atomic_fungus (atomic_fungus) wrote,
atomic_fungus
atomic_fungus

#7262: Well, that didn't work, not really.

So, had occasion to replace the screen in a laptop the other day.

At work I have an old, old computer which I use for making DVDs and a few other things. I mean, by any reasonable standard this laptop would be a great replacement for Seiren--an older Core i5 processor, vintage 2015-ish (newer than the one in Floristica!), 16 GB of RAM (salvaged), a 250 GB SSD (also salvaged). I mean, for a computer I cobbled together out of parts I salvaged from computers that were being ewasted, it's a pretty fair dinkum machine.

It worked fine until I closed the lid on the cap for a USB thumb drive and broke the screen. I was having a day, and slapped the lid shut as I was leaving my office to go take care of something that somebody thought was a huge emergency, and then realized Shit.....

Anyway I did a little looking around and found that I did not have so much as one computer like this one anywhere, so I couldn't just take the LCD panel out of another junker and put it into this one. I just resigned myself to having to use an external monitor when using that computer, is all.

This and that happened, a couple of weeks passed; I replaced the screen in a user's laptop (she'd closed hers on a pen) and that task got me to thinking about it again. I did some poking around on-line and found out that some parts vendors said that the screen used in the Latitude E7450 would work in the E6450 as well, and it just so happened that I had taken the keyboard assembly from one of my "end of life" E7450s (next stop: recycle bin) to replace a user's keyboard after she slopped some syrupy goo all over the space bar. Since it could not be reused, I sat down with it and took its screen off, tossed the rest into the "ewaste" (recycle) bin, and carried on.

Shortly I had the screen assembly apart. Steeled myself, and then began to disassemble the DVD-making computer, and shortly I had its screen assembly off and disassembled. Pulled the bad LCD, put the good one in (after making sure the connectors matched) and then reassembled the thing. Put it all the way back together, took a deep breath, crossed my fingers, and turned it on.

Big, bright, beautiful Dell logo, no cracks or fissures or leaking liquid crystal--just a perfect boot screen. And I let it go, and marveled at how nice the screen looked. Very nice! But I was pressed for time, so I shut it down and put it away, content that I had fixed it.

Couple days passed, I had some time, so I hauled it down. And when I looked at the screen settings I got a nice surprise. You see, the native resolution for the broken panel was 1388x900, something like that...but the "recommended resolution" for the display now was 1920x1080. No wonder that screen looked so good!

Here's the thing: a laptop is basically like a desktop computer, only more intricate and less standardized. The laptop's display is basically just a monitor. The cable that goes from the laptop's motherboard to the display is nothing more than a basic signal cable, like an HDMI or VGA cable, with a few added lines for power and such. So as long as the connector is the same, as long as the pins in that connecter are mapped the same, you can plug in any damned display panel you want.

...so when the computer started up, after I swapped in the newer LCD, there was a little back-and-forth between the motherboard and the display panel, and they worked out that 1920x1080 was the correct resolution, and the OS quietly configured itself to display that.

But there's more to this story.

You see, the computer I took apart had a webcam in the lid. Turns out that the webcam is this tiny little thing about 1/4" wide, maybe 3" long, and 1/8" thick. And it connects with USB.

Oh, it's not a standard USB cable; it's a 10-position connector of some kind and the wires are incorporated into the display cable, and connect to the motherboard there. But in theory, if you had that cable, you should be able to connect this camera to any computer's USB port.

So I tried it. Had to use the DMM to suss out which wires go where, and had to find a way to strip these tiny, tiny wires (maybe 30 gauge?) but after sacrificing a USB cable and wiring the thing up, I plugged it into the computer...and it saw the thing! It played the noise it plays when a USB device is plugged in.

...couldn't enumerate it, couldn't find a driver, but it sort-of worked even so. The computer recognized that a USB device was connected, anyway.

Now: the thing says it wants 3.3 volts and I connected it directly to the 5V line in the USB cable. That might have zorched the camera module. Or maybe 5v is just overdriving it so it can't communicate, I don't know. Who cares?

At some point I'll jigger up a way to get the voltage down to 3.3 volts and try again. And perhaps I'll come across another camera module; who knows?

It's just fun to fiddle, is all.
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