Did Sony change Minolta's A mount?

I'm a longtime Minolta MD user, but I quit a brief flirtation with Maxxum gear in 2004 and went with Canon. A few weeks ago I picked up a Maxxum 5000 on a whim - it was $40 and came with a prime 50mm lens. Alas, the camera was a piece of junk, unable to advance film properly, so I "cut my losses" and acquired a Sony A200. Figured I could use that prime and make some good images. I also figured I could buy a M42 adapter and play around with those lenses I have, too.

Funny thing.

On the A200, the M42 adapter didn't allow infinity focus, but it did on the Maxxum 5000. Does anyone know why that could be?

I think it's to do with the depth of the camera body, and the position of the film plane.

Correction -I didn't know that an A 200 was digital, my post should read, the sensor.

That's probably what's going on; the sensor is either closer or farther back than the film is/was in the Minolta SLRs.