NEC PC-9821Na7 / HC7 power supply

[kuro68k]

I'm looking for a way to power my NEC PC-9821Na7 / HC7. The official power adapter is an N-U01 I believe. It's got the 4 pin rectangular connector.



Any idea where I can get one, short of importing from Japan? I keep an eye on Japanese sites but I was wondering if there were any models available in Europe with the same connector, or if the connector itself was some type you could buy.

And does anyone have the pin-out for it? I could probably get 12V into it if I knew which pins were which, although there being 4 of them makes me wonder if it's got some kind of communications.

 

[sqpat]

Photos of the adapter here including pinouts and amperage/voltage info.

https://jp.mercari.com/item/m34901211744

 

[kuro68k]

Thanks sqpat. From your link I was able to then find this page with more info: https://98epjunk.shakunage.net/pow/98_note_ac.html

That site links to some tweets which show it seems you can bodge it:

https://twitter.com/x/status/1496778622484369410

It seems like one of the power pins is for battery charging and the other is for running the laptop, but it's not clear why they need two separate ones. Maybe the battery charger circuit is noisy.

I will try bodging it, although some of the comments make me think that maybe it will need recapping before it works. I'll use a bench PSU with current limiting and see what happens.