What precaution to solder those tiny gauge ? how to ?

[repairs]

HI everyone

Im new here.
I use a wheelchair and i drop the joystick from time to time.I use it unattached.That has put stress on the cable protector leading to it.
The protector opened , i put some glue on it i the past , it reopened at the same place and i was careless not to glue it again.

Now i have isolated one tiny blue wire, very close to the joystick that has broken due to the joystick being dropped and cable taking the shock. I would like to solder it back.

I did do some soldering before a bit , trial error. But that joystick cost a lot and i have very little wire space to do errors since the broken part is so close to the joystick.

What do i need to know about soldering such tiny wires? probably precautions are to take.

Also since it broke because of too much pulling on it , what is the best strategy to have a solder that will hold bending cable tension?

The 2 tiny wires dont touch or barely depending if the cable is bent or not so WOuld i be better adding 1 cm of additionnal wire to reduce tension put on the repaired wire?

thanks

i hope you can see my pictures [ Specified attachment is not available ]

[Gyro]

Hi, welcome to the forum.

That's a bit of a mess isn't it. Ideally you would buy a new cable strain relief and re-terminate the entire cable inside the joystick. If you have sufficient slack in the cable, I would strongly recommend this. If there isn't enough slack in the cable, it's difficult to see how to provide enough strain relief for a lasting repair, with the other cores intact it is obviously impossible to reinforce it with layers of heatshrink sleeving.

If you have to make the repair as-is then adding a short loop of low current stranded wire will certainly get you over the problem of 'zero overlap' on the core, there's no need to make it too short. This will make it easier to make the joints away from the other cores and reduce the risk of melting their insulation. [Edit: Twist the wire strands together for secure mechanical connections that don't rely on just solder for strength, it will make soldering quicker and easier too without needing three hands]. The important thing is to work quickly to minimise wicking of solder up the strands under the insulation, this will cause the patch wire to become stiff and prone to fracture. For overall insulation, rubber self-amalgamating tape is probably the best you can do, carried up over the remains of the strain relief.

As I say, completely re-terminating the cable into the Joystick is by far the best method, if you can.

[Swake]

All what Gyro already said.
'solder' is the stuff with a flux core.
Preferably you have additional separate flux to put on the wire. Flux helps a lot to make the solder 'stick' and flow in the individual cores of the wire.

Fix a rope to the joystick that is slightly shorter than the cable. When the joystick drops the rope will take the chock instead of the cable.

[repairs]

Hi, welcome to the forum.

That's a bit of a mess isn't it. Ideally you would buy a new cable strain relief and re-terminate the entire cable inside the joystick. If you have sufficient slack in the cable, I would strongly recommend this. If there isn't enough slack in the cable, it's difficult to see how to provide enough strain relief for a lasting repair, with the other cores intact it is obviously impossible to reinforce it with layers of heatshrink sleeving.

If you have to make the repair as-is then adding a short loop of low current stranded wire will certainly get you over the problem of 'zero overlap' on the core, there's no need to make it too short. This will make it easier to make the joints away from the other cores and reduce the risk of melting their insulation. [Edit: Twist the wire strands together for secure mechanical connections that don't rely on just solder for strength, it will make soldering quicker and easier too without needing three hands]. The important thing is to work quickly to minimise wicking of solder up the strands under the insulation, this will cause the patch wire to become stiff and prone to fracture. For overall insulation, rubber self-amalgamating tape is probably the best you can do, carried up over the remains of the strain relief.

As I say, completely re-terminating the cable into the Joystick is by far the best method, if you can.

Hi,

i have zero experience with cable strain releive. If i do a clean cut of all the wires and black cable protector, remove the tie wrap inside the joystick, will i be able to push the clean cut cable through the cable strain relief?

If not , would drilling the cable strain releif until the clean-cut cable pass through be a solution ? and add a tie wrap inside the joystick. how solid would that be?

is it worth it to buy a new cable strain releif ? how to know wich one to order? There seems to be so many. maybe it is not necessary if i add other stuff over to reinforce?

While i will have my hand in this setup is there something i can add to even make it more solid to prevent futur cable  breaking, at least at that place?

--------------
also the other option of just soldering the blue wire:
What do you think of pouring epoxy or glue or aquaseal on top of the cable strain releif until reaching the part of the cable where the black protector starts again?

Open to ideas.

THanks

[2N3055]

Those strain relief ruber boots can be bought new.

[Swake]

The rubber thingy protects the cable insulation from being cut into by the border of the casing. From the picture I estimate that it will be easy to remove and re-install the cable and also the rubber thingy should it come out.

