THE MONITOR SONY SDM M81B HAVE HDCP??

Here is the sony monitor model; sdm-HS95P support page;
http://esupport.sony.com/US/p/model-home.pl?mdl=SDMHS95P


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TRY WITH A OTHER MONITOR ARE THAT OKEY YOUR MONITOR ARE PROBERLY BROOKEN.
ARE THE OTHER MONITOR ALSO BLACK YOUR VIDEOCARD ARE PROBERLY BROOKEN.
ALL CABELS SHOULD ALLWAYS BE SEATED TIGHT.

Either a loose/bad power cable or the backlight is failing.

Check for a loose power cord on the back of the monitor (quite common).

(If this does not explain enough for your issue, please take a few minutes to clarify the specific problem regarding this specific monitor style and Windows 7).

Being that this is an older style monitor, drivers may not be available for a newer operating system, (such as Windows 7). Here is the link to the sony drivers download page:

http://esupport.sony.com/US/perl/swu-list.pl?mdl=SDMHS95P

The newest supported operating system is Windows XP.
The generic monitor driver for windows 7 should pick up this monitor without any need for specific driver installation. Just try plugging it in and it should register automatically.

http://s807.photobucket.com/albums/yy352/budm/Sony%20SDM-HS73/

It can be bad lamps, caps, etc.
http://en.wikipedia.org/wiki/Capacitor_plague

This page from your manual talks about HDCP compatability.Is this your issue?

Sony does not sell replacement parts to the general public, only a Sony authorized repair center can get you these parts.

Yes, lcdpayless.com has this kind special power adapter. You can just search it by model# SDM-M81 at the homepage.
or just click as below link and check it out.

http://lcdpayless.com/productpage.php?productId=4125