dataino.it wrote on 2021-07-19, 20:57:

Verax wrote on 2021-07-19, 20:48:

dataino.it wrote on 2021-07-19, 20:29:

I finished testing the circuit and this is the schematic. I would say it works without problems. tomorrow if the heat permits I will do the version on a base (welding with 34 degrees centigrade is torture).

I was wrong to mark the two pins on the previous connection diagram and I corrected it in any case I republish it.

Cool! So it comes out the white wire connected to a resistance is the reset? (If i understand correctly?)
So you don't have any POST issues wit all of this? Like the keyboard is okay for you?

Yes for start the computer manually u need to power on PSU (green cable connected to ground fixed ) and than the reset cable to ground for a little while .

OKay i'll try then 😀

Don't want to hijack the thread, but would just like to say thanks for the power connector pinouts provided here. Just helped me immensely to resurrect my PCS-11, it's original PSU failed today - couldn't get it to start back up again like I did at the weekend.

Soon I'm going to replace the PSU with one of those Pico ATX supplies, or maybe a mini ITX PSU and complete a proper repair job.

But for now, to get it back up and running again I've simply borrowed a small 12V DC-powered ATX power supply from a Thin Client and fitted it into the original Olivetti PSU casing with a cheap ATX-AT converter cable with the plugs cut off and joined to the original ribbon cable:

Note the non-standard DC connecter from the Thin Client. Not the neatest of jobs, but it is only temporary and most importantly it is working! I've had to remove the Floppy Drive for now, so that I could fit a temporary Molex extension cable and also I haven't added an AT-style power switch yet, which I'll probably mount at the back in the gap.

I forgot to connect "Power Good" though and yet the PC doesn't seem to care?

PTherapist wrote on 2021-07-19, 22:47:

Don't want to hijack the thread, but would just like to say thanks for the power connector pinouts provided here. Just helped m […]
Show full quote

Don't want to hijack the thread, but would just like to say thanks for the power connector pinouts provided here. Just helped me immensely to resurrect my PCS-11, it's original PSU failed today - couldn't get it to start back up again like I did at the weekend.

Soon I'm going to replace the PSU with one of those Pico ATX supplies, or maybe a mini ITX PSU and complete a proper repair job.

But for now, to get it back up and running again I've simply borrowed a small 12V DC-powered ATX power supply from a Thin Client and fitted it into the original Olivetti PSU casing with a cheap ATX-AT converter cable with the plugs cut off and joined to the original ribbon cable:

Note the non-standard DC connecter from the Thin Client. Not the neatest of jobs, but it is only temporary and most importantly it is working! I've had to remove the Floppy Drive for now, so that I could fit a temporary Molex extension cable and also I haven't added an AT-style power switch yet, which I'll probably mount at the back in the gap.

I forgot to connect "Power Good" though and yet the PC doesn't seem to care?

Yes I was checking the connections from the photos and it would seem that you connected what for me is the reset to the white cable or am I wrong ?.

dataino.it wrote on 2021-07-20, 05:31:

Yes I was checking the connections from the photos and it would seem that you connected what for me is the reset to the white cable or am I wrong ?.

You are correct, I connected the -5V to pin 22 as per the pinout in the pic. I didn't connect Pin 21 at all and the PC doesn't seem to care.

Everything seems to be functioning ok, I only have an Ethernet card in the ISA slot and that has been working fine too.

The only slight drawback to the replacement PSU, is the now non-operable power button on the front. But for me, that button has never worked on the original PSU anyway, all it ever did was to trigger a relay that would lock the keyboard and turn on the orange LED at the front. Pressing it again would unlock the keyboard and turn off the LED. I never did understand why a "power" button would act simply as a keyboard lock 🤣.

dataino.it wrote on 2021-07-19, 20:29:

I was wrong to mark the two pins on the previous connection diagram and I corrected it in any case I republish it.

Ah, so white RES wire is reset input after all, as I thought. I mentioned that mobo might not properly boot with just the power applied if there is no proper reset signal, so that's why I suggested to try a switch there. A simple button is even better now that we know for sure the input must be pulled low briefly. There are some reset signals that require a positive pulse.

Anyway, I still think the brown STB is not meant to be connected to PWR_GOOD. There really is no need for that if there is a separate reset line coming through PSU. I might work with PWR_GOOD since it outputs +5V but I doubt that was intended. Too bad we don't have a working original PSU to check anymore - although tracing some connections and parts on the PSU PCB would probably help figure that out. I think it's some sort of standby power (or standby signal) as the name suggests.

I do have a working PCS 33 PSU, which powers my PCS 11 just fine. The motherboards are identical save for the CPU (25MHz vs 33MHz) and associated crystal oscillator.

