Posts

Repairing a "for parts" Canon 7D Mark II.

Introduction I was recently looking for a replacement for my ageing (ancient?) entry level Canon 600D. I came across a cheap 7D Mark II body (7d2 from now on) that was sold as “broken, for parts only”. This repair was a fun and rewarding experience requiring no spare parts. The Canon 7D Mark II The Canon 7D Mark II is a high-end 20.2 megapixel APS-C size DSLR that was released towards the end of 2014. It is part of their advanced/professional range of cameras and could be regarded as similar to a 5D Mark IV with a smaller CMOS. At the time of release it was positively received. The body I purchased was sold for €180 as “broken, for parts only”. Let’s hope not.

Tuesday, March 4, 2025 | 10 minutes Read

HP 8640B Part 2: Mains input and rectifier board replacement

Introduction 6 years ago I acquired an HP 8640B that needed work (see HP 8640B Part 1: initial state). Over the last few years, I managed to clean up the unit cosmetically, but not dive in to it any deeper. Until now. I recently found some time to work on it again and started looking at the power rails. I knew that (at least) the -5.2V rail had intermittent issues, and had noticed the caps on the AC input needed to be replaced as well.

Tuesday, February 6, 2024 | 8 minutes Read

Novastar MCTRL300 basic control software

Code can be found at the Github repository. Builds/executables are not available but if anyone has use for them, I’d happily create one for you… What? Simple, basic control of brightness and test patterns/mode for the Novastar MCTRL300 (and possibly others, but I don’t have others to test). It does not allow you to configure your screen. It can be used during testing or (I can imagine) to give just this piece of software to a client to let him dim the screen when no technician is available.

Monday, February 13, 2023 | 2 minutes Read

DIY active / high impedance probe design

The “problem” I’ve been wanting to have an high-impedance (Hi-Z) probe for some time now. Up until now I’ve been searching for something like an HP 85024a which comes up on the second hand market from time to time. It would be overkill for my needs, but still nice… :) Recently I came across an old Elektor/Elektuur article from April 2004 titled “Poor man’s 1GHz active probe” by David Jewsbury. Some more research turned up the bachelor thesis of Thomas Hirschbuechler titled “Design of a low-cost 1GHz active probe”.

Wednesday, January 26, 2022 | 4 minutes Read

Unilumin Upad 2.6mm led screen repair

Introduction I regularly repair tiles of Unilumin 2.6mm Upad that have broken pixels. Since the pixel pitch (distance between the center of the pixels) is only 2.6mm, that leaves only about 0.5mm between the pixels. Not enough for soldering with conventional means. To do this, you do require good eyes or magnification as well as an hot air station. 96x96 pixels on a 25x25cm tile Damage by ripped off pixels. Note the distance between the center of the pixels is only 2.6mm. Pixel dimensions are 2.1x2.1mm.

Unilumin-led

Wednesday, December 22, 2021 | 2 minutes Read

Microcode SW error with an Intel 8265 / 8275 (rev 78) wireless card

The issue Multiple times an hour my wireless connection would drop out for a couple of seconds, then come back up. If this happened while streaming media, most often it would not be noticeable because the media buffer would handle the hiccup, but during regular surfing this would lead to disconnects or unreachable pages. Troubleshooting Looking through the dmesg output I found plenty of tracebacks similar to this (MAC address of my router removed):

Saturday, October 23, 2021 | 8 minutes Read

pCloud sync issue

The issue I had this crappy issue with with the pCloud Linux (AppImage) client (version linux-x64-prod-v1.9.7).It would get stuck syncing a “Local sync” folder, where the Preferences screen as well as the CLI would hang at a certain amount of files and size to be uploaded. Troubleshooting Having no logs to go by (and less than useful technical support on their end), it took me quite a while to find the issue. In the end I found the database where I found some clues as to what was wrong.

Friday, October 8, 2021 | 2 minutes Read

Setting up Visual Studio Code for Python development (on Linux)

Update January 2024: I don’t use many of the separate tools for linting/refactoring/formatting anymore in favour of Ruff. Configuration for Ruff has moved is done in my pyproject.toml template I’m still using AutoDocString to ease docstring creation and MyPy for type checking. Introduction The following is a brief guide to reinstalling/setting up Visual Studio Code (VSC) on a new Linux system. The main use is Python development. As such, it is very brief and mostly for my own documentation.

Monday, September 6, 2021 | 2 minutes Read

TiddlyWiki: Adding warning and tip macros

I am a *very* big fan of TiddlyWiki5 (github). I use it to document just about anything I figure out while working on projects, setting up systems, … Anything I would otherwise quickly forget. It makes it easier to add structure to random tidbits of information, and forcing myself to document while I work on something helps to stay focused on a certain goal. I noticed some of the official documentation Tiddlers had options to emphasize tips and (more importantly) warnings, such as these:

Tiddlywiki

Monday, September 6, 2021 | 2 minutes Read

Home Server – setting up ZFS (revisited)

Introduction Finally, after two years of renovations and two children, I am revisiting the idea of a small home server. I don’t expect it to do much: Media server File backup Some docker containers Grafana Possibly pfSense or another firewall Whenever I’m accessing a remote system (even when using SSH in my internal network) I prefer to start a TMUX session. That way, if I get disconnected (for instance) during the middle of a package upgrade, the process just continues and I can reconnect at a later time without issues (if tmux is not yet installed or you’re not using it yet, I highly recommend reading up on it and taking a bit of time to get used to the basic concepts. I used this quick-start a couple of years ago).

