Keeping the case as original as possible - 03/05/18 - PCB Arrived !

[melka]

Hi everyone,

First of all, sorry for my english as it is not my native language.

Like most of you, I've been a fan of the G5 case design. I started about a year ago to work on my mod, it's not yet completed 100% but it's been running fine for around 10 month now.

I've been running a hackintosh since 2013, a pretty standard config for the time :
- Gigabyte GA-Z77X-UD3H
- Intel Core i7 3770K
- 16Gb Ram
- Cooler Master Hyper 212 Evo
- BeQuiet 750W PSU

Some upgrades I added over the years were SSDs and a better GPU (currently running a GTX 750Ti, but will soon be replaced by a 960 since I can have one really cheap).

It's an old build, but it's still running great and I rarely feel I should upgrade. Maybe someday when I have cash laying around...

After seeing all the case mods around the Internet, one thing I was sure I didn't want to do was to cut the case. Instead, I decided I would keep it as original as possible and build some parts to adapt an ATX motherboard to this case.

I won't bore you with the disassembly pictures we've all seen hundreds of time. Once the case was striped down, it was time to make a simple CAD model of the compartment in order to see how I could fit the mobo. I measured the position and height of the existing motherboard mounts and added them to the CAD file.

I then added a standard ATX motherboard for reference to get a rough idea of where and how it could go.

Next step was to make sure everything would fit, so I went onto grabcad to find 3d models of all the connectors, headers, components, etc... I could find to make my virtual mobo as close as possible as the real one.

And then the components. The person who modeled that GTX 980 : thank you ! I've put this GPU in the CAD project just to have dimensionnal references to a huge graphics card in case I want to upgrade some day.

It was then time to do some real work. I modeled a bunch of plastic parts to be 3D printed. Those part would be screwed to the existing posts on the G5 case and would "deport" the holes to the ATX standard placement.

For the PSU, I removed the insides of the G5 PSU and transplanted the circuits from my BeQuiet PSU (using small plastic parts as with the mobo). I was able to reuse the original power connector without a problem. I then drilled the PSU case to keep the 120mm fan from the BeQuiet PSU.

I also made a 2x2.5" tray to go in the original HDD caddy.

I tried wiring the front connectors, I wasn't able to get audio working, and the USB plug was doing weird things. I'm guessing it's a grounding issue since the motherboard is only grounded via the ATX connector, not the screw holes, so I plan on getting a small grounding wire between one screw hole and the chassis.

I don't have any picture of the case with the components inside, but I'll soon be working on phase 2 : getting the backpanel working. I'll take pictures then.

Right now, I have wires hanging from slots holes, but I want to reuse the original USB / Audio / Ethernet connectors. I made a PCB in Eagle CAD based on the original G5 motherboard to get the placement right. I then rerouted the connectors to standard 0.254mm pitch headers in order to directly solder cables to them. On the other side of the cable, I'll be using 90° connectors.

 

[Subtle]

This looks very impressive so far. I'm looking forward to seeing some photos of the real thing!

 

[macnb]

Great 3D images and engineering skills.
Awaiting 3D to real component photos.

What materials are you planning to use for the standoff and PCI I/O bracket ?
Have are going to manage air flow through the chassis with he graphics card blocking the flow ?

 

[melka]

@macnb : I printed the parts in PLA and had no problem. Air flow hasn't been a problem for now, but I'm using a smaller GTX750. I also installed 2 x 92mm BeQuiet fans in the original back fan housing. If the need ever arises, I have a housing for a 140mm fan that can be printed and installed on 2 standoffs that I didn't use to attach the mobo, that would put this fan in front of the mobo and just next to the front grill.

 

[melka]

So today I went ahead and etched the PCB

Here it is all cut and drilled, next to the original piece of motheboard

The fit seems pretty good, I haven't soldered it yet and I have to check in the case before going any further, but I'm confident

 

[melka]

And here it is inside the case, the fit is pretty good despite some misalignment. Some of those can be worked out by wiggling the connector before soldering, but for the airport and bluetooth antennas, I guess my holes were misplaced. Oh well, it will work that way.
(And sorry for the dusty case guys :/ I haven't cleaned the computer for several months and it's quite dusty here. I'll clean it in the next couple of days, you can be sure).

