Life on FR4

Recently, I got a used Razer BLACKWIDOW Ultimate 2014 mechanical keyboard with the fancy Razer greenswitches inside. The keyboard looks awesome and I really like the illuminated keys too. I'm not a person who likes the lound, clicking sounds that this switches are make when you press them down but I decided to give it a try. Sadly, the smile in my face went away as soon as I plugged the keyboard in and started typing on it. Every second or third character was doubled or missed on the screen of my computer. Something was wrong for sure with the keys, this issue is called scattering by the way. Actually I know that before I bought the keyboard and this is why I was bought it. There was nothing left, time to investigate the source of this issue. After a few phillips head screws I got inside the keyboard, and I desoldered some of the failed switches. The switch itself was easily disassemblable, 2 securing on each side. The problem was obvious after I looked inside the switch, corrod...

I get another toy for this week.It is working great, exept it is not charging the batteries. Teardown time! Diagnosing the problem allways  starting with visual expection. You can clearly see what is wrong here Something blown up and burned hard The problem is clear, but how to replace a part that never existed in a good condition that is to say, you never seen it, just as a burned piece of silicon.Googling based on the PCB silkscreen get some hits but nothing usefull at all. I dig myself into the device power section, specialy in the charger circuits an I think this is some kind of regulator or protection circuit. Now time to thinking... How this tablets are made? Every manufacturer design his own pcb from scratch? Not of course.Semiconductors like RockChip are popular in this segment.Lot of manufacturer use these kinds of SoC and exist somethink called "solution".A full solution for tablets,smartphones,TVboxs and others. You don't need to searching too hard to...

I love watching videos about reapiring electronics and common problems in this video are faulty ceramic capacitors.This little guys usually sit between Vcc line and ground used as a filter caps. This is great for smoothing voltage rails, but the problem comes up when this caps are failed and causing a dead short to ground. Your device will immediately turn off and never come up again. My Minix Neo X5 had a same problem when I bought it. After I opened up I see somethink strange, somebody tried to fix it by upgrading the fuse just like Tesla Motors did in they batteris . Probably he spend years to researching the right material for this job :D Shorted Fuse Detecting the problem was easy, same as in my previous post about A31s android tablet .Some measurement on diode mode and clear to see that we have a shorted a rail.You can find the WM8326G  datasheet online and usually this datasheet including a reference schematics.This is a good way to start discovering your device subs...

!!!Allwinner A31!!! Quad-Core 64 Bit ultra cheap SoC for everyone!! Yeah sound good...but the truth are awful is some case . First of all do you know about the Banana Pi M2?The Banana Pi M1 (A20) was the killer of the first generation Raspberry pi . After the second generation Rpi was released the Bpi m2 was released too . But where is it ? The Bpi m2 was a huge fail (M3 was changed the M2 very soon) . Nobody care about the A31 SoC linux support . No community,no projects,hack or any interesting thing about this mini ARM board. And what about the android support? Little bit better but not in all case. My new target is a A31 SoC based tablet with nice screen and big battery . But something wrong because I can't turn on.And my journey started here. I took it apart and try to locating the wrong parts.I started on the power rails : Sorted Main Board WorkBench  APX221 is a dedicated Power Management Unit for A31 SoC. You can find a lot of informations  on sunxi linux...

OP3n DOTT ?! WTF ... newest company "from china with love". Promoting nice 8" Intel CPU based tablet and smartphone, both with android. And here is some accessories for their smartphone and tablet,bluetooth headset BT 4.0 Integrated MIC NFC sounds good!Get one and take a part. What's under the hood?The Op3n dott don't want to reinvent the wheel. As you can see he used the well known CSR-8635 module. Limited Datasheet and tools for flashing available on the net,not bad! And what about the sound quality?Not too bad but if you want to get some nice quality tones probably you will be disappointed. Keep in mind this is a 35$ BT headset :D Luckily I have a lot of headphones and headset parts. For example a  pair of sennheiser HD-180 headset speakers,and this is much better that the original ones. The stock speaker The stock speaker Truly integrated speaker by Sennheiser.This was fluid XD? upgraded speaker Now the sound quality ...