I am using a 1200A to downconvert 720P footage. The downconvert works fine as I tested it loading it into FCP and the footage is fine DV25 just what it should be. However, when I take the same output (firewire) and plug it into my DSR-1500, the iLink light does not lock up, it just blinks.
I tested the DSR-1500 by loading firewire directly from a DV Camera (VX 2000) and the DSR-1500 locks up to it just fine.
So, best I can tell there is something the DSR-1500 just does not like about the firewire output of the AJ-1200A. However, I tested both machines and the downconverted output of the 1200A loads just fine into FCP (DV NTSC Easy Setup) and the DSR-1500 locks on immediately to the output of the VX2000.
Do you have a component or SDI interface on your 1500? why don't you go out of the 1200A into the 1500 through one of those? Hook the timecode out of the 1200 to the timecode in of the 1500 and set it to external timecode.