion as to what the cause (or solution) might be.

Here's what happens:
The picture tube will turn itself off after about 15 minutes of use. The unit is still powered and will still output sound. I can hit the power button (turn it off) and when I turn it back on, all is right... for another 15-30 minutes. The length of time varies.


Any suggestions?
Thanks in advance.

Is it set to sleep at 30 minutes?

I hadn't thought of that, but I just looked through the manual (a pdf version found online) and there is no mention of a sleep feature. I don't have the remote for the TV but the remote pictured in the manual doesn't have any type of menu option.

Does anyone know of a hardware failure that could cause this?

That's a monitor, I don't think there is a remote is there?

There is a remote made for this model, but I don't have it. It's pictured and described in the manual.