I don't know that machine, but looking a bit I see what appears to be the
listing you snagged the photo from. In description, it says:

Micron NBP001088 AC Adaptor 18.5VDC 2.45A GoBook

These are pretty common specs for many laptop adapters.

It would be helpful if the system has a sticker on the bottom/back which
gives the power requirements so you can confirm (and would be great if also
the adapter pinout)

If that is the right adapter, and you don't know the pinout, chances are it
should be pretty easy to figure out.

The GoBook photos I see online show it having serial and parallel ports, but
many other PC connectors (VGA, audio, keyboard, USB etc.) will have a known
ground pin ... and having access to ground makes it easy to figure out which
power pin(s) are ground.

The adapter listing only shows one voltage supplied, but at 2.5a it probably
needs more than one pin for the current. I'd wager that you will find that the
connector has two pins in parallel for ground, and two in parallel for +19

Coming up with the right connector might be a bit tougher, but it looks pretty simple,
you could probably make something that would work if you had to.

I was hoping to avoid building an AC adapter from scratch. I have plenty of compatible adapters but I'd hate shorting anything especially on the 19v line. This laptop is pretty rare and they hardly appear anywhere for sale.

MercuryMaurader wrote on 2025-06-17, 23:40:

I was hoping to avoid building an AC adapter from scratch. I have plenty of compatible adapters but I'd hate shorting anything especially on the 19v line. This laptop is pretty rare and they hardly appear anywhere for sale.

Oh I know the feeling, and mostly agree, but initial msg suggested you've not been able to find one in a few months of looking...
and wanted to give you an option (a working classic system with a subd supply is better than a non working one IMHO)

I do think it's worth checking the pins - I suspect you'll find the 4 pins are essentially
connected to two circuits - either as doubled pairs (connected together for more power capability)
or with some pins no-connect.

If that is the case, figuring out which of the two is ground should be easy. The other one would obviously
be the 19v.

In all laptops I've seen the 19v is + .. if you are worried about polarity look inside and you should be able to tell
what it connects to and what polarity it wants (look for polarized caps or transistors)

If the four pins from the supply have more than two internal connections, then all bets are off and I wouldn't
try subing the supply without more research. (which would also suggest that the photo you linked to might be
the wrong supply)