OK,
I have an opportunity to pickup a white PCE pretty cheap. Works but doesn't come with AC adapter.
1 - what are the specs of the AC adapter? Is it the same as the US TG-16 unit?
The PCE needs 9V, will run fine on 500 mA or more, the polarity is positive on the outside. The actual power requirements will be close enough to TG-16, but I'm sure the socket itself is probably different just, you know, because. I don't have a TG-16 to compare. You can buy the wonderful Radio Shack 273-1771 and pick whatever tip you need. That thing will supply a full amp, which will power any NEC hardware you have the correct tip for.
2 - Next - does this unit have the same expansion port as the TG-16? Is the pinout the same?
All the expansion ports are the same except the PC Engine Shuttle.I don't know if it will actually fit in US released Boosters, CD unit, etc though due to case size differences. The pins are the same though.
3 - Is there room to put a US/JP switch in this system, and has anyone done the JP region lockout remove mod on this?
Um...I really don't think so. You could fit one of D-Lites little switching PCBs in it, but good luck getting ahold of one of those these days. Disabling the US lock-out on one of these is easy though, so if you have an adaptor and a soldering iron you are set.
In case you didn't know, these system outputs RF only, and there is a chance that your TV won't tune it at all.