Author Topic: Broken socket  (Read 56362 times)

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Offline Shayde

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  • Posts: 88
  • Location: Auckland, New Zealand
Broken socket
« on: Fri, 05 December 2014, 15:21:03 »
My first mechanical keyboard failure; the socket on my Matias Tactile mini has fallen off:



I'd only used the keyboard a handful of times, and it's only a few months old, which leads me to suspect it's just a bad soldering job rather than a fault with the design, although the socket doesn't seem to have any protection against mechanical stress.  For some reason my phone camera makes it look like the housing and pads are rusty; they're not.

Anyway, my question is, does anyone have any ideas how this can be fixed?  The solder pads on the board itself look too small to solder with a standard soldering iron, which seems to put out permanently wiring in a USB cord.  I can't really see how I can reattach the socket as the pads sit underneath it, which mystifies me how they were put on in the first place.  It could be they're just pressure connected and it's the two pins on either side that hold the socket down, in which case I guess I could try sourcing another one of these sockets and try soldering it at those two points, but again it does seem a bit of a weakness if the entire socket is only held on by those two small pieces of metal.  Would this work?

If Mr Matias reads this, if the above doesn't work, do you have supplies of these little boards for purchase, if possible?  I miss the clicky goodness of the Tactile mini.  :))
Collector-of-switches.  Cherry: red, brown, blue, black, grey (linear), green.  Alps: simp./comp. white, comp. blue, Matias.  NMB: white, black.  Futaba: Cherry stem.  Omron: yellow.  Topre: 45g  Various: Apple II+, TRS80 Model 1, C64, Acorn Electron, ZX81 (lol!).

Offline vvp

  • Posts: 858
Re: Broken socket
« Reply #1 on: Sat, 06 December 2014, 05:20:39 »
Is the usb socket surface mount only?
If so then I would tell it is a bad design. Sockets need to withstand significant forces from plugs being pulled to the sides (i.e. in the direction perpendicular to the plug insertion direction). They should use through hole technology to be stronger if there is no other mechanical arrangement which makes sure that side forces from the cable do not propagate to the socket.
If it is surface mount socket and if there is a space on the other side of the PCB then I would replace it with a through hole socket.

Offline Shayde

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  • Location: Auckland, New Zealand
Re: Broken socket
« Reply #2 on: Sat, 06 December 2014, 16:47:05 »
Is the usb socket surface mount only?
If so then I would tell it is a bad design. Sockets need to withstand significant forces from plugs being pulled to the sides (i.e. in the direction perpendicular to the plug insertion direction). They should use through hole technology to be stronger if there is no other mechanical arrangement which makes sure that side forces from the cable do not propagate to the socket.
If it is surface mount socket and if there is a space on the other side of the PCB then I would replace it with a through hole socket.

Yes, it's mostly surface mount, with two small pins that go through the board to hold it down.  It does seem a weak design to me.

Unfortunately I don't think putting a through hole would work as the PCB is multi-layered, so the USB traces don't come through on the other side.  I'm not sure I could even put the same socket type back on there as the USB traces sit underneath the socket, so how the hell they soldered it onto the board in the first place is a mystery to me.

I suppose I could try replacing it with a Teensy.

Thanks for the suggestion though!
Collector-of-switches.  Cherry: red, brown, blue, black, grey (linear), green.  Alps: simp./comp. white, comp. blue, Matias.  NMB: white, black.  Futaba: Cherry stem.  Omron: yellow.  Topre: 45g  Various: Apple II+, TRS80 Model 1, C64, Acorn Electron, ZX81 (lol!).

Offline feizor

  • Posts: 690
  • Location: Melbourne, Australia
Re: Broken socket
« Reply #3 on: Sat, 06 December 2014, 16:51:52 »
Is the usb socket surface mount only?
If so then I would tell it is a bad design. Sockets need to withstand significant forces from plugs being pulled to the sides (i.e. in the direction perpendicular to the plug insertion direction). They should use through hole technology to be stronger if there is no other mechanical arrangement which makes sure that side forces from the cable do not propagate to the socket.
If it is surface mount socket and if there is a space on the other side of the PCB then I would replace it with a through hole socket.

Yes, it's mostly surface mount, with two small pins that go through the board to hold it down.  It does seem a weak design to me.

Unfortunately I don't think putting a through hole would work as the PCB is multi-layered, so the USB traces don't come through on the other side.  I'm not sure I could even put the same socket type back on there as the USB traces sit underneath the socket, so how the hell they soldered it onto the board in the first place is a mystery to me.

I suppose I could try replacing it with a Teensy.

Thanks for the suggestion though!


Probably soldered using hot air.  None of the pads are exposed once the socket is in place?

Offline Hypersphere

  • Posts: 1886
  • Location: USA
Re: Broken socket
« Reply #4 on: Sat, 06 December 2014, 16:57:01 »
Thanks for posting this. I had no idea that the Matias mini used a surface mount to PCB for its USB connector with no strain relief.

I am in the process of designing ways to install a panel-mount micro-USB connector in a vintage IBM keyboard, and I would always provide plenty of strain relief. I intend to use screws to mount the socket inside the keyboard case and then use a strain-relief cable to connect the socket to the controller.

Offline vvp

  • Posts: 858
Re: Broken socket
« Reply #5 on: Sat, 06 December 2014, 17:10:44 »
Yes, it's mostly surface mount, with two small pins that go through the board to hold it down.  It does seem a weak design to me.
Not sure what you mean by two small pins.
It does not matter much whether the small data pins are through hole or not. It would be a bit better if they are through hole but the sheet metal of the shielding matters the most. It should have through hole pins to the other side of the PCB and those should be soldered from the other side.

