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Showing posts from June, 2015

Decoding wireless weather sensor data

Being on the hunt for the cheapest wireless temperature and humidity sensors led me to FreeTec  NC-7345-675 - sold by pearl.de at the fair price of 10E, though I might have paid even less for them. The requirements were: multi-channel, have at least 0.5C accuracy and provide humidity readout. Rolling your own can easily cost more than that. The sensors pair with this weather station . The goal is to store all the data on an SBC and provide a nice HTML frontend with long-term statistics and heating automation. EDIT: blogger removed without warning all the newlines from my code, I had to redo some of those Hardware The first step is to open up the sensors and see what we are dealing with. With the main board detached from the zebra display connector, we can see the coil antenna at the top and the wires for the humidity sensor running at the bottom right. Judging by the traces going from the SW-CH part directly into the chip it seems there is no way to force additional c

Essential Windows software for power users

Do you feel efficient enough when using Windows? Here are some pieces of software that I use and have saved me years. Total Commander I've been using this for more than 10 years, think of it as Midnight Commander (mc) on steroids, for Windows. Screenshots of main features here: http://www.ghisler.com/screenshots/en/ It's practically the first thing I install when I need to work on a machine. Scenarios: copy stuff around from one drive/ftp/share to another, queuing (F2) operations along the way view any files (F3) in ascii/unicode/hex, edit them (F4) search in current folder (Alt+F7), much faster than using an IDE for source files archive old files (Alt+F5, Alt+o) and unpack multiple archives (insert, Alt+F9), in background compare directories (Shift+F2), including by content (Alt+c, y) like different GIT repositories diff selected files, including binary/hex (Alt+f, y) virtual folder support for FTP/Samba/nfs shares, adb, ext2fs, deleted files ... virtual folde

Various laptop operations

I had these pictures lying around, they might be of help to someone. So, in no particular order: MSI GT60 2PC mini-review, inside photo and getting the Windows 8 key from BIOS Intel Centrino Advanced-N 6230 SMA socket repair Random Toshiba laptop reflow attempt

Keyboard membrane repair

This is a short article on a lighter note. I got a broken keyboard (from boxes with  DOA stuff) with a few keys that were not working. I've opened the keyboard up and marked the keys that were not working, you can see a slight red marker trace in the picture below: The key circuitry is a sandwich of three flexible plastic layers: top and bottom with conductive traces and a middle one for isolation. Only the bottom one was broken. Using a continuity meter the breakage was traced to an area near the connector. As a heads-up, the measured resistance for this type of traces is 5-10 ohms/cm, so for a strip/trace longer than 20 cm the meter might not beep anymore. I had some silver paste sitting around unused, so I covered the broken traces with that.  Some shaking required.... ...after shaking all the silver flakes/powder should be evenly distributed. I don't think they mention this anywhere. I believe a bottle of that stuff is around 15E for 5ml, but shoul

Reballing adventures - part 2

Thinking that I've had the process in hand, I've tried reballing a PS3 video chip. I'm not sure it was the video chip at fault since the person who gave it to me had attempted a reflow on it, transforming the YLOD (yellow light of death) into a GLOD (green one). Setup was pretty similar to the one in the previous post; started with a light warming (100-120C) of the complete board to provide uniform thermal expansion and remove moisture: However the chip proved to be a beast and my hot air gun was raising the temperature too slowly to be safe.  I began looking for items that are a similar size and shape in order to make a template for the gun. This screwdriver accessory proved to be the best match. The layout was started by wrapping some gardening wire around the magnetizer and holding it in place with some masking tape. Not removing the tape proved to be a mistake when temperatures of 400C were involved. The wired frame was then wrapped in food-grade a

Reballing adventures - part 1

Some time ago I wrote about a reflow I did on a broken laptop: http://hackcorrelation.blogspot.de/2014/01/medion-md97900-laptop-teardown-and.html The unit worked fine for ~6 months, after which it failed again with the same symptom: no video. It sat unused for one year but then I received a PS3 with the YLOD symptom. This prompted me to order a BGA reballing set from eBay and attempt to fix them both. The PS3 reball will be in a part 2 of this series. This is not a guide, just a journal describing the mistakes I've made during the process. The video chip is the plagued NF-G6150 , also used in the HP DV6000. The laptop still has decent performance when paired with an SSD, for today's standards. The area around the chip was masked with Kapton tape: Then 'shielded' with food-grade aluminium: I had a goose-neck-style phone cradle sitting around which provided a stable hands-free holder for the hot-air gun. The chip was painted with a black marke

Inside stuff - Tenvis IPROBOT3 - WiFi IP camera

I got one of these units at a "gadget exchange meeting". The kind where both parties have mostly useless gadgets and they exchange them. Oh, the camera kept resetting as well. Time to void some warranties.

Repairing a wireless Wiimote charger

Out of my eBay 'lucky bags' I got a wireless charger for Wii remotes. I forgot about it for more than one year since I did not have a Wii at that time. It came with two battery placeholders that also replace the battery cover of the Wii remote. I've tested the included batteries and they seemed to still hold charge. The unit would not turn on: it's time to void the warranty on this "Kamikaze Gear Wireless Charging Dock (Wii)":

Inside stuff - Auraton 2020 TX/RX thermostat

I got this pair of items from a colleague, requesting a repair. The units would not bind to each other, or rather, the RX unit (controlling the heating) would not receive anything from the TX unit. The transmitter, pictured below, is quite a nice low-power unit. It contains the temperature sensor and provides a basic programming interface for controlling the heating - based on day of week, hour, vacation mode. The receiver unit plugs into a free outlet, without hogging it: I would like to see more products that take a plug space return it to the user. In this case, this plug would probably take 2 or even 3 spaces on a 45 degree German-style plug. The manual for the unit is hosted here:  http://www.auraton.pl/img/auraton/instrukcje/en/auraton_2020_2020txplus_en.pdf which also provided the "fix" for the radio binding problem.