Well my Mitsubishi DX-TL900U finally broke. Well, the hard drive gave out, which is normal I guess. The Mitsubishi website said that the unit needed to be sent in to a tech. But the site also said that the operating system was embedded.
So because the OS is embedded the dvr should use the hard drive just as storage. So I removed the broken Maxtor 120 gb drive and replaced it with some 160 gb I found somewhere. My unit, according to the directions does not support multiply drives. But looking at the mother board (picture 3) there is a place for the drive’s power cord and you could probably use a Y connector on the mother board power? It also looks like just a standard ide drive and maybe just a master / slave ide cable will allow 2 drives? I did not try it though because I have never had any space problems. Next you power the unit on and it says “ALL HDD DATA WILL BE ERASED” I did not know what was on the drive so why not erase it all (that mean “initialize”). Then the unit formats the drive and it works. Yea!