2016-01-26

Manta MID721QC

Very cheap 7" tablet distributed probably under dozen different brands:
  • Allwinner A33, quad-core A7 running at 1.2GHz with Mali400 graphics
  • 7" 800x480 display with poor viewing angles (I can say that just viewing it in vertical position can give strange impression as left and right eye see slightly different images) and capacitive multitouch
  • WiFi
  • VGA front camera
  • accelerometer
  • Android 4.4.2
  • 512 MB RAM, 4 GB Flash
  • microphone and (poor) speaker
  • micro SD slot
  • roughly 4 hours on battery (WiFi, internet), up to 6 hours (WiFi disabled, minimum brightness, PDF reader)
 I believe this tablet had factory installed trojan - at least I don't think I could infect it just in an hour and such "accidents" are not rare. This must have pretty fresh mutations as VirusTotal says that file was first scanned on 2015-12-12 (https://www.virustotal.com/en/file/401a320b23213932b222cc0afb8c69acb12efb9cbeb1884f0873a581d0192f96/analysis/)
Trojan was embedded in GoogleQuickSearchBox.apk (system application) and required rooting to remove. I believe it was responsible for opening fishy "antivirus" site once or twice and it also tried to install "WiFi Booster" (another malware?).
Case is easy to open with bare hands.
PCB markings: AL-Ax3-Q8-V1.1 2015-01-21
Serial number from sticker vanished just after few hours of light use; nice trick to void varranty
2200mAh cell (still lot of spare space), main board
357090 (3.5mm x 70mm x 90mm) 2200mAh protected cell. It looks like 3575100 (3000-3500mAh) should fit also.
unpopulated: vibration motor?

ESP8089 WiFi (close cousin of ESP8266); FBNL83A51K3BAAWP 32Gb NAND from Spectek

2x K4B2G0846 2Gb DDR3

LPA4890CM audio amplifier; up to 350 mW output power in this configuration, in reality probably 50 mW, might be worth tweaking

'7660 voltage converter (backlight power supply?)

AXP223 power manager



miniature camera (VGA)

8 ohm speaker with no markings

2016-01-21

Lenovo T500

Few notes on Lenovo T500 - in comparison with R500

  • slightly lighter and tinner, yet simingly on pair with durability to R500
  • LCD unit cover has rubbery finish; it feels nicer than hard plastic in R500 but is more susceptible to scratches
  • palmrest, keyboard and bevel above keyboard is virtually identical - one difference is speakers placement which are placed at the top instead of at the sides of keyboard; if feels little more solid under pressure but on the other hand keyboard seems to have less support in the top right corner
  • bottom part is made of metal instead of plastic; while R500 was already very solid it takes it one step further and from my perspective removes small problem with R500 - bottom plastic was easy to damage if using too much torque for the screws holding e.g. palmrest
  • it's easier to find unit with mid/top specification (Penryn, BT, camera) as T500 probably was not even sold with Merom
  • 1280x800 screen is no better than in R500 (quite low viewing angles), although it comes with LED backlight this time
  • same as with R500 it works great with Linux - in fact causing less problems (and these are common) that Windows
    • I had problems enabling bluetooth on Windows - it probably requires installing lenovo bloatware but it worked out of the box with Linux and stayed enabled when switching back to Windows
    • for unknown reason Conexant Audio 20561 muted speaker output (headphone output was fine) under Windows 7 while leaving no clue (i.e. OS did not saw output as muted); pressing Vol+ key on keyboard and/or upgrading driver helps for it although headphone output disappeared from available volume controls replaced by SPDIF (not a big loss)
  • it uses Ultrabay Slim instead of Ultrabay Enhanced - your DVD drive from R500 may not fit into T500

  •  same as R500 it is NOT spill resistant; yes, there are spill drains at the bottom but there is no way in hell water will flow through them instead of frying mainboard
    • there are no spill drains on the keyboard (at least not on mine - neither with R500 nor T500)
    • can you even spot drain holes looking from top?
    • spilled water can flow freely through gaps between palmrest , top bevel and keyboard
  • LCD unit is connected with flex connector instead of bunch of wires
  •  apparently different keyboards (despite being replaceable) can have slightly different construction

Notes from (almost) replacing fan

As original fan started making noises - especially when using in non-flat position - I've bought cheapest replacement. T500 seems to be starting fan even under light loads (CPU temperature less than 50C) but fan is very quiet then. This is original fan, MCF-224PAM05, it seemed that noised were caused by loose bearing:
And this is el cheapo replacement I bought on ebay for $2.69 with direct shipping from China, MCF-217PAM05, advertised as fitting ThinkPad T61 T61P R61 W500 T500 T400:
Both are using 3-pin connector. Although they seem similar new one did not fit too well - it was slightly higher and even after replacing ventilator with "original" (more fins but slightly lower profile) it required some bending (for its credit: original one apparently was also slightly bent). Apart from that its shape is slightly different, so piece of tape was required for sealing. Worst part is, new one was pretty loud right from the start and noises did not disappeared after a weak. Strangely, after switching back to original fan noises disappeared - perhaps cleaning/reassembling was enough.
More photos: