PS2 Slim model number query

[Ryu Kazama]

I've got a Japanese PS2 slim that happens to have a model number of....SCPH-*****

What exactly does that mean? There's no usual sticker on the console itself or even the Warranty sticker yet I believe this has never been opened. Does anyone happen to know what this could mean? Usually one refers to model numbers as 'SCPH-XXX' or variants, where the 'X' is a number itself. But this simply *****. So unusual.

Pic attached.

http://i.imgur.com/yvgjj.jpg

[Madigan]

If there's no stickers and it doesn't display the console version then I think that ps2 has a mod chip, but I'm not 100% sure, did you ask the seller about it? all the evidence leads to that.

[Ryu Kazama]

As far as I know it hasn't been opened. It only plays NTSC-J games. PAL games didn't work and I haven't tried a US game.

It would be weird to remove the model number/series number sticker as well - that's a separate sticker to the warranty sticker yet neither are present. Seems so weird.