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. Note that UPSes and their batteries is [...]

+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 [...]

DCM loses lock on Virtex-4: It’s all about auto calibration

The whole story began when I decided to be kind enough to tell the Xilinx tools (ISE 9.2 in my case) that the Virtex-4 I’m targeting is a grown-up. Stepping 2, to be precise. I added CONFIG STEPPING = “2″; to the UCF file. It must have been one of those moments where I believed [...]

Vintage Tektronix 515A oscilloscope is looking for a new home

I got it when I was 13. Yes, some of us play with strange toys. I had a lot of fun moments with it, but the truth is that even if it worked, it’s not much of use, now that I’ve betrayed it with a young and colorful one. Mechanically, this old scope is in [...]