Worklog The LIGHTNiiNG - BLOCKED

[RedEnergy]

Problem found: ground was shorted to 1.8V, as I thought the problem was under the RAM aind it happened because i tried to reflow it a second time and I moved it too much with the tweezers.

 

[RedEnergy]

Small update but some good news. I managed to make a new working PCB for the display.

There was a mistake on the blue vga line, but nothing strange. From the original board I kept just the VGA in order to use less space as possible. There are also pads for the following buttons: power, menu, +, - and source. This PCB will then be modified a little bit in order to be added on the same board of the Wii

 

[DerErzfeind]

This is really exciting! The same idea actually crossed my mind a couple says ago, but I dismissed it for being too complex Would be great if you get this to work, but I also fear you might have some problems with interference between the traces, inductance, etc., wish u good luck tho!

 

[RedEnergy]

I'm really struggling to understand what am I doing wrong.

I'm testing a new board but still nothing. Something does happen: when powered on, the CPU heats up but the GPU stays completely cold; the screen doesn't even show the usual blue screen, but it does when power is given only to it.
I have a 2 theories and I hope only the second one is right:
1) while doing BGA reflow I remember I moved slightly the RAM, so the problem might be that there might be a short under it
2) looking around on bitbuilt forums i read that flux might cause shorts by itself, so i'm thinking that it might be a good thing to clean the board whit an ultrasound cleaner in order to remove any flux from underneath the BGA components

 

[thedrew]

When assembling my board redesign, both chips would get hot but no display. I measured the current each voltage line was drawing and found improper values. I would check that as well as shorts between all the voltage lines since I have discovered the GPU internally cracks under the heat required to remove the GPU from the original board in the first place, therefore shorts out some if not all voltage lines internally. This is why nobody has been successful with a Wii board redesign. The RAM and CPU can take the heat, only the GPU suffers from this problem.

 

[Viilmo]

When assembling my board redesign, both chips would get hot but no display. I measured the current each voltage line was drawing and found improper values. I would check that as well as shorts between all the voltage lines since I have discovered the GPU internally cracks under the heat required to remove the GPU from the original board in the first place, therefore shorts out some if not all voltage lines internally. This is why nobody has been successful with a Wii board redesign. The RAM and CPU can take the heat, only the GPU suffers from this problem.

The thing is also that Redherring managed to resolder the gpu successfully on a Nintendo Vegas, but it still didn't boot. There must be another thing we're missing (atleast on the Vegas, The Lightiing may not have such a problem).

 

[RedEnergy]

Maybe the broblem might be the fact that the BGA components have to be heated for at least three times:
1) Desoldering
2) Reballing
3) Reflow
What I have in mind right now is to do an other attempt; If one of the components does brake in one of these stages I think they might survive If I skip one or even two of the heating steps.
How to do this?
To skip the desoldering (wich I think is the most stressful part for the BGAs due to the long heating time caused to the high melting point if the original solder) I could try to scrape away the PCB from the back using a rotary tool.
I could even try to skip the reballing process by adding solder balls directly on the PCB and than reflow the components on it. But I have to understand if it is possible to do such a thing.

 

[Stitches]

A belt sander would also work for thinning the PCB off the GPU, but you'd have to be careful

 

[YveltalGriffin]

@thedrew has tried all manner of exotic methods of removing the GPU without stressing it thermally. That includes grinding away the motherboard from behind, both mechanically and with a laser cutter.

Also, both Drew and @Aurelio have cut out the mobo around the GPU to reduce the thermal mass and the amount of heat required to desolder it, to no avail.

@Redherring32 has a proper BGA rework station, so I sent him a Vegas board. He baked a Wii chipset to remove all the moisture, and was able to reball+attach the chipset without dead shorts. My design needed some bodges but Red was more than capable of doing those. Same result: chips got warm, but no signs of life.

So no one has been successful yet, and it's unclear why. It could be that the GPU die attach solder balls simply have a melting point too low for rework and they're shorting under the die. Or it could still be a moisture thing and no one has baked the chipset long/hot enough to prevent cracking/popcorning. Or it could be signal integrity/stackup stuff, though I think that's unlikely.

Working on my own redesign isn't a priority for me right now, but IMO here's what needs to happen for any of the redesigns to move forward:

• Full characterization of a softmodded, stripped down stock mobo or omega trim:
  • current traces of all voltage rails at boot, measured with sense resistors
  • logic analyzer captures of the NAND lines, and digital video lines at boot
  • logic analyzer capture of boot0/boot1 debug port at boot
• Rework of redesigned mobo to include:
  • current sense resistors on all voltage rails
  • test pads for NAND lines, digital video lines, maybe EXI, and boot0/boot1 debug
• Proper temp-controlled reball and rework of the GPU onto new PCB (I think RedHerring's attempt is the best/most controlled yet)
• Full characterization of the redesigned mobo, just like with the original mobo:
  • current traces of all voltage rails at boot, measured with sense resistors
  • logic analyzer captures of the NAND lines and digital video lines at boot
  • logic analyzer capture of boot0/boot1 debug pads at boot

This test plan would allow for a 1-to-1 comparison between a stock mobo and the redesigned one, and should make it pretty obvious if there are hardware issues, if boot0/boot1 are succeeding or not, etc. Hopefully someone has the bandwidth to tackle this

 

[Zini]

Pardon me if I'm saying something stupid, but could you perhaps use a corrosive like nitric acid to delid the GPU? That would at least let you see the inside and see what causes the damage when heat is applied. I've read about people using nitric acid to decap ICs back in the early days of modding. Here is an interesting write-up on it.

I don't know what I'm talking about, really, this was all a result of some casual googling, so if this wouldn't work for any number of reasons that's fine by me. Nevertheless I'm excited to see where this project goes.

 

[StonedEdge]

Understood everyone is excited about the previous post, but please keep this thread on topic. @valderJ Please next time create a new thread if you’d like to post about your project and let’s try to keep this on topic to RedEnergy’s project as per forum etiquette.

Thanks!

ADMIN EDIT: Reaction posts related to the valderJ post have been cleared - Stitches