Building a powersupply for an IBM PS/1 2121...

[Elledan]

I've got this old IBM PS/1 model number 2121 of which the monitor is missing. As you might know, with some systems of the PS/1 series, the PSU was integrated into the monitor.
Since the monitor is missing, I obviously have no way to power this thing.

I've searched for any schematics on the powersupply, or any relevant information, but all I know so far (by disassembling the system), is that the system is provided with power through a Sub-D connector with 25 pins, of which only pins 2, 3, 4, 5, 6, 7, 20 and 22 are used. The rest is probably there for shielding.

Is there anyone here who could provide me with information on the used voltages/amperages on these pins and also how to construct a suitable powersupply? Any other information/tips is welcome as well.

 

[blahblah99]

I dont know much about that ibm model, but are you sure those pins listed are for power? It seems like four of those wires are used for video (r,g,b,sync) and the other four are for power (gnd, +5,+12,-5).. but I might be wrong.

As for the power supply, are you going to be using the 120AC or battery? If your using batteries, Maxim have some nice and simple power supply ICs that require very few external components. And as for the amperage, having a PS that can deliver more than the required amperage wouldn't hurt

 

[Elledan]

<< I dont know much about that ibm model, but are you sure those pins listed are for power? It seems like four of those wires are used for video (r,g,b,sync) and the other four are for power (gnd, +5,+12,-5).. but I might be wrong. >>


Well, it's the only connector on this system which is not used for video (there are already two different sub-D connectors for video), keyboard/mouse (two PS/2 ports) or as a parallel connection (printer). I don't see an icon next to it explaining its function either, so that leaves very few options, no?



<< As for the power supply, are you going to be using the 120AC or battery? >>

I'll be running it off 240 AC (I live in Europe ).


<< If your using batteries, Maxim have some nice and simple power supply ICs that require very few external components. And as for the amperage, having a PS that can deliver more than the required amperage wouldn't hurt >>

Hehe... you're right =)

[edit]: I could post a few pictures if necessary, to clarify things.

 

[RossGr]

Your main problem is finding the pin out of the IBM 25 pin connector. I would bet that info is avialable on the web, I have seen pages and pages of pin outs for all sorts of esoteric connectors so it would surprise me if you can't find it. Once you get the pin out simply use an off the shelf ATX powersupply and make an adapter from the ATX 20 pin connector to the 25 pin configuration which you need. Match the gauge of wire used in the adapter to that used by the IBM system.

You might check the AT standard wire colors to see if that is what is used in this computer.



Good Luck

 

[Elledan]

<< Your main problem is finding the pin out of the IBM 25 pin connector. I would bet that info is avialable on the web, I have seen pages and pages of pin outs for all sorts of esoteric connectors so it would surprise me if you can't find it. >>

I've hunted for such a schematic for a while, but had no luck


<< Once you get the pin out simply use an off the shelf ATX powersupply and make an adapter from the ATX 20 pin connector to the 25 pin configuration which you need. Match the gauge of wire used in the adapter to that used by the IBM system. >>

Good tip! I hadn't even thought about that


<< You might check the AT standard wire colors to see if that is what is used in this computer. >>

Nope, no such luck. The only color used for wires is grey for the ribbon cables, nothing else...

I think I'll go hunting for for a pin out schematic again.

Thanks for your help

 

[RossGr]

<< I've hunted for such a schematic for a while, but had no luck >>



What a drag!, that is the biggest trouble with proprietary systems, then the manufacture wants an arm and a leg for the documentation. GL

 

[Elledan]

<<

<< I've hunted for such a schematic for a while, but had no luck >>



What a drag!, that is the biggest trouble with proprietary systems, then the manufacture wants an arm and a leg for the documentation. GL >>


Tell me about it

Hmm... perhaps someone here has a complete PS/1 system (or just the monitor) lying around and has a multimeter ready?