130 lines
5.7 KiB
Markdown
130 lines
5.7 KiB
Markdown
---
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title: "ThinkPad USB Port Fix"
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date: 2019-02-28
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lastmod: 2019-02-28
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categories: ["Blog"]
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tags: ["electronics"]
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preview: "/static/img/thinkpad-usb-fix/DSC04781.jpg"
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---
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From the moment that I first had my (_used_) ThinkPad X220, the bottom-right USB
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port nearest to the SD card reader had been broken. The pad (_or bolster_) was
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missing, along with 3 out of 4 pins having been completely broken off. Needless
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to say this required fixing.
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{{< thumb src="/static/img/thinkpad-usb-fix/DSC04781.jpg"
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sub="Final result"
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alt="Photo showing fixed USB receptacle on ThinkPad laptop" >}}
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<!--more-->
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# Damage Assessment
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The first step was to look at the PCB to assess how this could be, if at all,
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replaced. From the outside you could see the damage done. Note the single
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pin left and lack of the inner pad (_bolster?_).
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{{< thumb src="/static/img/thinkpad-usb-fix/DSC04722.jpg"
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sub="One pin remains"
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alt="Photo showing one pin remaining on a damaged USB receptacle ">}}
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# Measure Twice
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Next on the list: measurements. To find a suitable replacement receptacle, I
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needed to have the relevant dimensions in comparing to receptacle part drawings
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of those available for sale.
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{{< thumbgallery >}}
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{{< thumb src="/static/img/thinkpad-usb-fix/DSC04714.jpg"
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alt="Photo showing front side of USB receptacle on motherboard PCB" >}}
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{{< thumb src="/static/img/thinkpad-usb-fix/DSC04718.jpg"
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alt="Photo showing back side of USB receptacle on motherboard PCB" >}}
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{{< /thumbgallery >}}
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Using generic, non-branded digital calipers I was able to get the following
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**approximate** dimensions:
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| Description | Value |
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|:-----------------------------|---------:|
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| Total Length | _14.7mm_ |
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| Total Width | _13.2mm_ |
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| Pad Spacing (_along length_) | _9.1mm_ |
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| Pad Spacing (_along width_) | _15.4mm_ |
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| Pad Width | _1.9mm_ |
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<center><sub>Fig. 1</sub></center>
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# Shopping with Purpose
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Using the value above, I was able to track down a USB receptacle[^1] on
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Digi-Key[^2] that matched my requirements very, _very_
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closely.
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## Resounding Comparison
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Keep in mind the measured values were an eyeball approximation with a low cost,
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unbranded digital caliper. Those values are nearly spot-on.
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| Description | Measured | Part | Difference |
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|:-----------------------------|---------:|----------:|:-----------:|
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| Total Length | _14.7mm_ | _14.00mm_ | _**+.7mm**_ |
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| Total Width | _13.2mm_ | _13.10mm_ | _**+.1mm**_ |
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| Pad Spacing (_along length_) | _9.1mm_ | _9.1mm_ | **---** |
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| Pad Spacing (_along width_) | _15.4mm_ | _15.7mm_ | _**-.3mm**_ |
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| Pad Width | _1.9mm_ | _2.30mm_ | _**-.4mm**_ |
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<center><sub>Fig. 2</sub></center>
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The part was ordered, and arrived quickly at my doorstep. Stacked on top of each
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other the two receptacles matched up just as I had hoped.. **Fantastic!**
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{{< thumb src="/static/img/thinkpad-usb-fix/DSC04773.jpg"
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alt="Photo showing new USB receptacle on top of damaged one for comparison" >}}
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# It's not over yet
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Initial attempts at desoldering the existing (_broken_) receptacle proved
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futile. Even with liberal application of flux, high soldering iron temperatures
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well beyond typical soldering temperatures[^3], the solder would not flow and
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the part would not budge. However, I was able to remove the surface mount pads
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though this proved useless later on.
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I quickly realized it did not matter to take care in not damaging a broken part
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for removal. Grabbing a nearby set of flush cutters I was able to easily remove
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the broken receptacle! _However_, this wasn't **yet** the end.
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The leftover cutoff pins still attached to the PCB proved impossible to
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remove. I was able to get all through-hole header pins removed but one. After
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having spent about half an hour on it with tweezers, solder wick, a solder
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sucker (_desoldering pump_), and flush cutters, I gave up.
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# Throwing in the Towel
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It turned out the only way to attach the replacement was to modify the new part
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to fit -- _luckily I had ordered two replacements as I broke the first one in
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the modification "process"_. Cutting and bending the pins, I was able to get it
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soldered on (poorly). There wasn't much wiggle room for cleaning up the
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bodged-in replacement; this will have to do.
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{{< thumb src="/static/img/thinkpad-usb-fix/DSC04774.jpg"
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alt="Photo showing new, undamaged USB receptacle soldered on to motherboard PCB" >}}
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The part was essentially soldered as a wholly surface mount part, which it is
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not. This could have future issues due to a lack of solder-terminated strain
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relief in connecting and disconnecting USB devices. In hindsight, I may have
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been able to bend the flat pads towards the entry of the receptacle down to
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attempt to solder them to the surface mount pads.
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# All the King's horses, all the King's men
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Alas, it was time to put the laptop back together. To my dismay there were
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further problems. Due to the modification and forced fitment of the replacement,
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the USB receptacle was sticking out too far off of the PCB preventing the
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motherboard from correctly fitting. This was quickly solved by using a Dremel
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with a low-grit sanding drum and removing material off of the receptacle. The
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result was acceptable, and provided a tight fitment into the laptop case.
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{{< thumb src="/static/img/thinkpad-usb-fix/DSC04775.jpg"
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sub="End of the journey"
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alt="Photo showing undamaged, new USB receptacle inside casing of ThinkPad laptop" >}}
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[^1]: [Molex Part No. 482580002](https://www.molex.com/molex/products/datasheet.jsp?part=active/0482580002_IO_CONNECTORS.xml&channel=Products)
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[^2]: [Digi-Key Part No. WM7087CT-ND](https://www.digikey.com/products/en?keywords=WM7087CT-ND)
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[^3]: Typical soldering temperatures are around 315-370°C (_600-700°F_)
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