When it comes to Schneider PCs, as far as I have heard / read it´s a _lot_ of work to find all the interrupted traces, some inside the PCB.
There are some very helpful threads about that also pointing out the connections you don´t see, but I can´t remember where a.t.m.

Is the EuroPC mobo multiplayer, though? At least the service manual implies that it would be just a two layer board. Nevertheless, I’m going to hook it to my scope to see if there is any signs of life in the system.

Couple of observations, though. The floppy drive isn’t spinning at all. Not sure if should spin right at boot. I tried disconnecting the floppy but that didn’t make a difference. Also tried replacing the Nec V20 with the original Siemens 8088 to no avail.

I did some measuring. The CPU resets, it has clock and there is activity on the address and data lines. It’s beginning to look like I have to do some broken trace hunting.

RetroBard wrote on 2023-01-24, 19:43:

I did some measuring. The CPU resets, it has clock and there is activity on the address and data lines. It’s beginning to look like I have to do some broken trace hunting.

Most often, the bad traces are on the bus lines connecting the JIM chip (a Schneider custom chip) to the data bus. The address lines are very close to the battery, and likely to be damaged. It might be helpful to do a continuity test between the pins on the ISA connector and the corresponding pins on the JIM. At least for the address lines, there is no buffer inbetween.

The EuroPC lives again! The AEN line between JIM and PVC4 had corroded away. After yet another bodge, it POSTS and boots. I need to find more suitable bodge wire, though. It has got to be the mother of all ugly bodges with the wire I had at hand.