Wiring the control box up again - Mesa boards and P330 Tiny PC. Magic smoke!!

Before I start, here's what we have today. There's an ASrock J1900 Mini-ITX mobo in that black box, along with a Mesa 5i25 Superport board. The breakout boards 7i76 and 7i85 are mounted on the lid. I will leave the PC in the box where it is, in case I want to flash it up later to access any files. Besides, there's no benefit in removing it and I'm not about to remount all the wiring and boards.

The 7i76 has some messy wiring on it that needs to be tidied up later. These are the limit and home switches for the X and Z axes and I clearly never got around to terminating them in a workmanlike manner.

TB6 is the "field inputs" section, where these limit switch inputs terminate.

With the lid off, we can see the 5i25, which is mounted on the case and connected by a couple of ribbon cables to a PCI-to-PCIe adaptor - the 5i25 needs an old fashioned PCI slot but the mobo only has a PCIe slot. I need to recover the 5i25, then reassemble it, leaving it operational, just in case.

Removed.

Here's the old adaptor, alongside the new one, which uses a USB-type cable to communicate with the PCIe plug. That's handy, as there's no room inside the Tiny PC for the 5i25. Both use the Asmedia ASM1083 bridge IC.

Back together again.

A quick note of the 256GB SSD and 8GB RAM:

Only one slot is occupied, so could increase memory if I have some spare.

New adaptor board in place, cover ready to go back on. Looks good to me. It could almost have been planned:

The 5i25 plugs into to the adaptor board. But when I do this, the PC won't boot and the 12V supply shuts down. Clearly something not right here. Note the brown smudge on the PCI edge connector - that PTC has let some smoke out!

The root cause of the problem is actually visible in ths pic:

This is how I assembled it, with all external connections at the same end:

But in fact, this is how it's supposed to be fitted:

From Wikipedia, it seems that this PCI board is "Universal (3.3V & 5V) 32-bit PCI Card", which can be fitted the wrong way round. If you have the mounting bracket and are fitting the board into a mobo, perhaps there's less of a risk of getting it wrong.

So because of this, the 5i25 has 2 slots, allowing it to be fitted either way round. Have I popped something? That burnt PTC ("self resetting fuse") is protecting the 5V supply to one of the BOBs. Luckily I'm not relying on that route, as they have their own dedicated 5V PSU.

No. Luckily, the PC, adaptor board, 5i25 and breakout boards have all survived. TFFT!

And yes, the PC still works and the BOBs appear to be functional. Onwards and upwards!