have the same problem... just one long ..long..long.. beep... one with knowledge needs to start looking with a osciloscop the 74 chips, adress lines, data lines, etc..

Before you start testing everything with the scope make sure that:
1) There isn't any corrosion from battery. Even if battery was already changed perhaps some traces were already corroded and not cleaned properly.
2) Is the PSU working properly? Are all voltages present and in spec?

Re 1: Some corrosion can be under chips, impossible to see without desoldering. If you have any suspicions about that try finding where the trace leads to, and measure point to point resistance. That's a lot of work but it's safer than desoldering these old PCBs.

Re 2: Sometimes the tantalum caps short but if that is not the main power rail the PSU won't trip. And the cap will not catch on fire. So test the secondary/low power rails on the mobo (-12V, -5V) to see if all voltages are present.

If everything looks good then you can start poking around with a scope. Since you do get a beep then it means something is running. Most likely CPU is OK and so is BIOS ROM. It could be DRAM failure for example.

EDIT: Forgot the obvious: Re-seat any big socketed chips. Like BIOS ROM. CPU as well if socketed. Then RAM chips. Some of these older sockets are not great and develop oxidation issues over time.

Disconnect (or don't) power supply connections and check voltages. You can touch and hold the negative lead to the case as everything is referenced to ground.

Unsocket all socketed chips (but label.or photograph their locations and orientation first!!!). Spray board down with contact cleaner. Allow to dry thoroughly and completely!!! Leave it in the sun or in front of a fan. Replace chips, see what happens.

Thanx guys, will try. I tryed isa-tester - it seems all ok with voltage... will try to reset MS and will check battery. Any way - it is fist step is to clear cmos

I think the EuroXT needs a working Dallas chip. (but I am not 100% sure about that)

dr.zeissler wrote on 2025-03-10, 18:36:

I think the EuroXT needs a working Dallas chip. (but I am not 100% sure about that)

It has a standalone battery like the EuroPC and PC2, just at a much better place causing less problems when it leaks (it's at a corner of the board, not in the middle)

Where was this contraption made? Please don't say Europa 😀.

oldhighgerman wrote on 2025-03-11, 10:35:

Where was this contraption made? Please don't say Europa 😀.

Germany, they started in West Germany to be precise.
But "contraption"? No, they are well loved.

oldhighgerman wrote on 2025-03-11, 10:35:

Where was this contraption made? Please don't say Europa 😀.

Schneider Rundfunkwerke AG, W-Germany.

It was one of the few PC models fully designed and built there.
Including motherboard PCB, PSU, chassis and CPU (Siemens 8088/80286).
BIOS was licensed by Phoenix.

Other manufacturers were Siemens (Siemens PC-D, PC-X) and Siemens-Nixdorf (8810 M35, 8810 M55 etc).

Meanwhile in GDR, the Robotron PCs were made.
Their 8086 versions ran flavors of Unix, CP/M-86 and the DCP - the Disc Control Program, an DOS compatible OS.
Some models had an intelligent PC BIOS with a sophisticated self-test.

Their video sub system was CGA compatible, but also could do resolution/colour-depth close to VGA in 640x480c in 16c.
The graphics controller was better than Motorola CRTC, it was the one used in PC-9801 in Japan.

Emulation of x86 PCs of former East Germany?

The tragedy about East German PCs is that they never got the recognition they deserved.
Even their own people didn't acknowledge them, which puzzles me.
I think it was related to the anger about espionage and Robotron in general.
Also, many Germans in the 80s were technophobic. They feared that computers would take their jobs etc.

It's also interesting that GDR managed to produce an 80286 clone torwards its end, the U80601.
That wasn't that 32-Bit chip everyone praises in retrospect, though. "Just" an 80286.

Fun fact: The Z80 clone made in GDR, the U880, was better than Zilogs!
Why? Because Zilog lied a bit about the specs but GDR devs didn't know that and took them literal.
That's why the tolerances of the GDR Z80 are better. It has a minor bug, though.

Edit: Quote fixed, sorry. 🙁

I wasn't insinuating they weren't lovable. Great write up jo22.

Op, ease post photos.

Schneider Europan XT. Very sexy pos.

I mean it in a loving way.

Of course euro PC's have to be sexy, and cute, and artistic. US PC:s just look mean and growl at you. The kind you don't want to meet in a dark alley.

Haha, yes indeed! 😂

Brings back some memories of the US Super Nintendo vs Super Famicom/Euro SNES.
Fans to this today do argue about the design.

Edit:
SFC..: "konnichiwa! ^^ ❤️"
US-SNES..:"HERE AM I !! 💀"

Seriously though, it's all good. 🙂

Hi again guy
So... Now I'm cleaning motherboard.
Tryed to test PSU and it gives totally shit - 5v is jumping from 3 to 4.2 volts. 12 volts gives same as 5 volts. -12 gives from -7 to -9 volts.
PG gives nothing (upd. Lol, there is no powergood part inside )
I'm not very good at electronic, so could somebody gives advice to me where to find problem.
Also - bios battery gives 0 volts, it is methal hydrid 3-cells battery. What whith could i replace it? Could I use li-ion battery instead?if
Also 2c- if I can't repair psu, what whis I can change it? Now I'm thinking about voltage stabilizer like 7805 and 7812 with some new small power supply (notebook like 4 example).
Thanx for any help

So...
Cleant all MS, chips... Connect to modern atx PSU - and there is no totally beeps...
Isa analyzer chows 41 and C1 codes...

