Saturday, December 20, 2008

Another LiveCD Use

One Christmas present for one of our kids is a particular device that connects via USB. When I connected it to my (Fedora 10) computer, I expected it to bring up a file browser showing the files on the devices. No joy.

I try plugging it into Melissa's (Fedora 8) computer. The file browser comes right up. So I think I may have found a regression in Fedora 10. Well, not so fast.

Here's where the LiveCD comes in. I bring up both computers with a Fedora 9 LiveCD I had hanging around. Still, the file browser comes up on Missy's computer, but not mine. So it seems it must be something other than a difference in the OS. The LiveCD served to eliminate an unknown factor in my problem.

Now I just have to figure out more precisely what the cause is. Both machines use the same model motherboard, and other USB devices do work on mine.

Sunday, December 14, 2008

When 3V is not 3V

I thought the battery in my parents' new motherboard was fine. It said 3V on the battery. It read a hair over 3 volts on my multimeter.

Then I did a little research on lithium batteries, and discovered that even though the 'nominal voltage' is 3V, the 'open-circuit voltage' (what my multi-meter was reading) is supposed to be 3.7, on a full charge that is.

In case anyone is wondering, nominal roughly means 'in name only'. In other words, 'we'll call it one thing when it's really another'. For more examples of nominal, see pipe sizes in plumbing, which can be a little mind-boggling for a novice.

Saturday, December 13, 2008

Busted caps

A couple of weeks ago, I brought home a PC to set up for my parents as a dual-boot machine. It had been sitting idle for some unknown amount of time. After cleaning up my work area a little, I get it all plugged in and hit the power button. A couple of fans start up, but no drives spin up, and there is no video. I take it apart to find the motherboard has no less than 9 blown capacitors, some of them leaking. I believe the board was manufactured around 2002, and as I recall, there were a lot of low quality caps floating around in that time frame.

So my parents get a cheap replacement for the motherboard (<$30), and hand it over to me this Wednesday. After installing the new motherboard and a DVD burner, I get the PC set up as a dual-boot Windows/Fedora (10) box. It is almost ready and I should get it back to my parents today or tomorrow.

I may end up taking this old motherboard to try my hand at replacing caps. It should be good practice for my soldering skills, once I get a soldering iron.