PTherapist wrote on 2021-07-20, 10:08:

You are correct, I connected the -5V to pin 22 as per the pinout in the pic. I didn't connect Pin 21 at all and the PC doesn't seem to care.

I would disconnect the -5V and put a button there, good chances are that even with some protection resistor (which might not be there) the -5V is stressing some logic input quite a lot. If it's some easy to replace TTL chip it's no big deal short term but I would hate to fry the chipset inputs... Plus you might not get a poper reset on power-on every time.

As for STB, I mentioned it might be for RTC. While there is a battery after all, it is a coin cell, so will drain quickly (back in 386 days CMOS logic in LSI chips was quite leaky, unlike the 4000 series chips there were very slow on the other hand). That being said unless this PC was to be connected to mains all the time, the PSU would be unpowered anyway. So I think it can be left unconnected if we can't figure out what it really does.

paradigital wrote on 2021-07-20, 10:30:

I do have a working PCS 33 PSU, which powers my PCS 11 just fine. The motherboards are identical save for the CPU (25MHz vs 33MHz) and associated crystal oscillator.

Do you still have a working PCS 11 PSU? Or can you maybe investigate what the PCS 33 PSU does with the STB line? And/or have you noticed any unusual fast draining of the RTC battery when the system is not connected to mains? Fast would be, say, 6-12 months with a fresh battery.

Deunan wrote on 2021-07-20, 10:31:

I would disconnect the -5V and put a button there, good chances are that even with some protection resistor (which might not be there) the -5V is stressing some logic input quite a lot. If it's some easy to replace TTL chip it's no big deal short term but I would hate to fry the chipset inputs... Plus you might not get a poper reset on power-on every time.

Actually I just realised I made a dumb mistake anyway, due to not checking -

The white -5v wire is coming from the AT side of the ATX-AT adapter, but the ATX PSU has no -5V so it isn't actually connected to anything. Probably a good thing, I won't reconnect it.

Verax wrote on 2021-07-19, 20:46:

OKay thank you i'm going to get a POST CARD now, just to see if something happends who knows? […]
Show full quote

PC@LIVE wrote on 2021-07-19, 20:21:

I use a POST CARD (see photo), but there are various models, the cost varies from a little (€) to higher figures, even if it is […]
Show full quote

Verax wrote on 2021-07-18, 22:39:

YEs very old indeed. :) I don't really know sorry, i'm not a specialist sadly i am a really beginner in all of that. :-/ […]
Show full quote

YEs very old indeed. 😀 I don't really know sorry, i'm not a specialist sadly i am a really beginner in all of that. 😒

So you think i should get a POST CARD? Okay i'll take a look then, do you have a model to recommand?

Thanks! I'm trying to understand the whole thing and take everything one by one, and now things are getting close, it may be the Keyboard Controller that's failing. And so the post it stopping on that and can't go further. But i'm not 100% sure.

I invite you to read all of the message from the first page if you want a detail understanding of the situation and how it evolved. 😉

I use a POST CARD (see photo), but there are various models, the cost varies from a little (€) to higher figures, even if it is quite similar (or the same, there are professional ones but they cost a lot), the one that I bought it years ago it is very cheap.
It is mainly used to display the Bios error codes, if for a reason the card does not start, no code is displayed.
So if the PC does not start you do almost nothing, if instead it starts up and freezes, you can see from the codes what could create the problem, it also has LEDs from where you can see if the circuits of the various voltages are ok.
At the moment I haven't read the first few pages enough to figure out what's wrong with your PC, but from the last few posts I understand that there is a problem with the power supply.?

OKay thank you i'm going to get a POST CARD now, just to see if something happends who knows?

If you want a quick review on what's not working with my PC, here we go:
Basically the PC seems to had a failed PSU, the transformator is dead, and so it didn't start at all.
So i took another "normal" ATX PSU and solded the cables so the PC can at least "start" electrically speaking.
It worked, the only thing is that nothing happends on the screen, it detects the HDD, etc. but when the keyboard is connected all of the Green LEDs stay on forever and the PC doesn't do anything.

I was recommanded to change some electolyte components on the motherboard, which i did, nothing changed as well.

After some verification, it could be the Keyboard controller that has a problem somehow. Maybe it's the chip itself or maybe another problem that i haven't found yes.

I took off the BIOS Chip and the Keyboard Chip and clean them properly with some contact spray but nothing changed.

So here you have it, that's where i am actually. 😀
I'm still investigating, i've bought a new Keyboard controller Chip and i will see what's happening.
I'm also going to try few tricks i've been told here before, like trying to have a manual reset with a resistance.

