23 September 2021

REPAIR: Embedded DisplayPort (eDP) LCD Driver

As luck would have it another item was added to my repair que. This time it was my somewhat "sentimental" secondary monitor, which is basically a recycled ThinkPad X260 display

I really loved this thing as it let me have a 1.5 monitor setup, which was super useful for running Altium. So I knew I had to get it repaired ASAP

Identifying the root cause did not take too long. It turned out that the ACDC adapter failed and managed to feed way more than 12V into the eDP driver board, which eventually fried the 12V to 5V switching regulator. Interestingly all this happened over 3 days, as on the first day I noticed a strange smell in the house but could not pin point it's location, on the second day I noticed the screen flickering, and on the third the screen flashed moments before a bunch of magic smoke was released from the eDP driver D:

The 5V regulator and it's footprint was way beyond salvaging, like the FR4 underneath was charred enough to bulge up. So I cleaned up the pads the best I could, measured the typical current draw on the 5V rail, and finally replaced the section altogether with an adequately rated 5V regulator I had lying around. Also I decided to leave the bulk capacitors and feed in the 5V via original inductor to lower the ripple voltage and current

Other Info

The following might be useful to someone:

  • FC3D6T was the faulty 5V, this is a SOT23-6 package
  • 5V rail drew
    • ~350mA when monitor was ON
    • ~23mA when monitor was OFF
  • 12V rail drew
    • ~210mA when monitor was ON
    • ~12mA when monitor was OFF
  • eDP driver is RTD2556_eDP_WS_R10.1 which also goes by
    • B116XAN02
    • M125NWR3
    • LP133WH1-SPB1
    • LP140WH2-TP
    • N156BGE-EA1
    • M06VH00WX2P33Y00001
    • S20180122-1

13 September 2021

REPAIR: Neato D5 LIDAR Motor

A month or so ago our beloved Neato D5 was starting to have sensor issues, as it would either stop vacuuming midway or only after a couple of minutes. So I reached out to Australia Robotic who said that the LIDAR motor was the likely culprit, and were trusting enough to send a replacement for me to fit :D

Disassembling the unit was quite simple, with the only tricky part being the front bumper (which you have to bend quite a bit to remove/place back on)

With everything apart I was able to have a good look at the LIDAR, which turned out to be a pretty neato ;^) assembly. But before I tell you why, here is a good picture which explains how a 2D LIDAR functions

OK so the laser bounces off an object and the reflected light is picked up by the image sensor, simple enough right? Well, above only tells you what's in front. What if we want to know what's happening all around us? To do this you would need to continuously rotate the LIDAR assembly... BUT wires can't rotate indefinitely, so how do we get power in and data out ?_?

The Neato D5 LIDAR solves this by going wireless:

  • Power is bought in via wireless power transfer, likely inductive coupling
  • Data is taken out via an IR emitter/reciever combo

05 September 2021

PROJECT: Japanese Wood Joinery & Kitchen Shelves

Before COVID steamrolled the whole planet, the wife was planning to take a Japanese wood joinery class at a local university. After that plan fell through she found out that the class teacher/sensei offered similar content in an online format, DIY Japanese Joinery Online Video Courses

So we decided to sign up to the class to see if we could incorporate these new techniques to our woodworking projects. I will admit that I was quite hesitant at first as I tend to be quite lazy/efficient with my work; as in, if two pieces of wood can just be fixed together with glue/screws then I don't see the point of using fancy joints. BUT after spending a good month getting familiar with the new tools (as well as the countless weekends slowly sharpening each one) we finally applied what we learned and made a kitchen shelf; and I have to admit that seeing something so modular come together was 100% good vibes for me. So should be fun to figure out other ways we could use these joints ;^)

Anyway, before cutting all the wood I modeled the assembly in SOLIDWORKS, as my monkey brain has trouble with "complex" assemblies. So here is how that looked (ignore the poorly fitted dovetail joints, here I was too lazy to make separate parts):

And here is how the result came out :D