Hardware New 3DS XL Y button not working

[CosmicTacoCat]

Hello, I have a New 3DS XL that almost works perfectly fine. The only issue is that that the pressing the Y button does nothing at all. I have another N3DS XL and tried swapping the daughter boards but that resulted in no change. The ribbon cable seems to be fine and has continuity all across it. I have tested for continuity between the test points on the daughter board and the motherboard for the ABXY buttons based on the images I found online attached below. There is continuity for the ABX test points but not for the Y points.
I think the issue might be at the ribbon cable connector on the motherboard or the small component (is it a resistor or cap?) leading to the motherboard's Y test point.

I have seen people solder to these points for making external controllers and I was wondering if soldering a wire between the Y test points on these boards would work.
I'm comfortable with soldering and working on electronic devices but I'd like see if someone more knowledgeable on the N3DS XL could help troubleshoot.

Spoiler: New 3DS XL Motherboard

Spoiler: New 3DS XL Daughterboard

 

[Frutzel]

Hey, from what you've said here it seems that the issue resides on the motherboard side.
Did you use the ribbon cable from the other 3DS' daughter board as well? This way you can make sure that the cable is ok.

Do the pins on the mainboard connector on the side that holds the ribbon cable look ok?
You could try testing for continuity only on the mainboard between the connector (cable side) and the test point. That's gonna be hard and you need to be careful, but maybe you can find out something new.

I doubt that it's an issue with the SMD component you mentioned. The other lead seems to be connected to GND, so it might be a pull-down-resistor or a cap to help with signal conditioning. Either way, even it it's bad, you should still have continuity here.
If you have a multimeter, you can try measuring resistance across the SMD components. That's not really accurate as long as the components are soldered in, but if you compare the results of all 4 buttons, they should be roughly the same. If you're able to do that, you can also try measuring capacitance, depending on your equipment.

Otherwise, it shouldn't hurt to connect a cable between the testpoints and see what happens. If all the other buttons have continuity here, you shouldn't destroy anything electronically. Soldering to the small contact on the mainboard might prove difficult again though.

 

[CosmicTacoCat]

I have tried both ribbon cables but it made no difference.
The connector on the mobo looks fine, at least with the naked eye. I'll make sure and check if the connector and test point have continuity.

 

[CosmicTacoCat]

I am bit worried about skipping over that smd component when connecting both boards by wire, though. Particularly if it's a resistor.

 

[Frutzel]

If the resistor is connected to GND on the other side (you can also measure that by testing for continuity between the pad that goes away from the trace and something that's grounded, e.g. the DC connector housing), it doesn't really matter. Its only purpose is to pull down the voltage to GND when no button is pressed. So you won't do any harm here.
If you're too worried, but have small cables and a small soldering tip, try soldering to the resistor itself. I don't think you have many other options left...

 

[CosmicTacoCat]

I'll give it a go today then.

 

[CosmicTacoCat]

I have performed the repair job and can say that it was a success! The Y button seems to work perfectly now.
Thanks for the help, Frutzel.

 

[Frutzel]

I'm glad to hear that!
Did you just solder in a wire or did you do some more troubleshooting?

 

[CosmicTacoCat]

I only soldered a wire on.

 

[yaum]

I only soldered a wire on.

Thanks for your documentation of some of the test points, I was searching for a documentation of the test points (especially to test link between daugther board and main board). Would you know if it exists somewhere?
I've only found peaople asking for such documentation, or mentionning it (like @Frutzel )
Any feedback would be welcome.

 

[zxr750j]

https://docs.google.com/document/d/1-dCfkwnoIebxSwfW9gZ9NFpktMHbVTEVkIrduLGLTMM/edit?usp=sharing
You can find the most important testpoints here...

 

[yaum]

https://docs.google.com/document/d/1-dCfkwnoIebxSwfW9gZ9NFpktMHbVTEVkIrduLGLTMM/edit?usp=sharing
You can find the most important testpoints here...

Thanks, It'll be useful when I'll be debugging other 3DS XL, but would you have the same for the new 3DS XL? I'll post a thread for my dead n3DS XL, for which I need this.

 

[zxr750j]

I've been one searching. Maybe i'll rip my n3dsxl apart and search them if i've got the time...

 

[CosmicTacoCat]

Thanks for your documentation of some of the test points, I was searching for a documentation of the test points (especially to test link between daugther board and main board). Would you know if it exists somewhere?
I've only found peaople asking for such documentation, or mentionning it (like @Frutzel )
Any feedback would be welcome.

I've tried looking around for New 3DS XL documentation but it's pretty hard to find anything. Its name alone makes googling harder.
Searching for anything directly for the testpads was pretty impossible.

Eventually I started searching for New 3DS XL external controller mods like this one: http://imaginglabo.web.fc2.com/new3DSLL-barabara.html
I found the images included in my first post on reddit: https://www.reddit.com/r/3dshacks/comments/4yx94j/3ds_xl_new_external_controller_build_log_2/

It looks like to use the test pads, you connect them to ground to trigger a button press. The button test pads on the daughter board go straight to the test pads on the motherboard. So I suppose you could ground either test pad to trigger a button press.

 

[plegenda]

Guys, I'm having a very similar situation with the R Trigger (not working)
I tried to understand the supplemented documentation looking for a test point for that button, but I'm a bit confused.
by any chance do you know where the test pads are for "R" in both the mother and daughterboards?

 

[plegenda]

@CosmicTacoCat @yaum @zxr750j
Sorry for the tag, by any chance do you guys know the contact points for the "R" trigger in both the mother and daughterboard?

 

[zxr750j]

No problem @plegenda. I hate to disappoint you it isn't there. Both R and L have no test points. Apparantly you can use the middle pin on the button.

 

[plegenda]

No problem @plegenda. I hate to disappoint you it isn't there. Both R and L have no test points. Apparantly you can use the middle pin on the button.

those are terribly sad news.
Will try getting a burrowed n3dsxl to swap parts and narrow down the issue.
Thanks @zxr750j !