Offline Shayde

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  • Posts: 88
  • Location: Auckland, New Zealand
Re: Broken socket
« Reply #6 on: Sat, 06 December 2014, 18:47:25 »
Probably soldered using hot air.  None of the pads are exposed once the socket is in place?

No.  I haven't heard of hot-air soldering before.  Interesting, though I wouldn't have thought it'd provide a very good joint.
Collector-of-switches.  Cherry: red, brown, blue, black, grey (linear), green.  Alps: simp./comp. white, comp. blue, Matias.  NMB: white, black.  Futaba: Cherry stem.  Omron: yellow.  Topre: 45g  Various: Apple II+, TRS80 Model 1, C64, Acorn Electron, ZX81 (lol!).

Offline Shayde

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  • Posts: 88
  • Location: Auckland, New Zealand
Re: Broken socket
« Reply #7 on: Sat, 06 December 2014, 18:48:14 »
Thanks for posting this. I had no idea that the Matias mini used a surface mount to PCB for its USB connector with no strain relief.

I am in the process of designing ways to install a panel-mount micro-USB connector in a vintage IBM keyboard, and I would always provide plenty of strain relief. I intend to use screws to mount the socket inside the keyboard case and then use a strain-relief cable to connect the socket to the controller.

You need to go work for Matias!  ;)
Collector-of-switches.  Cherry: red, brown, blue, black, grey (linear), green.  Alps: simp./comp. white, comp. blue, Matias.  NMB: white, black.  Futaba: Cherry stem.  Omron: yellow.  Topre: 45g  Various: Apple II+, TRS80 Model 1, C64, Acorn Electron, ZX81 (lol!).

Offline Shayde

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  • Posts: 88
  • Location: Auckland, New Zealand
Re: Broken socket
« Reply #8 on: Sat, 06 December 2014, 18:52:05 »
Not sure what you mean by two small pins.
It does not matter much whether the small data pins are through hole or not. It would be a bit better if they are through hole but the sheet metal of the shielding matters the most. It should have through hole pins to the other side of the PCB and those should be soldered from the other side.

Hopefully this'll explain it better:



The circled red area are the USB data pin pads.

The circled green areas are the pins that go through the board and are soldered in on the other side.  They're part of the shielding on the socket itself - they're broken off here.

The circled blue area shows another surface area where the socket is soldered onto the board.  But the two shielding pins are the only place that are through-hole.
Collector-of-switches.  Cherry: red, brown, blue, black, grey (linear), green.  Alps: simp./comp. white, comp. blue, Matias.  NMB: white, black.  Futaba: Cherry stem.  Omron: yellow.  Topre: 45g  Various: Apple II+, TRS80 Model 1, C64, Acorn Electron, ZX81 (lol!).

Offline vvp

  • Posts: 858
Re: Broken socket
« Reply #9 on: Sun, 07 December 2014, 06:00:03 »
Ok, if the side pins were through hole then I would say the connector used is at the minimum acceptable strength.

I guess the through hole pins broke somewhere in the middle, the other half of them is still soldered on the other side of PCB. Based on the picture, the PCB does not look damaged much on this side.If so then you can fix this with a good solder iron only. Buy a new USB socket of the same kind, remove the rest of legs from PCB, clean the socket solder pads of solder, add new solder and flux, attach the new socket and heat up its housing so that the middle SMD pad joins. At this moment the signal SMD pads may join too. If not solder them separately. Solder the through hole legs on the other side of PCB. If it is not clear or you have doubts ask for more info in the soldering thread.

You may try to modify the case so that strong side forces on the cable do not propagate to the USB socket.

Offline Shayde

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  • Posts: 88
  • Location: Auckland, New Zealand
Re: Broken socket
« Reply #10 on: Mon, 08 December 2014, 04:35:53 »
Yes, it does seem to be a failing of the design.  I'm not sure what to read into it that Matias hasn't responded to the critique of the design, or whether they have spares for sale.  He's a busy man I guess.

I don't know if the idea of heating up the case to solder in a replacement socket would work to get the data pins to join.  There's an insulator between the casing and the pins of the socket, so any heat sufficient to heat up the socket so solder on the data pins would melt would I think destroy it.  The data pins can't be soldered separately as they'd be underneath the socket when it's placed on the board.  There's no access.  But I appreciate the idea.
Collector-of-switches.  Cherry: red, brown, blue, black, grey (linear), green.  Alps: simp./comp. white, comp. blue, Matias.  NMB: white, black.  Futaba: Cherry stem.  Omron: yellow.  Topre: 45g  Various: Apple II+, TRS80 Model 1, C64, Acorn Electron, ZX81 (lol!).

Offline vvp

  • Posts: 858
Re: Broken socket
« Reply #11 on: Mon, 08 December 2014, 05:17:06 »
Yes, the data pins probably will not join. They may though. It depends how not only the socket but also the PCB heats up from the socket case.

Anyway if at least about 0.4 mm of the data pin pad is sticking out from below the socket then it is enough to solder them separately from the top back side. You just need to reheat each data pad enough to join. You do not need much surface for that since the data pads and pins are tiny. If the socket data pin ends are exposed at the back side of the socket and they are thick enough, it may be enough to heat it up through the data pin itself only.

Otherwise you need hot air or reflow oven. Just ask in the soldering thread. I'm sure you will get a lot of help there.