Hinge electrical connection - an impassioned plea

[codifies]

Hands up who thinks plastic film connectors are a robust and enduring component....!


Every single device I've ever had with these hateful plastic film connectors has failed, they simply are not suitable for a moving connection.


in a device without moving parts it is the one critical weak point


You may have an old laptop that's been kicking around for years, that's thanks to plastic sleeved copper wire usually running most of the width of the laptop.


The length of this wire allows it to twist 120° or more without stress - there is even multi strand wire specifically designed for this type of use.


Physical wear is not the only issue over time these plastic film connectors become brittle especially if exposed to temperature changes...


I'd really love not to need to buy new lcd cabling every few years or so - as a diary replacement for my phone (android calendar don't cut it) its gonna get some stick is that hinge...


I know room is tight but I think it would be really worth it - personally I'd like the pyra to be pried from my cold dead hand after its forth or fifth CPU board upgrade...

 

[levi]

At least you can buy new LCD cables for your Pandora (whenever they're in stock).

As far as I last recall, it's still slightly open what cabling type will be used on the Pyra. The MIPI interface should mean less wires are required, so some more flexible cabling might be employed.

That said, the prototype designs I've seen from ED look like a similar construction to the Pandora's design, which in my experience does wear out with use.

Not sure about any other hinge tech. Not had any other hinged device fail on me for a number of years, since my old Moto phone. All my DSes are still running fine, and laptops have been retired for other reasons. Perhaps there's something fragile about the Pandora's cable specifically, rather than there being something essentially wrong with the tech (unless none of the devices I own that still work use that tech).

 

[rygD]

All my DSes are still running fine, and laptops have been retired for other reasons.

Same here, but maybe we are very gentle with ours.  It seems to me that Nintendo has used much better ribbon cables for handhelds after the DMG-01.  I have been pretty rough at times with disassembled units and I still haven't had a cable die on anything other than a DMG.  My HP palmtop has damage to the LCD cable from batteries that were left in it, probably over 10 years ago, and after I opened it up and cleaned as best I could everything is still working.  I didn't know what to do with that cable since most of the damage is internal, but it still works.  I don't open and close it much, so maybe that is helping.

I am not saying these types of ribbon cables don't have their weaknesses.  I think it was common knowledge amongst the early HP LX users that the LCD cable was one of the weak points.  I am pretty sure anyone who has spent a lot of time around DMG Game Boys has seen columns, or the less common, but irreparable, rows of dead pixels that come from the use of that kind of cable.  I would prefer something more durable for the Pyra, and even to find something to replace the Pandora cable with.  It seems there are certain factors that make certain ones more fragile than others, so it may help to identify those.  With the DMG it is where the cable connects to the display, which it seems the engineer(s) identified, and their fix was to add a cushion instead of redesigning it.

If temperature is a major factor in longevity of that type of cable then it should really be considered, since it seems there might be quite a bit of heat from the SoC.  I am not sure how much that will affect the cable, but it is better to deal with it before it becomes a problem.

 

[Yoyobuae]

Not sure about any other hinge tech. Not had any other hinged device fail on me for a number of years, since my old Moto phone. All my DSes are still running fine, and laptops have been retired for other reasons. Perhaps there's something fragile about the Pandora's cable specifically, rather than there being something essentially wrong with the tech (unless none of the devices I own that still work use that tech).

I would prefer something more durable for the Pyra, and even to find something to replace the Pandora cable with.  It seems there are certain factors that make certain ones more fragile than others, so it may help to identify those.  With the DMG it is where the cable connects to the display, which it seems the engineer(s) identified, and their fix was to add a cushion instead of redesigning it.

My theory is that rubbing between two loops of the Pandora LCD cable is what makes it fail eventually. Here's is a little test of what possibly happens inside the Pandora's hinge as the lid is opened/closed:



That's the old LCD cable from my Pandora which failed, it is worn mostly where the rubbing happens in the above GIF, with a cut across two lanes on the right loop.

 

[rygD]

First, that is very useful, and I appreciate you sharing it.  

Second, I don't know if that is actually how it would move when opened and closed, since it is only "folding" and not stretching.  

Third, regardless of if the above picture is completely accurate or not, this is bad. Very bad.

Fourth, maybe something can be done to protect our poor little self destructive devices.  I think tape might help.

Fifth, I prefer odd numbers.

 

[sepulep]

I wonder if routing the cable externally with an outside connector on the body and the display would not be a good solution. Cable would be short (2-3 cm), flat and sit tight while closed (you could recess it so it doesn't stick out). Once in a while it would fail (get snagged or whatever), but it is trivial to replace, and in principle you could use the connection to connect an extra external display...

 

[levi]

Fourth, maybe something can be done to protect our poor little self destructive devices.  I think tape might help.

I've considered putting tape on the back of my new LCD cable before installing it, but that would make the tape thicker and make the curl tighter. It does seem that on my failed cable, the most obvious damage is on the outside of the curl, so protecting that might be a good idea.
Looking at it again, I wonder actually if the problem is related the the narrow part of the hinge, where the middle hinge goes inside the outer hinge, so it's the narrowest part of its transit. That will likely hold the roll to some degree, and might be forcing too much cable down towards the motherboard as the hinge opens. Although it looks more complicated than that as my cable seems to have failed inside the curls, rather than in the straight bit between motherboard and roll.

I'm going to order a new lid back anyway, when I order a new cable, so I might experiment with smoothing and opening out the hinge on my old lid at that point. I wonder also if I could find a pipe of the right diameter and thickness, filing off the existing hinge/body interface and gluing that in place to replicate the original piece, although there are locating lugs quite close which make fitting it tricky.

As is, that part seems quite smooth, although it does have a fairly obvious seam between the lid outer and inner. It is impressively narrow tough, which I suspect might cause the cable to shuffle through it as it's backed up towards the motherboard connector as the hinge opens. A more sheer, slippy back to the cable might help make that happen with less friction, but adding an extra layer to the cable is almost certainly a non-starter, judging by how tight that roll is.

 

[comradekingu]

There arent that many cables on MIPI, so it could be user replacable. Hoping the connector is standard enough, hard to get one thats easy to work with though.

I was sure you were going to say opto-coupled "sliding" connectors or something crazy.

So you run a cable over to a laser transmitter in one part of the hinge, and a receiver at the other end. The only mechanical wear is on the hinge itself.

And this has to be powered by a inductor field going across the other hinge.

 

[thatgui]

As far as I last recall, it's still slightly open what cabling type will be used on the Pyra. The MIPI interface should mean less wires are required, so some more flexible cabling might be employed.

Hmm and Hmmm

 

[groovechicken]

Having been through the hell of replacing my cable recently, I feel your pain. I had a sinking feeling in my stomach when ED mentioned a ribbon cable for the Pyra in a recent update.

He knows it was a problem, though, and has thought about it a lot, so I can only hope that what he has come up with be more resilient than the Pandora cable. I was hoping for a traditional round cable without ZIF connectors, but oh well.

 

[DrHAX]

I tore apart a 2003 gateway laptop that had a rather genius solution for the cable wear issues. There was a plastic ring the cable was placed into and slid around one of the hinges.. this allowed the cable to simply rotate slightly without any strain on the system. It was the only well thought out part of that laptop...

 

[levi]

I'm not sure that's usable solution for the Pyra, if it's anything like the Pandora. In the Pandora the coil needs to slacken and tighten as the lid is opened and closed respectively, as the distance between the two ends is slightly longer with the lid closed, and there's little space between the hinge roll and the connectors for any slack to be distributed across.