Monday, February 8, 2021 | 2 minutes Read

Using MicroPython (PyBoard V1.1) with Visual Studio Code

Warning This still isn’t working as I think it should. Especially the linting and autocomplete still doesn’t work (leaving only the PyMakr module which works partly, in fact). For example: import pyb still does not add autocompletion when typing something like s = pyb.<CTRL + SPACE>. Most likely this is because I used a combinations of tools that shouldn’t be used together. Need to spend more time on this… Intro I’ve recently started using a PyBoard for a project that I am working on. Writing code in an IDE, saving the files, then manually copying them to the board to test them gets tedious rather quickly. If you’re using Visual Studio Code, there are options to do almost everything from within the IDE itself. Getting things to work as they should took a bit of effort and head scratching. What I needed to do is documented below. Links to the sources of my information is at the bottom.

Monday, September 28, 2020 | 4 minutes Read

AEG GHE613CB3c (Ikea Välgjord) dishwasher error 50

See the edits below the text for two more possible causes I’ve encountered with this machine, both causing the same error. This post was originally created on WordPress, where it received a number of useful comments. Until I’ve migrated comments from the Wordpress site, you can find the original post here. Introduction Our Ikea Välgjord dishwasher stopped working last night. When switched on, it would take a minute or so, then begin beeping (three times, then about two seconds of silence). When opened, the display showed error code 50, and the bottom LED blinked.

Ikea Valgjord

Wednesday, October 10, 2018 | 4 minutes Read

Hytera PD365 programming

Introduction I recently acquired a second-hand Hytera PD365 DMR radio. Hours of trying to program the radio learned me that this is a bit of an odd one out in the Hytera range of radios. I spent *a lot* of time trying to connect it to my computer to read out the memory and program it. I found a lot of information spread out on the internet, but lots of it is not applicable to the PD365. You’ll find remarks such as “There’s a different driver for the PD365.” but which one to use isn’t marked. There might be a page dedicated to the PD365, but I haven’t found it.

Monday, September 10, 2018 | 4 minutes Read

HP 8640B Part 1: initial state

Introduction I recently acquired a HP 8640B signal generator. A quick summary of the specs shows why this is an interesting piece of equipment: 500kHz to 512 MHz (option 2 adds a doubler, extending the range to 1.024 GHz) Available power range is -145dBm to +19 dBm, within +0.5dB across the full frequency range Extremely low phase noise (less then -130 dBc at 450 MHz, 20kHz from the carrier) Fine tuning (when in locked mode): >+/-20ppm Integrated counter, switchable between the internal generator and an external input FM and AM modulation Beautifully engineered (but that’s just an opinion) The retail price in the mid seventies was around 12.000 USD (which in 2017 would be about 90.000 USD).

Saturday, June 10, 2017 | 3 minutes Read

HP 8711(A): modifications, tweaks, refurbishing

Introduction I recently acquired a fairly well preserved HP 8711A network analyser. As sold, this is an economy model, offering only scalar measurements, although vector information can be acquired through the HP-IB bus. What makes this unit interesting, is that the hardware is the same as the never released 8712A, which has vector capabilities. Some changes in the bootrom allow the user to “convert” the unit, making it behave like a full fledged VNA.

Monday, November 14, 2016 | 4 minutes Read

Installing OpenVPN on Ubuntu 12.04

Introduction The company I work for has an OpenVPN server running. Recently I wanted to install the client software on my Windows 7 desktop and my Linux laptop. Our IT guy kindly supplied me with a executable to install and configure the client under Windows and a config file and certificates for Linux. Windows 7 worked immediately but under Linux I had to do some extra steps to get it working properly. I’ll document them here for future reference and maybe other people running in to the same issues.

Wednesday, December 24, 2014 | 2 minutes Read

Wireless Tally for JVC GY-HM790 cameras: Part 1

Introduction I’ve been working on my wireless tally system for a while now. Apart from the connection to the camera (for which I want to use a different connector to alter the appearance of the camera as little as possible) it is finally finished. Looking back, this has taken me much more time than I expected. But as this was the first project that I wanted to do in a more professional way instead of just throwing something together that shouldn’t necessarily be a bad sign. I’ve tried to keep revisions of the schematics, board design and code, as well as a clear BOM that can be used as a guideline in the future, should the need arise.

Monday, March 31, 2014 | 6 minutes Read

Wireless Tally for JVC GY-HM790 cameras: Part 2

After lots of troubleshooting my wireless tally project/product is nearly finished. The prototypes have been tested in the field and proven to work as expected. Next up are the finishing touches: etching the boards with the final adjustments, populating them, programming the microcontrollers and fitting everything in the enclosures. An early prototype boards: An early version of the transmitter board. As a size reference: the top left pads are for a micro usb connector.

Tuesday, February 18, 2014 | 1 minute Read

Wireless Tally for JVC GY-HM790 cameras: Part 3

Part number confusion As I am currently working on a project that involves XBee modules for wireless data transmission I had to look for the best type of module. There are a dazzling amount of different versions and plenty of websites that explain the the different lines of modules (Series 1, Series2, Pro vs normal versions,…). It was much harder to match the version and antenna type that I needed with the corresponding part number, and that is what I needed to order the correct one from suppliers such as Element14 and Mouser.

Monday, September 9, 2013 | 2 minutes Read

Panasonic PT-AE100E lamp power supply repair

Introduction I was asked if I could repair a “broken” Panasonic LCD projector. The lamp would start up, flicker for a couple of minutes and then shut down. No error messages where displayed. Light! But only for about a minute or two… The owner had send it to Panasonic to have it repaired but was told that the LPS (lamp power supply) board needed to be replaced, at a cost of €450. As that was too much compared to the price of a similar new projector the owner didn’t want to invest in a repair and decided to give up on the idea of having it repaired.

Wednesday, June 12, 2013 | 2 minutes Read