Printer Partout #3 - Yet Another One

Yes, I have yet another printer part out. It was in the "Take a part, leave a part" pile at my maker space so I decided to take a part and restock their hot glue supply in return. I really only needed the scanner light, but I wanted to save everybody the trouble. Basically, this is a very similar printer to the one I last parted out, but this one has wireless capabilities. So we're going to take it apart and see what's running it. Everyone else can have the neat stuff like the motors and whatnot. I don't care about that bit. I just want to see the cool stuff.

This is the HP Photosmart C6380 All-in-one printer. Again, very similar to the last one. The routine is fairly similar too: just look for screws, undo the screws, and remove plastic. There were quite a few more plastic clips than I imagined there would be. This certainly presented a challenge, but I certainly didn't want to destroy the whole thing. At the end, I wanted the printer to be relatively intact with the parts I wanted being the only vacancies.

It was hard, almost like surgery, but I got the stuff I wanted out of the printer out of the printer.

Let's look at the logic board first. This is the largest logic board I've seen come out of a recent printer. Still, it's not home to many ICs. We'll go through the big ones here just for fun.

The biggest chip - the CPU - is a what I can only assume is a custom ARM processor by STMicroelectronics. The number on it is 1825-0217 although it's kinda hard to see because half of the numbers got wiped off with the removal of the plastic protector. A search for this chip on Google by just the number comes up with many results, but none have any information on the chip itself. But judging by the big ARM on the chip, it's an ARM processor of some kind. Next to it is a Elpida EDD5116AFTA-6B-E DDR SRAM; this one is 512Mb. Nothing special about it as far as I can see.

You will also find some flash memory on the board. I couldn't find much on the chip, but everything points to Spansion Flash Memory. Then you have an expansion card with a BCM4326 that does the wireless stuff. This also looks like it's an ARM chip, using ARMv7 architecture.

Now let's move on to the scanner light. We'll discard the drive motor because it's useless for what I want to do with it. Now we have an RGB bar. And it's bright. Very bright. Perfect for the Game Console project. I had one from the printer I parted out before but I accidentally blew the red on it, so I went and got another one. I'll be more careful with this one.

I don't really care about the sensor part. I may deal with that on the broken-red one, but this one is just a light to me. First, I identified the colors that each pin went to. Almost every single one of these lights are common anode, and this one was no different. I soldered color coded wires onto the exposed

Once I tested the connections, I hot glued the connections immediately to secure them in place because there wasn't a whole lot of solder on the connection. I didn't want a random broken connection, so I decided to play it safe.

Next, we want to be able to control it with an Arduino, so we need to know what resistors to use. Red, obvious from past experience, needs less voltage than the other colors, so it'll need a different resistor. Also, because this is a common anode LED, we need to treat it special as well. Here's how they're the brightest and the common resistors needed to bring it down from the 5V Arduino power (and the approximations with the resistors I have on hand):

• Red: ~75mA @ 2V - 82 Ohm (47 Ohm + 47 Ohm)
• Green: ~10mA @ 3.5V - 150 Ohm (100 Ohm + 47 Ohm)
• Blue: ~30mA @ 3.25V - 68 Ohm (47 Ohm + 22 Ohm)

Now we can light it up with our Arduino. Now it's going to go into our Game Console project for what will hopefully be a cool effect. Stay tuned for that exciting reveal!