Worklog Nintendo Vegas

[YveltalGriffin]

After months and months of procrastination, I've finally begun assembling a prototype of my Wii motherboard redesign, which I'm calling Vegas. The name is an homage to Nintendo's naming scheme for the Wii's chipset (Broadway and Hollywood, both famous hubs of entertainment in the US). I designed the proto board in Altium, referencing both the compendium and additional mobo scans I took. While I tried to replicate the Wii's stackup as closely as possible, I couldn't get the GDDR3 impedances to where I would've liked. Worst case, I can try tweaking the GDDR3's ZQ termination resistor.

This ready and willing RVL-CPU-40 was the donor motherboard. The first step was to desolder the Hollywood and Broadway. I bought some neat BGA hot air nozzles that match the size of the Wii GPU and CPU to make things easier. (Flux added around perimeter of Hollywood after pic was taken)

I'm pretty happy with my workbench setup for this process. The Omnivises, hot air stand, and vac pick-up tool really streamline things.

Next is reballing. The overall process is as follows: clean BGA pads with 63/37 solder, flux, and solder wick; apply thin layer of tacky flux to the bare chip; use reball jig and stencil to apply solder balls; reflow under gentle hot air. The magnetic jig I'm using is pretty good, but it's still challenging to get the chip level and flush with the underside of the stencil. Speaking of stencils, I got an assortment of video game console stencils that included Wii-specific ones. No fooling around with universal stencils here.

After a couple tries, I mostly got the hang of the process and had a sexy reballed Wii chipset on my hands (and solder balls ALL over my workbench). Luckily, I bought fresh GDDR3 for this project, so I didn't have to desolder and reball the original RAM.

Hopefully all these image embeds don't break... Next post will cover assembling the PCB!

 

[Wesk]

 

[YveltalGriffin]

Solder paste stenciling was an absolute nightmare... For some reason, JLCPCB's stencil was warped right in the middle between the GPU and CPU. I eventually managed to get the CPU and GPU pasted properly but had to wipe off the RAM pads and do them separately in a second pass. I've gotten dozens of stencils from JLC and haven't had this issue before so I have no clue why this particular stencil was so screwy. Foreshadowing...?

I placed the GPU, CPU, and RAM and popped it into the reflow oven. A few minutes later and the board was looking pretty good!

Next I transplanted the NAND and AVE from the original mobo. I figured I should rely on the reflow oven's controlled temp profile for the BGAs and do the ICs that are easy to solder by hand manually.

Being the rather lazy person I am, I did not delve into the land of reference designators and Shank's Super Thread to buy a fresh BOM of passives for the proto board. Instead I just transplanted passives from the original mobo. After tacking everything down, I went back over with SMD291 and hot air to get all the joints solid.

Once all the passives were transferred, I put the board into the ultrasonic cleaner for a while. Here's how it turned out:

Unfortunately, here's where my luck ran out (for now). When I checked the voltage rail resistances I found ALL the main rails were shorted together. I reflowed the Hollywood a few times with copious amounts of flux and jiggled it around, but it didn't change anything. Having already taken some glamour shots of the sexy assembled PCB, I desoldered the Hollywood and the short between 3.3V and 1V went away. There must have been some seriously major solder blobbing going on under the BGA for 3.3v and 1v to be shorted together...

I didn't enjoy removing the GPU right after finishing the assembly, but such is life with experimental boards. Debugging is inevitable with projects like this! A 28x28 BGA is no joke especially in the suboptimal conditions of a hobbyist's home lab. Thankfully I can just rework the BGAs onto this same mobo with hot air while keeping the passives, NAND, and AVE on the back.

I think I'll try reballing the GPU with slightly smaller solder balls (0.5mm instead of 0.6mm) to reduce the chance of shorts under the chip. As mentioned above I'm also going to rework the BGAs back onto the mobo with hot air, which should let me monitor the reflow a bit more closely. Once the solderability issues are sorted out and the chipset is on without shorts, I can begin the pre-powerup checklist!

 

[supertazon]

Truely a work of art, the Sistine Chapel of Wii portablizing. Fingers crossed you get the issues ironed out!

 

[ScrambledFrequency]

Holy crap that is nice!
How come you decided to do a custom PCB?
It doesn't look any smaller than an OMEGA trim.
Just out of curiosity, I'm sure you know better than I do!

 

[StonedEdge]

Holy crap that is nice!
How come you decided to do a custom PCB?
It doesn't look any smaller than an OMEGA trim.
Just out of curiosity, I'm sure you know better than I do!

 

[buzzyc]

In practicality sense, all the test pads for BT, USB, Voltage rails would be nicer to work with.
In reality, getting to the point of the Vegas undermines the ease these test pads will bring
But, pretty!

 

[YveltalGriffin]

Yep, a single custom PCB will never be able to beat the OMEGA when it comes to size (especially since OMEGAs "stack" the NAND and AVE under the RAM and CPU.) But it'll open the door to more integrated builds, like a single-PCB portable with regulation/charging, GC+, and direct drive all on one board.

I'll admit it's not super practical-- making an OMEGA is a one-evening job with no reballing required. But Vegas is a fun way to challenge myself and learn new skills, while pushing the hobby a little further. It feels like the inevitable endgame of Wii portablizing.

 

[thedrew]

This is wild, honestly a bit speechless. Everything is just so... perfect. Your hand soldering is a work of art, beautiful.

 

[honigbrai]

If you would put the voltage regulators on the board it might be smaller than omga + voltage regulators

Yep, a single custom PCB will never be able to beat the OMEGA when it comes to size (especially since OMEGAs "stack" the NAND and AVE under the RAM and CPU.) But it'll open the door to more integrated builds, like a single-PCB portable with regulation/charging, GC+, and direct drive all on one board.

I'll admit it's not super practical-- making an OMEGA is a one-evening job with no reballing required. But Vegas is a fun way to challenge myself and learn new skills, while pushing the hobby a little further. It feels like the inevitable endgame of Wii portablizing.