Given the position of the connector in the board and the fact that it has 4 pins, I'd say it likely is the external battery header.

However, before you connect a battery to it you should definitely find a way to find out which pin is ground (easy to do with a multimeter), otherwise you could be shorting the battery if you plug it in reverse orientation. You could try following the traces, but in a multi layer board it can be difficult without some sort of continuity testing.

Ideally you would be able to trace one of the pins in the header through some diodes and resistors to one of the pins in the HD146818AP chip (real time clock), that would be the positive terminal. The pin on the opposite side will probably be the negative, this can be verified by checking continuity to ground.

Interesting board - I noticed the Arche branded chip and remembered that I have an old Arche branded 14" CRT monitor as well.

I would say that pin 1 (rectangular instead of circular pad on the bottom of the board; the one closer to the diode D5) is the positive, as it seems connected to anode of D5. Anyway, on most (if not all) boards the ext.bat. header has a diode in series, so connecting the battery backwards would result in nothing happening 😀

Thanks for the advice. Maybe I'll buy a cheap multimeter as I have many motherboards that need to be diagnosed. As for this one, I might try and connect a battery pack and see what happens 😎

Here is a photo of the case the board was in. The PSU is Arche branded as well, never heard of this brand until now. The Arche chip next to the keyboard connector had a phoenix sticker but it peeled off when I rinsed the board.

quicknick wrote:

I would say that pin 1 (rectangular instead of circular pad on the bottom of the board; the one closer to the diode D5) is the positive, as it seems connected to anode of D5. Anyway, on most (if not all) boards the ext.bat. header has a diode in series, so connecting the battery backwards would result in nothing happening 😀

Quick update - I connected a battery pack the way you suggested and it worked. The system remembered the CMOS configuration and time for a few minutes, I should leave it overnight to confirm but it looks good so far. I'll try to reassemble and clean the system soon and make a thread about it.

Hello, do you know the manufacturer of the ARCHE motherboard? I've got an ARCHE RIVAL 286 motherboard and the only clues are PAT-7.2A and Y-7.2 stamped by the ISA slots. Lots of CHIPS chipsets on the board too. Thanks!

Klench486 wrote on 2023-01-12, 19:51:

Hello, do you know the manufacturer of the ARCHE motherboard? I've got an ARCHE RIVAL 286 motherboard and the only clues are PAT-7.2A and Y-7.2 stamped by the ISA slots. Lots of CHIPS chipsets on the board too. Thanks!

I suggest you create a new thread with pictures of your motherboard and hopefully some of us might be able to help identify it 👍