If you have any idea on what i should test, please let me know! 😀

A Ok, I think they have advised you well, so you have to wait for the new chip and see if it solves the problem.
For the failed power supply, you may be able to fix it, but if you have no idea what is wrong, it is easier to replace it with a good one.
From what you write it looks like the bios starts up, but hangs before displaying anything on the screen, so it is possible that the POST CARD will tell you what may be bad.

PC@LIVE wrote on 2021-07-20, 19:57:

A Ok, I think they have advised you well, so you have to wait for the new chip and see if it solves the problem. For the failed […]
Show full quote

Verax wrote on 2021-07-19, 20:46:

OKay thank you i'm going to get a POST CARD now, just to see if something happends who knows? […]
Show full quote

PC@LIVE wrote on 2021-07-19, 20:21:

I use a POST CARD (see photo), but there are various models, the cost varies from a little (€) to higher figures, even if it is […]
Show full quote

I use a POST CARD (see photo), but there are various models, the cost varies from a little (€) to higher figures, even if it is quite similar (or the same, there are professional ones but they cost a lot), the one that I bought it years ago it is very cheap.
It is mainly used to display the Bios error codes, if for a reason the card does not start, no code is displayed.
So if the PC does not start you do almost nothing, if instead it starts up and freezes, you can see from the codes what could create the problem, it also has LEDs from where you can see if the circuits of the various voltages are ok.
At the moment I haven't read the first few pages enough to figure out what's wrong with your PC, but from the last few posts I understand that there is a problem with the power supply.?

OKay thank you i'm going to get a POST CARD now, just to see if something happends who knows?

If you want a quick review on what's not working with my PC, here we go:
Basically the PC seems to had a failed PSU, the transformator is dead, and so it didn't start at all.
So i took another "normal" ATX PSU and solded the cables so the PC can at least "start" electrically speaking.
It worked, the only thing is that nothing happends on the screen, it detects the HDD, etc. but when the keyboard is connected all of the Green LEDs stay on forever and the PC doesn't do anything.

I was recommanded to change some electolyte components on the motherboard, which i did, nothing changed as well.

After some verification, it could be the Keyboard controller that has a problem somehow. Maybe it's the chip itself or maybe another problem that i haven't found yes.

I took off the BIOS Chip and the Keyboard Chip and clean them properly with some contact spray but nothing changed.

So here you have it, that's where i am actually. 😀
I'm still investigating, i've bought a new Keyboard controller Chip and i will see what's happening.
I'm also going to try few tricks i've been told here before, like trying to have a manual reset with a resistance.

If you have any idea on what i should test, please let me know! 😀

A Ok, I think they have advised you well, so you have to wait for the new chip and see if it solves the problem.
For the failed power supply, you may be able to fix it, but if you have no idea what is wrong, it is easier to replace it with a good one.
From what you write it looks like the bios starts up, but hangs before displaying anything on the screen, so it is possible that the POST CARD will tell you what may be bad.

Honestly, my PCS11 with the post card does not display any code even if starting, it is now disassembled and I can not make a video, will it be a defect of the motherboard?

dataino.it wrote on 2021-07-20, 20:52:

Honestly, my PCS11 with the post card does not display any code even if starting, it is now disassembled and I can not make a video, will it be a defect of the motherboard?

No, and that is also why I didn't recommend POST card in this case. This is an OEM PC, unusual one too, it's BIOS is most likely custom and might not output any codes - or not on port 0x80 that's used on typical PCs.
The POST card is not completly useless, you can still use the LEDs to check for missing voltages and the RESET signal status on ISA bus.

dataino.it wrote on 2021-07-20, 20:52:

PC@LIVE wrote on 2021-07-20, 19:57:

A Ok, I think they have advised you well, so you have to wait for the new chip and see if it solves the problem. For the failed […]
Show full quote

Verax wrote on 2021-07-19, 20:46:

OKay thank you i'm going to get a POST CARD now, just to see if something happends who knows? […]
Show full quote

OKay thank you i'm going to get a POST CARD now, just to see if something happends who knows?

If you want a quick review on what's not working with my PC, here we go:
Basically the PC seems to had a failed PSU, the transformator is dead, and so it didn't start at all.
So i took another "normal" ATX PSU and solded the cables so the PC can at least "start" electrically speaking.
It worked, the only thing is that nothing happends on the screen, it detects the HDD, etc. but when the keyboard is connected all of the Green LEDs stay on forever and the PC doesn't do anything.

I was recommanded to change some electolyte components on the motherboard, which i did, nothing changed as well.

After some verification, it could be the Keyboard controller that has a problem somehow. Maybe it's the chip itself or maybe another problem that i haven't found yes.

I took off the BIOS Chip and the Keyboard Chip and clean them properly with some contact spray but nothing changed.