The tie wrap protects the cable from being pulled out. You have to re-install such a tie-wrap after repair. I'd put two in series, just because I like redundancy.

You could replace the rubber thingy by something like this: https://be.farnell.com/en-BE/pro-power/pp001704/cable-gland-nylon-10mm-14mm-black/dp/2843071
You need to find the right size of course.

[Swake]

link to aliexpress for 2 types of strain relieves. You still need the cable tie on top of this.

https://www.aliexpress.com/item/1005007644577531.html

https://www.aliexpress.com/item/1005006258324577.html

[Gyro]

First things first - DON'T cut all the wires where you show in your picture. You will lose valuable cable length.

Normally manufacturers use molded on plastic strain reliefs, but I guess the chairs are low volume hand manufacture and reasonably customized. Luckily it isn't the case here anyway. That strain relief is known (in the UK at least) as a sleeved grommet, but also known as strain relief grommet, or extended grommet. They are normally specified by panel hole diameter, but will should include a maximum cable diameter too. If you buy one based on the hole diameter in the box, the cable diameter is almost certain to be correct. Yes you can get them from Ali, but you can also get them from your local electronics distributors (presumably Digikey, Mouser etc.). Depending on how quickly you want to get your chair up and running again, an ebay seller with local stock might be your quickest+cheapest option.

Now the cable...

- Yes, if you cut the cable tie, the cable should slide out. The reason I said don't cut the wires where you indicated is that there is probably a significant length of wire internal to the joystick that would otherwise have to come from your remaining cable, once cut.

- You haven't shown a photo of how the wires are terminated inside the joystick. They will either be soldered directly into a PCB, go to a connector, or maybe a screw terminal strip arrangement. If they are soldered into the PCB, the easiest way is to unsolder them and re-solder when you have replaced the grommet. If you are not happy with soldering to the PCB, the simplest solution is to cut the wires a reasonable distance from the PCB and splice them after. Be sure to document (photo) where the wires go anyway. Leave the blue wire attached as it's going to need splicing anyway, just pull it through the remains of the cable and grommet after you remove the cable tie.

- Once you have all of the wires disconnected inside the joystick, you can cut the cable tie and pull out the cable. You will be left with a stub of cable outer on the end, but the wires should pull out of this (slit if necessary).

- You can then remove the grommet and fit the new one. Slide the wires in and push the full cable diameter through the grommet. Push it far enough that you have undamaged portion to (tightly) fit a new cable tie. You should now have plenty of slack available on the wires inside the joystick. Depending on what you did to disconnect them, either resolder or splice to the ends inside the joystick. If you are splicing, make sure you get some heatshrink sleeving to insulate them. The other wires may have been weakened by flexing at the point where the blue one failed, but as long as they're still reasonably ok, they won't be under any further stress once they're inside the joystick housing.

- Finally, add a couple of blobs of glue at the cable grommet inside the housing. One at the cable tie to stop the cable rotating inside the grommet, and another to stop the grommet rotating inside the joystick housing. You might want to put the joystick in your normal use position and adjust the rotation first, before gluing, to make sure you don't have any annoying twist in the cable.


You could probably do with a cable tie or something somewhere on the frame to prevent the joystick from falling to far and getting mangled again. If you post a photo of the wire terminations inside the joystick we can probably advise further, but hopefully I've covered everything.

[Swake]

Another possibility is to put a plug on it.

Something like this:
https://www.aliexpress.com/item/1005002914421465.html

[repairs]

here is the inside

[repairs]

inside

[Gyro]

It's a bit busy in there isn't it! Clearly there is no point in trying to detach the wires from the PCB, the signal ones go to a PCB connector (together with a bunch of other ones) and the thicker Red and Black power ones go off through a ferrite bead to somewhere that I can't see. Luckily you have a nice empty area where the only thing to avoid is the cylindrical bottom of the joystick.

I see two options, depending on whether you are going to replace the extended grommet...

1. Leave the grommet, cut the cable tie but don't cut any of the wires. Just push/pull the cable up through the grommet, including the short blue one (cut away the small bit of cable outer that was under the grommet). Re-secure and then just splice the blue one once it's inside the case. You are going to have some extra slack in the wires to deal with but hopefully you can form them so that they don't get trapped between the bottom of the joystick and the case. Clearly the easiest option, but it means that you don't get as much protection against cable bending where it goes into the remains of the existing grommet.

