Friday, January 17, 2014

Windows 8.1 preview to final in-place upgrade

I had to install Windows 8.1 Preview over the Windows 8 installation which was giving me problems. The problems went away but yesterday I got a nice surprise:

This preview version has expired. Please upgrade to Windows 8.1 using the Store. The computer will reboot in two hours and then every hour.

...or something along the lines.

I started downloading the update but then read on some forums that the installation will wipe clean your previous programs and probably settings, only the [useless] apps will remain in place.

Here's how to skip the trouble and perform an in-place installation of Windows 8.1 while retaining all your previous programs and settings. You will need to have a valid Windows 8 product key.

Steps summary:
1. Go to the 'order page with product key only'
2. Download Windows 8 installer
3. Start the installer and cancel after it reaches 1%
4. Download Windows 8.1 installer from the same link
5. Launch the [new] installer and let it download the image
6. Make an installable USB drive
7. Edit USB:\sources\cversion.ini and replace 9458.0 with 9431.0
7. Create USB:\sources\ei.cfg with the content below
8. Launch USB:\setup.exe and perform the in-place upgrade
9. Restore your Windows 8 key / serial number

[TODO, doing these steps myself just now, will add links]

ei.cfg content:

cversion.ini content:

The installer also requested me to manually uninstall the following programs:
  • Sentinel Runtime Drivers - caused by Lightworks. Download haspdinst.exe and run it with the parameters "-fr -kp"
  • N-Trig installer - this is from my drawing tablet. Renaming \Program Files\N-trig to N-trig.old solved this
You need to install Windows 8.1 without a product key because the Windows 8 key will not be accepted.

To restore your key launch cmd.exe in Administrator mode and enter:
slmgr /rearm

Obviously you need to replace the 'X's with your valid key.

Tuesday, January 14, 2014

DSO5062B - "white screen" repair and hack

I have a lot of posts in my backlog that have pictures but no text added to them. Since a lot of them are more than one year old I figured I should take the effort to add the text lest I forget what happened.

There is a common problem with the DSO5062B oscilloscopes in that they get a white screen once in a while and require a power cycle to recover, temporarily. The scope seems to be functioning in the mean time but nothing is displayed.
The same device is being sold under many different name and brandings: Tekway DST1062B, Voltcraft DSO5062B, Zhongce, Protek, PCE (like mine) but it's exactly the same thing save for the splash screen and printed logo.

Here's how the white screen syndrome looks like, see below for the fix:

Medion MD97900 laptop teardown and repair

I've bought a cheap broken laptop on eBay for around 20EUR with the description "turns on briefly the fan and the shuts down, no image".
The laptop was actually in pretty good condition, came with a working battery and charger and RAM, but without any hard-drive.

A quick search on the Internet turned up the fact that these laptops usually die from heat, having inadequate cooling on the integrated video card.

I recovered the laptop by using a makeshift heat shield made from a sandwich of aluminium foil and cardboard an using a heatgun (paint stripper) to slowly heat the chip. A blob of leaded solder was used as reflow indicator, knowing that the leadfree solder melts at higher temperatures and the BGA balls take a while to heat up (being under the chip).
A cheap multimeter was used as a temperature indicator, with the thermocouple pressed against the chip body.
The cardboard started smoking after a while but this did not affect the operation in any way. The actual heating process took around 2 minutes, another 30-40 seconds were used to slowly pull the heat gun away from the board and it was left for ambient cooling another 10-15 minutes.

I won't bore you with stories, I think the pictures below tell all the details.

Node@Home communication protocol draft

I have been pondering on creating a home network of nodes using cheap slaves and a more powerful master. Since the name did not come up in any Google search I settled upon Node@Home.

My idea is to have gadgets spread around the house/perimeter that can report sensor data to a central station and perform certain actions. It will be first used to start the [electrical] heating remotely, check rooms temperature, actuate the blinds on the outside, log the voltage measured by the home-made PSU, start or unblock the Roomba, etc.

I am sure that with creating an affordable master node (based on Stellaris Launchpad or Raspberry Pi) and disposable slave nodes will make everyone want to have these things around the house.

The minimum requirements for the nodes will be a baseline microcontroller (PIC10/12F, MSP430F, <1$ each) and an NRF24L01 radio transceiver (1-4$). The power of the network will be in the protocol requirements and the software.

UPDATE: the draft below is wrong because I assumed broadcasting was possible with the NRF24 units, which is not. I have written a new one in the mean time but I did not have time to implement a proof-of-concept, so I'm not publishing it until it is proven.
However, the payload section will remain mostly as-is.

Here is my first draft for this, loosely based on the BMW IBUS protocol: