xeon3d wrote:

I'm guessing a normal AT keyboard won't work even though the plug is the same right?

Yes, don't connect anything to the keyboard port until you get this to show something. Also disconnect everything else, like the floppy + hdd

xeon3d wrote:

Would there be something to switch on the motherboard so it doesn't use the CGA internal video and uses a ISA Video card instead?

Assuming that you have the speaker connected and it works, your problem is not that it uses the internal chip and you don't get a picture from the VGA. Let me explain why: without the battery it produces a lot of beeps complaining about the obviously wrong bios settings even without a monitor connected. Your machine doesn't even reach there.

xeon3d wrote:

Would it need a bios battery to show up something on the display?

No, and I'm a 100% certain about this one.

If this thing has built-in CGA there might be address conflict with any ISA-based video card for both BIOS and video RAM decoding. Remove that card and try again. Any beeping or FDD/HDD activity would be a positive sign it actually works.

Can only second and emphasize what @konc said.

Schneider's marketing strategy of using cheap incompatible proprietary OEM stuff to lock the customers into buying only Schneider peripherals fired back.
By the time they released their first actually compatible PC their reputation was ruined so thoroughly that it didn't help them anymore finally having accepted to conform with industry standards.
Back then I usually shrugged my arms and refused to fix Schneider stuff if the problem was not obvious and easily-fixable.
It just would have cost too much time and effort to be economical in any sense fixing that crap.

So Schneider vintage stuff is only for dedicated experts imho.

Yup, Schneider stuff was very difficult sometimes. 😵
On the other hand, though, the proprietary nature gave it a soul, a personality.
The tiny floppy cable that included power pins, for example, was much easier to handle than the IBM standard cable.
Also interesting were the on-board graphics and mouse port. Since I have no matching device of either,
I can't judge, but perhaps they had better performance than the competition of the time (I'm thinking of the mouse thread over here).
Fixing.. It took me a few weeks to fix the PSU for my Tower model. The biggest stumbling stone was myself, though.
I didn't grew up with the knowledge of a 70s engineer/technican, so I didn't recognize the nifty tricks that were known by these guys.
After getting external help and some datasheets/manuals I was able to basically rebuilt the PSU.
So far, it works and the voltages are correct (ISA POST cards are awesome! 😁 ).

I don't really have the time to troubleshoot it, nor to recap anything.
I might give a go at Frankensteining a PSU that has good rails measured and if it doesn't work I'll leave it at that.

Many thanks for your time and input but it seems it's going on eBay soon.

If someone from here wants it, do let me know.

xeon3d wrote:

- I've frankensteined a cheap atx psu and connected the right voltages to the right pins as the board has a non-standard connector, still no boot (and strangely, 12v was still 11.5v rail on that one).

xeon3d wrote:

I might give a go at Frankensteining a PSU that has good rails measured and if it doesn't work I'll leave it at that.

I thought you already did that? That's why I didn't say anything about the PSU

The PSU I frankensteined didn't have > 12v rail.

Got myself an ISA Diagnostic Board and with the original PSU, all the voltage-related leds light up, clk, irdy, frame light up too, but it shows no bios post codes...

I've tried it with and without the ISA VGA Adapter...

Any ideas on where to go next?