 

[guillelopez]

That it's a fantastic way to have the original back plate. I love it

 

[melka]

So, I finally found some more time to play with this. The PCB I etched was way too hard to solder carefully, and I decided that I wanted to use the motherboard headers for the ports as much as possible.

My motherboard has headers for USB2, Front Audio and S/PDIF out.

After a bit of googling, I redrew a schematic and came up with a new board.

I couldn't find any reference to a standard ATX header for ethernet, so it's just wired to a header. I'll have to cut a cable and solder female dupont headers to it or crimp an IDC cable, and plug the other side to the RJ45 port on the motherboard.

The USB / FW400 / FW800 headers are wired identical to the corresponding ATX headers, as far as I can tell. USB2.0 pinout seems to be the same on all motherboards, but I'm not 100% sure for the Firewire headers. I don't have any Firewire capabilities, and I doubt I'll ever need it, so I might not solder the header on the PCB, but at least it's routed.

Here comes the interesting part : audio. For the S/PDIF, I only have output on the motherboard. Some other models might have an input as well. Pinout seems to vary a lot between makes and models, but most S/PDIF brackets I could find have a transceiver (the plug) and a cap to filter out noise, nothing much. Being an optical connection, we need +5V to power the LED inside the transceiver. Some motherboard have this +5V on the SPDIF header, some don't, so I added a solder jumper to select the power source : either from the S/PDIF header, or from the USB +5V line.

For the 3.5mm jacks, I was tempted to just solder wires directly from a cable and plug the other end behind the motherboard. I don't really plan on using the front jack on the G5 case, so I could use the AC97 / HDAudio header on the mobo. The difference between AC97 and HDAudio mostly comes from the kind of plugs. The original G5 jacks on the back panel are normally closed jacks, so it's not possible to use (at least not easily) the HD Audio capabilities. I wired the audio header on the PCB as an AC97 plug, with a bit of EMI filter according to Intel's doc.
http://www.formfactors.org/developer\specs\a2928604.pdf
There are some solder jumpers there too : 4 jumpers are used to bypass the EMI filtering if not desired. 2 other jumpers are to connect or disconnect the jack shield from the GND plane in case ground loops are a problem.
If I ever want to use the G5 front panel, I can still solder female headers on some cables and plug them behind the mobo.

I'll think about it a bit more, especially since seeing this post, and then I'll send the Gerber files to get some PCBs made with Elecrow.

 

[melka]

A small mod to the board : I added a connector and power regulator to the board to be able to plug one of the iMac Bluetooth Module model 820-1696-A. Congrats to JeffBurg for the initial experiments.
I'll have to desolder the female connector from a dead iMac motherboard, though, seems to be a QT8B0101 from FoxConn, but it's hard to find a reseller.
However, the Molex 53307 & 52467 connectors seem to be good replacement plug and receptacles if needed : pitch and width seem to be almost the same, and I could desolder and replace the FoxConn plug on the module without too much trouble.
Also added : another USB header + solder points if you want to experiment with plugging an IR receiver or other weird stuff.

 

[laptopleon]

Impressive work and very well-documented on the technical details. Thanks for the insights. I'm a little confused on how the completed, inside of the case looks like though, because there is no overview photograph. Can I ask a few questions?

1) the 3D drawing shows a CPU-cooler that has it's airflow pointed to the back, but the GPU airflow is pointed up. Is that because you can choose the direction of the CPU-cooler yourself? Is this not fixed by the design of ATX-cards?

(This is probably a n00b-question but I have never build a PC and I have no PC around to compare with.)

• It looks from the 3D drawing that the GPU-card airflow is bottom to top.
• It looks from the photo that the CPU cooler airflow is front to back (of the case).
• PSU is not visible but the airflow usually goes top to bottom (and can leave the case front and back underneath the PSU-cover)

I'm looking into a G5 case build myself. That's why I wonder:

2) Why not turn the motherboard 90º counter clockwise? Then the cables and the card would have more room, and not so tight on the PSU cover. Also, the airflow of the card and CPU would be more in line.

3) Exactly what PSU did you use: The be quiet! Power Zone 750W, the Dark Power Pro 11 or the Straight Power 11 750 W?

4) I noticed that several G5 builds left out the original fans. Did you use any case fans or is the case cooled enough as it is by the CPU/GPU/PSU fans? Does the PSU fan provide extra airflow / cooling that in the original case was provided by the front and back fans?