2. Cut the wires where you indicated. Fit a new grommet push, the cable in and secure, then splice all of the wires. This gives you more protection against cable bending in future but requires more soldering. You will still want to keep the wires inside the housing fairly long, you need to be able to slip lengths of heatshrink sleeving onto the wires before soldering without having the ends prematurely shrink from soldering heat before you can get them over the solder joints.


The Blue and Green wires are a twisted differential data signal pair. You need to end up with them as close together as possible, but twisting shouldn't be critical over such a short length, this means splicing the full length of the Blue wire in option 1 rather than shortening it. You also need to be really careful of the connections between the base and lid, particularly that ribbon. It should be detachable at the PCB connector, but can be fiddly if you're not used to them.

Maintaining best strain relief with a new grommet is clearly better, long term, but certainly wouldn't blame you for picking option 1. Just make sure that the wires are routed so that they don't get trapped under the joystick when you screw it back together.

[repairs]

Ià.


The Blue and Green wires are a twisted differential data signal pair. You need to end up with them as close together as possible, but twisting shouldn't be critical over such a short length, this means splicing the full length of the Blue wire in option 1 rather than shortening it. You also need to be really careful of the connections between the base and lid, particularly that ribbon. It should be detachable at the PCB connector, but can be fiddly if you're not used to them.
à

HI
I dont know what is differential data signal and the importance of it.
 I understood most of what you wrote generally,  but theses sentences i can not fully understand since english I am still learning as yoda would phrase it. à

Why end up with green and blue wires have to be as close as possible, and what as close together as possible meaning.

What about the ribbon, what is the ribbon for you? what about the should be detachable at the pcb? I see that the info your are are trying to convey in that paragraph are not landing in my neurons. To help me , could you use other words to express your ideas about this paragraph? I would like to understand you.

Thanks

[coppercone2]

are you sure you want to modify this? That red wire looks... like it had better days.

That wire looks like the kind of wire you better replace before it suprises you, so I think that cable is pretty much compromised

RIght now its just broken because of a open wire. It looks like that red wire can chew through the insulation and short with another wire, causing a much more serious problem, possibly breaking connected stuff. 

I would just call yourself lucky that the red wire did not short out something important and replace it. Really, the blue wire breaking is helpful because it is a friendly warning signal for you to replace the cable.

When insulation looks flattened like putty, it means its time for the trash can.


That red wire looks thick too, its a power wire that has some current on it. That wire can cause a big problem I think, possibly including cable fire.

[Swake]

The Blue and Green wires are a twisted differential data signal pair.

I dont know what is differential data signal and the importance of it.

Don't worry, keep them together as they are now as much as possible. If you can twist them as they are now, not more, then do it because that is better. If this twisting is too difficult or you cannot do it over the whole length, then don't worry, it will be good enough.

What about the ribbon, what is the ribbon for you?

The white flat plastic length that connects the bottom part to the front part of the joystick is called a ribbon cable. As the name implies, each strip you see in there is just a wire. You probably have some buttons or a display in the front.
This ribbon wire is somewhat fragile. In your specific case I would advice not to remove it. Certainly don't pull on it. It takes a specific procedure to remove and re-install. It is not difficult, but if you have never done it this can be very enervating. We'll explain in detail should it be required. For now it looks good. If during the repair you think this cable became loose or crooked in the connector, then post a picture and we'll help out.

That wire looks like the kind of wire you better replace before it surprises you, so I think that cable is pretty much compromised

It is regular low quality cheap wire. Don't worry, it will be fine.


Go for Option 1 in Gyro's message. Easiest and quickest. If that doesn't work option 2 is still available after that, but I would suggest you look for a local that has some experience with electronics and the right tools for handling this.

[coppercone2]

how is that normal, it looks like its been deformed because of excess pressure, that one picture looks like strands are about to show through lol

[Swake]

No one writes it is normal. Of course it is better to replace everything. But avoiding to replace the entire wire harness is the essence of this thread.

[coppercone2]

A splice to a torn wire is one thing, but heavily deformed wire near a bend is something that should get some serious thought. The only flaw the OP identified is a ripped wire and damaged strain relief, but it looks like the degradation might be substantially worse. I just think the situation might have been appraised incorrectly.

I think it looks like that wire is going to tear open down the middle and expose copper conductor

[tooki]

Given that a wheelchair is kind of essential to you, I’d consider replacing the cable if possible, since there might be other parts of it that are weakened inside where we can’t see it.

What is on the other end of the cable? A connector? Or does it go straight into something else?

