When an LG’s OLED screen won’t turn on

In case this helps someone out there: I have an LG OLED65B9‬‬ TV screen for four years. Lately, I began having trouble turning it on. Instead of powering on (from standby mode) the red LED under the screen would blink three times, and then nothing. On the other hand, if I disconnected the screen from [...]

Random insights on lead-acid battery theory

Overview This is a collection of insights regarding lead-acid batteries, in particular those sealed batteries that are used in UPSes. Had it not been for my failed attempts to get a decent battery for my UPS, none of this would have been written. It was only when I asked myself why the UPS doesn’t maintain [...]

APC Smart UPS 750 battery replacement notes

Introduction This post continues my notes on Smart UPS 750, three years later, when it was time to replace the batteries (because they barely held for 13 minutes). It should have been simple, but if I wrote this lengthy post about it, there was clearly something going on. I’ve also written a separate post on [...]

+5V voltage feed on HDMI cables and a failing HDMI2AV converter

After quite a while of working perfectly well, the mini HDMI2AV module I have (in the picture above, mentioned in this post) started producing an unstable picture, and in the end a completely garbled one. It took some time to nail down this specific component in the foodchain, because there was also an HDMI splitter [...]

Pairing a mobile phone with VW RCD 510 / Kufatec Fiscon car radio

I struggled with this a bit, and ended up doing it right by guessing. Even though I should have read the manual to begin with. So the procedure is simple (cited from manual, page 7, “Pairing”): Turn the ignition on. Make sure the Bluetooth feature of your phone is turned on. Start the pairing procedure [...]

Sample EDID info from a few monitors (video resolution parameters)

On Linux machines, there’s a command saying $ xrandr –verbose which outputs a lot of information about the display, in particular the EDID information obtained from the monitor. Among others, it’s a detailed listing of the video modes that the monitor is willing to accept. These modes are usually the standard VESA graphics modes, but [...]

Vacuum your CPU: When cooling suddenly doesn’t work anymore

So I compiled a Linux kernel with 8 threads in parallel on my Linux desktop machine, as I always do. The CPU worked extra hard as usual, but lately its temperature began to rise, ending up at 88°C. It looks like a clock gating mechanism kicked in to save the CPU. But hey, this never [...]

Mini DV MD80 thumb camera: Usage notes with Fedora 12

So I bought this $10 mini DV camera on EBay. Since the user’s manual is pretty out of sync with itself and the product (Chinese and English doesn’t match, even by looking at the specification and drawings) I’ve written down some basic howto, in case I need to remember what to do at a later [...]

Nokia 6267 restarting itself and how I got around it

I know, I know. I have a very old cellular phone. But since I have enough electronic toys, I couldn’t care less about turning my phone into one. And it happens to be a good one. Everything was OK until it failed to start. Or more precisely, it started, and then restarted itself. Like this: [...]

ionice. Only that made upgrading worth it.

Copying gigabytes of disk can get the system sluggish. On Linux, the solution is so simple. If process 18898 happens to take control of your disk, just go: ionice -c 3 -p 18898 And you have your computer back. “-c 3″ means class 3, which is idle class. In other words, take the disk when [...]