IBM PS/2 Model 95 case conversion 2020 edition
The final product.
This is a sequel to my PS/2 case conversion from 14 years ago. Between that original article and my most recent changes I had already changed some stuff: cut a hole for a 120mm fan in the motherboard tray, and cut away the bottom drive bays so I could mount a 3.5" drive cage cage out of an old case.
However even with those changes I never used the case much. I found its air intake to be insufficient with only a 92mm fan, and worst of all it couldn't really hold the drives I needed. Although it could now hold more hard disk drives, I still didn't have a bezel for an optical drive. The were gaps between the various parts of the case, which I couldn't really fix. Additionally, my method of driving the Operator Panel display from the parallel port was outdated. Even if my current motherboard still has a parallel port header (which would, in fact, make for a cleaner connection than to an external port), I didn't like the fact that using the parallel port requires special drivers.
In effect there were three reasons I decided to pick up the Model 95 case again: modern PC's don't need many HDD's or an optical drive anymore; access to a 3D printer to create spacers and adapters, or even a drive holder; the know-how to easily put together USB control for the Operator Panel.
The only new metalworking involved was using a spot weld drill bit to remove the stuff that sticks out of the case's door to hold MCA cards and the original centrifugal fan. All that stuff prevented the case from closing with a modern (huge) CPU cooler installed.
The source code and schematic for the Aduino-based USB Operator Panel controller can be found on my GitHub. A CoreTemp plugin is used to show information on the operator panel. I took apart a USB port bracket to be able to connect the Arduino directly to my motherboard.
Wiring loom for the operator panel.
After a while I added a cheap adapter that converts an internal floppy drive to USB... for some reason these adapter use an USB A plug instead of an internal USB header plug but that works fine for my purposes.
3D printed parts
The first part I printed was a holder for the Arduino board, for some reason there's a slot under the operator panel that fits it perfectly. I also printed a clamp that prevents the unused ends of the ribbon cable from touching anything they shouldn't.
Operator panel held in place.
Although I had previously made a hole for a 120mm fan in the rear of the motherboard tray, there were large gaps between the fan and the case and also some holes (from port blanks) around the fan. I designed an adapter to smoothen everything out and hold the fan. This was a difficult part to measure and design due to the complex shape of the tray/case.
Rear fan adapter and Arduino holder. Those plastic pins meant to hold the Arduino quickly broke off, as this was a stupid design without chamfering.
The largest part I designed was a fan holder for a front 140mm fan. The front of the case has plenty of grille area but none of it really lines up nicely with a large fan; this adapter fixes that. As mentioned before, I cut away (and threw out) a couple of the bottom drive bays. Unfortunately that meant I also got rid of the plastic the front bezel clips into. This meant my fan holder design had to incorporate the holes for those clips. I started by designing and printing those separately; matching the shape of the case and getting the clips to properly snap into them took a couple of tries.
The front fan adapter needs accommodate the metal front panel and outer bezel.
Although I don't have the original foot/pedestal for the case, I printed two smaller feet for the case to sit on. This way the case is easier to lift and the front panel is easier to take off. The feet attach to the original foot's mounting points.
STL and Fusion 360 files of the printed parts: 3dprint.zip.
- [done] Need to add dust filters.
- [done] Replace lock as I lack the key. Managed to find a close neough match for the case's lock on AliExpress. I only had to transfer the 'blade' to the new lock.
- [done] Motherboard tray lacks one standoff (near front panel pins, so not that important) - screwed a standoff upside-down into the motherboard as a bodge.
- Nitpick: the power led front panel connector is marked 'reset sw'.
The new lock doesn't look exactly the same and it's half a mm smaller in diameter, but it works fine.
I printed a small frame to hold filters for the front of the case. For the side panels I used magnetic tape, then the filter material, and then electrical tape.
Having a clean look inside the case wasn't very important to me. As for cooling, I think it's Good Enough, it's similar to a traditional somewhat older case, i.e. one intake and exhaust fan, only upside-down. Perhaps the PSU fan should have been at the bottom but this is how I designed the PSU mount back in 2006, and at the time I was using a rear-exhaust PSU.