First post, by bitslasher
Greetings!
I'd like to get some community feedback on an idea I have, to see if this is something others would find useful (and worth pursuing). I'm posting this on both VCFed and Vogons, since I'm not sure there is total overlap of members.
I have a mixed collection of old PCs, some generic clones, but many are what were called "proprietary" back in the day-- IBM, Compaqs, Tandy, etc.
A common problem that these systems have is what do you do when the PSU fails? All of these old systems have a slightly different PSU designs, at least when it comes to the case and the wiring connections.
I've seen where people have made "adapters" that allow you to connect an ATX power supply to old systems, but that doesn't give you an arrangement that preserves the original machine, or even allows you to operate the machine in an assembled state.
My idea-- what if there was a modular power supply that consisted of modules that allowed standardization/reuse of the complicated parts: The high-voltage and low-voltage sections, the fitting into various different PSU enclosures, etc:
- An AC module. This module takes in 120/240v mains and converts it to DC 12v.
- A DC module. This module takes in the 12v from the AC module and provides /-5v and +/-12v rails, PWRGOOD, etc.
- A backplane module. This module is what brings it all together. The backplane's job is to fit inside a specific computer's original PSU case. So the idea is you'd remove the old PSU guts, and replace it with this PCB. The PCB itself is pretty bare bone. It provides the mechanical adaptation. It has contacts that provide either connection points for external power leads (like for a generic AT PSU), or it provides a connector for whatever weird proprietary PSU connector the original PCB might have had-- think old Wyse, Compaq, IBM systems that used weird plugs or edge connectors to connect. On this back plane are also mounts for two standardized foot prints for the two modules mentioned above. The AC and DC modules. Together these 3 parts would constitute a complete power supply.
- The AC module would connect to the PSU's original external power plug hardware.
- The DC module would connect to the AC module via a high-amperage lead from the output of the AC module (to a connector on the DC module.)
- The DC module would plug into a socket (40-pin connector) on the backplane. This 40-pin connector would have a standardized pinout, and is what delivers the voltage lanes to the backplane, which provides the traces to the connectors which match up to the original PSU connectors.
For the AC module, you identify a off-the-shelf 12v AC/DC power supply that can attach using standoffs. (I've identified at least 2 from different manufacturers.
For the DC module, you would buy or build it, where it is based on an open-source design I've been working on. The idea is that this part is re-usable on any of the backplanes that follow the design parameters.
For the backplane, you would buy or build it, again using an open-source design that's part of this project.
So the idea is that individuals who know how to do these things would contribute their own designs for different backplanes for their favorite PSU. Someone want to fix the flaky PSUs found in IBM PS/2 Model 50/70s? Just design a backplane that fits in the case and plug in the AC and DC modules and you're set. Once a backplane is designed, then being able to have new power supplies for these old computers is a reality, fitting in the original enclosures, preserving the original appearance and function.
To get things started, I will contribute a few backplane designs for my own collection that I would like to have these for:
- IBM AT
- IBM PS/2 Model 90
- Compaq Deskpro (8086, 286, 386 - the original form factor)
- Compaq Deskpro 386/33, 486/25, 386/33L, 486/33L, 486/50L (this is the giant desktop machine that shared architecture with the original SystemPro)
- Compaq SystemPro, SystemPro/LT
- Compaq 286e, 386s, 386e (these all share the same case/PSU design
- Compaq Deskpro /m
The DC module I'm currently designing is intended to provide the equivalent power of a 200W PSU (when paired with the appropriate AC module).
I wanted to make something that would truly be a drop-in replacement for most old desktop power supplies, being able to drive old giant 5.25 hard disks, etc.
The modular design allows additional DC modules to be created that can provide even more power-- think old Compaq SystemPro systems loaded up with giant disks or an IBM PC Server 500 full of drives, etc.
Those types of designs obviously are more expensive build, and seem to be more niche, so that is an area of expansion if this initial approach works well for everyone.
As you can tell I have quite a bit of Compaq systems. They have notoriously bad PSUs-- so you can maybe get an idea of what's motivated this. 😀
I can see future backplanes for:
- Various Tandy Desktops
- PS/2 Models like the Model 50/70, Model 60/65/80, Model 85/95
- Classic Dell, Gateway, Packard Bell, etc.
- Popular clone PSU form factors
- etc...
I thought a cool name for this project could be the "Revenant PSU" -- revenant being a spirit that reanimates a dead body, so that it can fulfil a purpose or finish unresolved business.
Seemed like a perfect name for something that takes sad dead otherwise functional computers and brings them back to life with new purpose. 😀
The name also seemed like it'd work well in conversation. Like someone says "My PS/2 Model 77's PSU died." Then the answer could be, "Just put a Revenant in it." It could work like folks use "Greaseweasel" or "GoTek" or "XTIDE" and know what they're talking about.
My intention is to publish the designs on Github once I have a working v1.0 design. If anyone has experience and expertise in PCB design and circuitry please step up and help me! This is meant to be a project for the community.
Well there's obviously a lot going on here, so I'll stop here and let anyone share their thoughts or ask questions to help me consider things I might have not thought about!
Thanks in advance for your time!