PSU repair is not that difficult but you need to have a proper testing setup. Preferably with isolation transformer but that is not stricly required if you don't try to stick your hands everywhere, and you keep track of your tools. But you should have a ligthbulb in socket, several preferably to change as required. 25W, 40W, 60W and 100W but at least the 100W one. Put it in series with the PSU input, this way any faults on the primary side are quickly caught and don't result in loud bangs and tons of part and PCB damage. Not to mention tripped circuit breakers. On some of the dumber switching mode PSU this can also happen with a short on secondary side, or if enough caps fail and the whole thing goes into random oscillations.

I prefer to repair the PSU but yes, a substitute can be made. In fact you can use a substitute for testing, to figure out if the PSU is a problem. I find the voltages you gave very odd, it's like either the primary or the secondary (or both?) capacitors failed almost completly. This usually doesn't happen. Note, some PSUs can't be tested without a minimum load - for that you can also use lightbulbs. For +12V line use automotive 12V 5W bulb, or 21W if you want bigger load. For 5V line you can use 6V scooter type bulb, 5W should be enough in most cases. If you don't have 6V lightbulbs then 12V 5W will also work as a load. -12V doesn't need a load usually, and certainly nothing more than 5W. It's also usually not very well regulated, anything from -10V to -14V is usually OK-ish.

I use lab PSU with multiple outputs and current limiting to test stuff. It's not cheap (you need at least one with 2 outputs, for 5V and 12V, the -12V is usually only used on serial ports and such on computers from '90 onwards) but the easiest and safest method. I would advise agains using a PC power supply for that, there is no current limit in those, or if there is it will be set so high it doesn't matter. You can end up damaging the PCB and parts on it with one of those.

Deunan wrote on 2025-03-17, 17:21:

PSU repair is not that difficult but you need to have a proper testing setup. Preferably with isolation transformer but that is not stricly required if you don't try to stick your hands everywhere, and you keep track of your tools. But you should have a ligthbulb in socket, several preferably to change as required. 25W, 40W, 60W and 100W but at least the 100W one. Put it in series with the PSU input, this way any

...

Just connect Schneider to atx PSU 5, 12, -12. As I beleive to multimeter - voltage is right.
There is no any life signals...
Found that I don't know why, but onboard video ram is overheated... (41464 modules)
any ideas?

p.s. Does for start motherboard needs 12 and -12 volts?

p.p.s I don't know is it ok, but resistance between 5v and GND is only 15 ohm. Is it ok?

I have fixed 1 p/s by removing it's board from the case, randomly reflowing solder joints on the bottom of the board.

Hi, I've once rebuilt the PSU of my Schneider Tower AT.
Not sure if the Euro XT PSU is similar, though.

From what I can tell, the Tower AT PSU was very unconventional.
a) It generated -5v using two positive 5v lines or vice versa.
b) The diodes were broken. I installed big, oversized 1N4007 or something.
c) I've replaced caps and the power mosfets.

Personally, I would remove everything unnecessary first for testing.
I would install an ISA POST card, with voltage LEDs if possible.

A modern ISA RAM card as a replacement for faulty on-board RAM (LoTech etc).
It has 1MB, which covers everything. - But only install it after the voltages are stable.
Old DRAMs can easily die if their 5v/-5v rail is too high.

Edit: The antique light bulb method is okay,
in modern times I would at least install an RCD switch that disconnects the circuit very quickly if there's a short.

tereg wrote on 2025-03-17, 17:35:

Just connect Schneider to atx PSU 5, 12, -12. As I beleive to multimeter - voltage is right. There is no any life signals... Fo […]
Show full quote

Just connect Schneider to atx PSU 5, 12, -12. As I beleive to multimeter - voltage is right.
There is no any life signals...
Found that I don't know why, but onboard video ram is overheated... (41464 modules)
any ideas?

And that is another reason why I use lab PSU with current limiting. So that if any chips are shorted I don't stress the PCB traces. The 41464 should be +5V only, some older tech DRAMs required multiple voltages and in correct sequence or they would fry. But DRAM chips do fail, even the modern ones, so it's not impossible that you have some bad chips. But if all are getting hot then the issue might be lack of correct drive for outputs and bus fighthing. That is not good if you let that continue for long time, it will kill any still good chips eventually.

tereg wrote on 2025-03-17, 17:35:

p.s. Does for start motherboard needs 12 and -12 volts?

p.p.s I don't know is it ok, but resistance between 5v and GND is only 15 ohm. Is it ok?

Sadly I do not know if this mobo requires +12V, most do not but some do for clock circuits and such. -12V on such system should not be required, although I might be wrong about this too. But -12V is only needed for very ancient MOS chips, serial ports, sometimes for DACs on video and audio cards. On this mobo the logic should not be using it at all.

15 ohms is quite fine. 5V/15ohms = 0.3(3)A. It's actually very low, I would expect the mobo will pull more from 5V rail when running.