I just recently acquired a model DTL-H1000 Debugging Station. It's one of those really old Japanese units with the separate S-Video connector still built in. However, there are a couple of oddities about this unit and I need someone else with another old DTL-H1000 to confirm my unit isn't modded or anything like that.
First, booting any retail or burned disc from regions NTSC-U/C or PAL results in the console going straight to the game after the white SCE logo screen -- no black PS logo screen with "Licensed by...". The sound also bugs out until the game resets the SPU due to this.
Second, booting any retail or burned disc from region NTSC-J shows the black PS logo screen, but it also shows SCEI(tm) there in addition to the longer "Licensed by..." text, and it does this even for burned discs. Debuggers usually don't ever show SCEx(tm), right? The PS2 DTL-H10000S is an exception though, maybe DTL-H1000 is another one?
I also opened the unit and didn't see any obvious signs of modding, but I guess I can't be sure unless I disassemble the entire unit so that I get a clear view of both sides of the motherboard.
edit: I also noticed that my Xplorer FX Professional cheat module doesn't work on this console. I wonder whether the parallel I/O port is broken or if this is yet another feature of such an old PlayStation? Perhaps the Xplorer wasn't made with Japanese launch models in mind?