Life on FR4

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...

Probably you allready hear about intel low power system on chips like intel z37XX and Z8XXX family.Powerfull little beast with Android or/and Windows on top of it. I have some device powered with z3537F Soc and I like it.And here come CHINA and poor software engineering.I upgraded my operating system and my BIOS was corrupted! What a blame! So no image no blinking led nothing just black screen. What can you do? Reading chinese forums to bring back your BIOS from usb OR flashing the right BIOS back to your flashchip. You know what this is mean :D ... Turn on your iron! MeegoPad T02 Flash chip sitting and waiting for flahing on the right bottom side.This is an 8Mbyte super fast SPI flash memory and it is supported by the FlahRom utility. I desoldered the chip because I dont know it is inSystemProgramabel or not.It is requred 1.8V logic levels so I can't hook up to bananaPi direcly. And as I said I used my Bpi to flashing the chip but any SPI capable programer can handle the j...

BGA is not the best package ever for hobbyest.Small pads under the chip make really hard to work with it.But if you  get challenged this can be interesting adventure. Here is the situation, I get a Nexus 7 (2013) main board in my hands. Sadly the eMMC was corrupted and of course not work. This is why I'm holding in my hands :D Looking the eMMC specs it is an SDCARD with 8bit bus, same protocol for communication, nothing too complicated and luckily exist something called 1bit mode. In this mode the chip is using only 1 bit to transfering data.So you need to breaking out only 6 pins. 2 type of power ground of course CMD pin for command or data flag Clock for synchronous operation Data0 for transferring data My eMMC is type 4.5 so I can use 3.3V for logic levels.Be carefull! eMMC 5 and up support only 1.8V logic levels. Turn on your iron and let it flow! Wires soldered on the eMMC uSD card reader and eMMC are connected After soldering and gluing everything th...

How many plug-unplug can be made on a HDMI connector while it is operating correcly? What can I say? Sadly, no more on my Odroid C1. I used a cheap MictoHDMI to HDMI adapter on my HDMI cable and this is what cause the problem.I think the pins inside the connector simply lap each other and this cause a dead sort inside the SoC HDMI transreceiver. I tried to swap the connector for a new one, I tried to swap the cable but I never see valid video out of odroid any more :( Desoldered uHDMI connector