diff --git a/content/post/thinkpad_usb_fix.md b/content/post/thinkpad_usb_fix.md new file mode 100644 index 0000000..b191149 --- /dev/null +++ b/content/post/thinkpad_usb_fix.md @@ -0,0 +1,116 @@ +--- +title: "ThinkPad USB Port Fix" +date: 2019-02-28 +lastmod: 2019-02-28 +tags: ["electronics"] +categories: [] +--- +From the moment that I first had my (_used_) ThinkPad X220, the bottom-right USB +port nearest to the SD card reader had been broken. The pad (_or bolster_) was +missing, along with 3 out of 4 pins having been completely broken off. Needless +to say this required fixing. + + +{{< thumb src="/img/thinkpad-usb-fix/DSC04781.jpg" sub="Final result" >}} + + +# Damage Assessment +The first step was to look at the PCB to assess how this could be, if at all, +replaced. From the outside you could see the damage done. Note the single +pin left and lack of the inner pad (_bolster?_). + +{{< thumb src="/img/thinkpad-usb-fix/DSC04722.jpg" sub="One pin remains" >}} + + +# Measure Twice +Next on the list: measurements. To find a suitable replacement receptacle, I +needed to have the relevant dimensions in comparing to receptacle part drawings +of those available for sale. + +{{< thumbgallery >}} + {{< thumb src="/img/thinkpad-usb-fix/DSC04714.jpg" >}} + {{< thumb src="/img/thinkpad-usb-fix/DSC04718.jpg" >}} +{{< /thumbgallery >}} + +Using generic, non-branded digital calipers I was able to get the following +**approximate** dimensions: + +| Description | Value | +|:-----------------------------|---------:| +| Total Length | _14.7mm_ | +| Total Width | _13.2mm_ | +| Pad Spacing (_along length_) | _9.1mm_ | +| Pad Spacing (_along width_) | _15.4mm_ | +| Pad Width | _1.9mm_ | +
Fig. 1
+ + +# Shopping with Purpose +Using the value above, I was able to track down a USB receptacle[^1] on +Digi-Key[^2] that matched my requirements very, _very_ +closely: + +{{< thumb src="/img/thinkpad-usb-fix/drawing.jpg" sub="Part Drawing" >}} + +## Resounding Comparison +Keep in mind the measured values were an eyeball approximation with a low cost, +unbranded digital caliper. Those values are nearly spot-on. + +| Description | Measured | Part | Difference | +|:-----------------------------|---------:|----------:|:-----------:| +| Total Length | _14.7mm_ | _14.00mm_ | _**+.7mm**_ | +| Total Width | _13.2mm_ | _13.10mm_ | _**+.1mm**_ | +| Pad Spacing (_along length_) | _9.1mm_ | _9.1mm_ | **---** | +| Pad Spacing (_along width_) | _15.4mm_ | _15.7mm_ | _**-.3mm**_ | +| Pad Width | _1.9mm_ | _2.30mm_ | _**-.4mm**_ | +
Fig. 2
+ +The part was ordered, and arrived quickly at my doorstep. Stacked on top of each +other the two receptacles matched up just as I had hoped.. **Fantastic!** + +{{< thumb src="/img/thinkpad-usb-fix/DSC04773.jpg" >}} + +# It's not Over yet +Initial attempts at desoldering the existing (_broken_) receptacle proved +futile. Even with liberal application of flux, high soldering iron temperatures +well beyond typical soldering temperatures[^3], the solder would not flow and +the part would not budge. However, I was able to remove the surface mount pads +though this proved useless later on. + +I quickly realized it did not matter to take care in not damaging a broken part +for removal. Grabbing a nearby set of flush cutters I was able to easily remove +the broken receptacle! _However_, this wasn't **yet** the end. + +The leftover cutoff pins still attached to the PCB proved impossible to +remove. I was able to get all through-hole header pins removed but one. After +having spent about half an hour on it with tweezers, solder wick, a solder +sucker (_desoldering pump_), and flush cutters, I gave up. + +# Throwing in the Towel +It turned out the only way to attach the replacement was to modify the new part +to fit -- _luckily I had ordered two replacements as I broke the first one in +the modification "process"_. Cutting and bending the pins, I was able to get it +soldered on (poorly). There wasn't much wiggle room for cleaning up the +bodged-in replacement; this will have to do. + +{{< thumb src="/img/thinkpad-usb-fix/DSC04774.jpg" >}} + +The part was essentially soldered as a wholly surface mount part, which it is +not. This could have future issues due to a lack of solder-terminated strain +relief in connecting and disconnecting USB devices. In hindsight, I may have +been able to bend the flat pads towards the entry of the receptacle down to +attempt to solder them to the surface mount pads. + +# All the King's horses, and all the King's men +Alas, it was time to put the laptop back together. To my dismay there were +further problems. Due to the modification and forced fitment of the replacement, +the USB receptacle was sticking out too far off of the PCB preventing the +motherboard from correctly fitting. This was quickly solved by using a Dremel +with a low-grit sanding drum and removing material off of the receptacle. The +result was acceptable, and provided a tight fitment into the laptop case. + +{{< thumb src="/img/thinkpad-usb-fix/DSC04775.jpg" sub="End of the journey" >}} + +[^1]: [Molex Part No. 482580002](https://www.molex.com/molex/products/datasheet.jsp?part=active/0482580002_IO_CONNECTORS.xml&channel=Products) +[^2]: [Digi-Key Part No. WM7087CT-ND](https://www.digikey.com/products/en?keywords=WM7087CT-ND) +[^3]: Typical soldering temperatures are around 315-370°C (_600-700°F_)