So here you have it, that's where i am actually. 😀
I'm still investigating, i've bought a new Keyboard controller Chip and i will see what's happening.
I'm also going to try few tricks i've been told here before, like trying to have a manual reset with a resistance.

If you have any idea on what i should test, please let me know! 😀

A Ok, I think they have advised you well, so you have to wait for the new chip and see if it solves the problem.
For the failed power supply, you may be able to fix it, but if you have no idea what is wrong, it is easier to replace it with a good one.
From what you write it looks like the bios starts up, but hangs before displaying anything on the screen, so it is possible that the POST CARD will tell you what may be bad.

Honestly, my PCS11 with the post card does not display any code even if starting, it is now disassembled and I can not make a video, will it be a defect of the motherboard?

In fact, as they suggest here, it could depend on the BIOS, and if it is not one of the usual ones (AMI, Award, etc ...) it could happen that an error code is not displayed.
However, if it had been obtained by Olivetti by translating and adapting one for 386, it is not certain that you do not see some error code.
Sometimes it happened to me that some cards did not start, and the card shows - - in the display, but this can happen for example with a low battery.
But when it displays - - I notice that the keyboard LEDs are flashing and that the floppy is showing a boot sign (this can also happen with the HD LED flashing).
I don't know what fault your PC has, if you can summarize I could try to understand where the problem may be, but first you need to understand if all the voltages are ok.
If it is a power supply problem, you can try to fix it, but first check the lines (if they are ok), in case finding the faulty line it should not be difficult to fix.
To check them you need a tester, the black lead goes to ground (black wire), the red lead from time to time on the various voltages (+ 5V, + 12V etc.), the tester would set it on ohm x1, note the values ​​and you put them here, obviously if you find 0OHm you have to look for where the short is.

Good evening 😀

So, i've just got my POST card as someone mentionned i should try it out to see what happends, so here we go the result :

https://youtu.be/w4_A1e9XX14

AS you can see nothing really happends, unless all of the leds are on except for the "CLK" one which is off. No numbers or letters nothing.

Next stop for me , i'm going to try the reset technique which someone previously suggest to do with a SPDT switch and a 100 ohm resistor, i'll see what happends then and i get back to you guys! If you still got any other suggestions you think i should try, please be my guest!

Verax wrote on 2021-07-23, 20:12:

Good evening :) […]
Show full quote

Good evening 😀

So, i've just got my POST card as someone mentionned i should try it out to see what happends, so here we go the result :

https://youtu.be/w4_A1e9XX14

AS you can see nothing really happends, unless all of the leds are on except for the "CLK" one which is off. No numbers or letters nothing.

Next stop for me , i'm going to try the reset technique which someone previously suggest to do with a SPDT switch and a 100 ohm resistor, i'll see what happends then and i get back to you guys! If you still got any other suggestions you think i should try, please be my guest!

The reset signal is locked (and the computer) . Try to put it to ground via a resistor .

dataino.it wrote on 2021-07-19, 20:29:

I finished testing the circuit and this is the schematic. I would say it works without problems. tomorrow if the heat permits I will do the version on a base (welding with 34 degrees centigrade is torture).

I was wrong to mark the two pins on the previous connection diagram and I corrected it in any case I republish it.

Hello, you mean like the electric circuit you did?

So basically i just add a resistor between the white wire to what? The "SPDT switch" and then i use the button to see what happend?
Sorry for all of the questions but i'm a total beginner so i'm kind of lost, i prefer to ask 😀

So here it is the complete circuit, do i understand everything correctly?

Yes can work , no problem for any questions.

dataino.it wrote on 2021-07-25, 18:58:

Yes can work , no problem for any questions.

Ok thank you i'm going to test then 😀

Incorrect diagram.

The power good signal is held high till PSU internal detection of their outputs stabilizes then power signal is pulled low through a low value resistor to ground and held there as long as computer is on.

So:

Diagram correctly done is like this:

positive 5V through a 470 ohm resistor to limit current to power good signal when held low and is pulled high when switch is open. And a switch between Power good to ground through 10 ohms resistor. This switch grounds the power good signal when switch is on. That it.

Resistors are there to prevent excessive current and good idea to have cheap resistor burn out if there's a accident than the hard to replace chipset.

Another way:

Power good grounded via 220 ohms resistor to ground. Momentary push button between power good and 5V supply via a 100 ohms resistor. Turn on the PC and push the button once to reset the computer. Also serves as reset button too.

Cheers,

Hey again, so i tested with the previous diagram :

And so nothing happends, no new noises, still nothing on the screen, nothing new.

https://www.youtube.com/watch?v=M8XXzh3Ls38