[RoGeorge]

Push the cable inside the joystick until the broken region is fully inside the joystick enclosure, then bend/loop a little the rest of the wires (except the broken one, to make the two ends of the broken wire to overlap with each other).

After that, solder the broken wire , or just twist the broken ends together (if you don't have proper soldering tools).  Immobilize all inside, for example with a glue gun, or whatever other method you may find, so to guard the repair point against future cable pulling and bending.

If you don't have any stress relief cover right at the exist point of the cable, maybe enlarge the exit hole a little, and let the wire wiggle (with the zip-tie against pull still in place, and with the soldering point still fixed relative to the joystick enclosure).

[Gyro]

Up till now, the OP has used a 'make do and mend' strategy, and I think, want's to continue that way. It's bit of a shame that they cut away so much rubber (including from the strain relief grommet to expose the wires but there's nothing to be done about that rather than the more difficult option 2. . I'm sure the wheelchair manufacturer would be more than happy to sell them a new joystick, complete with new cable fitted [EDIT: For a price, from the experience of a neighbor who had a similar problem!].  From the photos, the cable clearly isn't designed to be disconnected at the joystick end (a more considerate manufacturer might have fitted a connector there and sold just replacement cables). I'm sure there will be a connector on the other end of the cable where it plugs into the wheelchair main controller box.

As Swake points out, if option 1 doesn't work, then option 2 is still available, as is buying a new joystick and integral cable. If the other wires are still intact and don't have any bare copper showing through the insulation then there isn't anything to loose. The OP has limited technical and soldering skills, so the simpler the repair, the better.


@repairs: Sorry to have used a technical term in regard to the blue and green twisted pair. Just keep them together after repairing the blue wire. It will still be possible to put a few twists in them afterwards to help do this... or a couple of bits of tape. It's really not critical for the length involved.

[repairs]

A splice to a torn wire is one thing, but heavily deformed wire near a bend is something that should get some serious thought. The only flaw the OP identified is a ripped wire and damaged strain relief, but it looks like the degradation might be substantially worse. I just think the situation might have been appraised incorrectly.

I think it looks like that wire is going to tear open down the middle and expose copper conductor

Hello coppercone2, wich wire do you talk about when writing heavily deformed? the blue one?

From what i understand you are saying that even if a wire still has its insulatin colored plastic it can be broken inside?     
If the colerd insultor is still intact does it not force the connection even if some part of the wire are broken apart?

Meaning How often do we see a intact insulating colored tube contain an area where there is absolutely no metal wire touching each other ?
Thanks

[repairs]

i think it is called a redel connector

It seems to be super rare to come by now . Idont know why .

[coppercone2]

the red wire, its supposed to be a cylinder but it looks flattened


What happens sometimes is that when it gets like that, the wire splits open down the middle, and some copper pops out. if two wires do this, you can have a short circuit. A wire insulation can only take so much fatigue before it does something bad. Losing its shape is the first sign.

and when its deformed like that, you have way less thermal resistance, because its messed up and thinner, so a short duration overload that might have just slightly damaged good wire can lead to a full on short circuit if you have deformed wire (lets say a few seconds of gross overcurrent)

All the consideration that the designer made choosing wire with regards to durability and ability to survive various scenarios is effected when the wire is deformed.


It's kind of like finding a crack in glass. Sure it might work, but its weaker, and problems can start from there.

I see it kind of like this. Its a bit better for you because you only have a 12V circuit, but deformed wire + higher voltages = where it is eventually going to start arcing, making it even worse on mains electronics.









And, even if its low energy or even un-energized, wire CAN still split open from just mechanical things unrelated to electrons.


Though, usually the most common thing that happens in this case, is that you see a tiny sliver of copper, its like a hairline fracture, and then this mostly just causes a problem related to water. but you never know

[repairs]

are you sure you want to modify this? That red wire looks... like it had better days.

That wire looks like the kind of wire you better replace before it suprises you, so I think that cable is pretty much compromised

RIght now its just broken because of a open wire. It looks like that red wire can chew through the insulation and short with another wire, causing a much more serious problem, possibly breaking connected stuff. 

I would just call yourself lucky that the red wire did not short out something important and replace it. Really, the blue wire breaking is helpful because it is a friendly warning signal for you to replace the cable.

When insulation looks flattened like putty, it means its time for the trash can.


That red wire looks thick too, its a power wire that has some current on it. That wire can cause a big problem I think, possibly including cable fire.

Hi what seems to be wrong with the red wire? You perceive it as being flat or about to cause trouble? Could you circle where in the pictures it is giving you that signal?