What's inside a laptop port replicator?

Overview

Ever wondered what’s actually inside a laptop port replicator or docking station? In this detailed teardown, I open up an HP port replicator to explore its internal components, PCB design, and mechanical systems. Perfect for tech enthusiasts curious about how these devices work and whether they contain active circuitry or are just glorified pass-through connectors.

Key Moments

• Overview of the HP port replicator’s extensive port selection (VGA, DVI-D, S-Video, composite, PS/2, serial, parallel, ethernet, USB)
• Removing screws and opening the case to reveal internal mechanisms
• Discovering the surprisingly complex mechanical eject system with springs and levers
• Examining the PCB and identifying chips (UART, power regulation, unknown ICs)
• Analyzing the main connector with power distribution and data pins
• Conclusion: Most signals pass through directly from the laptop

Full Transcript (Edited)

So I’ve had this HP port replicator laying around here for some time. I had several of these with the laptop that came with it, and I went ahead and got rid of the laptops. I sold them, and some of them I included this replicator with. This is the last item from that batch of computers that I have left, and I thought it would be kind of cool to see what’s inside of it and do a little teardown, since it’s not really worth much money. Without the laptop, it’s pretty much useless, so I thought in the name of science I would tear it apart and see what’s inside.

I’m expecting that there’s not going to be much in there except maybe a PCB that splits out all the signals in this connector to the back. But this is a very full-featured replicator. I’ll show you in a bit what I mean, but I thought it would be cool to tear it down to see if there’s actually any circuitry in there.

Let me start here. This is a push button power, so you can actually turn the power on and off for the laptop. Let me step back a little bit. If you don’t know what a port replicator is, a lot of business laptops have these ports on the bottom of the laptop, and in some cases in the back. What you do is, let’s say you have a station at work and a station at home—you could have a replicator like this sitting on your desk, and then you can connect all your peripherals like your larger LCD monitors, your network connection, USB mouse and keyboard or PS/2 mouse and keyboard, your loudspeakers, and even TV out on your desk. So when you get home from work, for example, you can just plop your laptop on here and then use the bigger screen and the full-size keyboard. Your laptop becomes a desktop PC at that point.

So that’s what replicators are used for, and they’re really good for business computers because you can transform your business computer into a desktop at work and a desktop at home. That’s kind of cool.

On the left here, we have a lock so you can actually lock this down to your desk. Then you have S-video output, you have composite video output. These are interesting to have in a replicator. This looks like some kind of additional VGA output, even though there’s one here. This also looks like it has some kind of screen output. Maybe this is some kind of proprietary plug that HP shipped with this. Then you have line in, line out or speaker out, you have PS/2 keyboard and mouse, so you can plug that in. This is for an older laptop, so it makes sense to have these PS/2 keyboard and mouse. I think this is an early 2000s laptop, I believe.

Then we have a serial port, a parallel port, a VGA port, and a DVI-D port. So technically you could probably break this out to HDMI using one of these adapters. Then you have power, so you could actually have this charge your laptop. You have a modem, you have ethernet, and two USB. You also have two USB on the side over here, underneath the power button.

On the other side, you have what looks to be like some kind of lock cover—I don’t know what’s under there—and then you have this eject button. You can see here, this eject button probably has some kind of angled thing underneath there, because this is thin over here and then thicker over here. When you press this, it pushes and unlocks the laptop.

This connector down here has a lot of stuff going on. There are these—this is probably power either going from here to the laptop, or maybe on this side they have power distribution split out, and then maybe the laptop power goes back into here, because if you don’t have the AC adapter plugged in, you need to power up this thing with power from the laptop. So I’m assuming this is going into the laptop and this is coming from the laptop into this device.

Then you have all of these data lines, all of these ports and everything. So it’s quite possible that this is just a pass-through and there’s no circuitry in here to support any of these ports, and that all the circuitry to support all those ports is inside of the laptop and then they just get exposed through this connector here.

All right, so let me zoom out again. So like I said, what I want to do is I’m curious—I want to open this up and see what’s inside. It looks like it’s going to be fairly simple. I’m going to start by taking off these three screws right here.

[After disassembly]

All right, so I went ahead and removed all the screws. As you can see here, this little piece came off—it’s a little protective foot. I’m not sure what this is supposed to—oh, it’s another type of lock! That’s what that is. It’s a little cover that comes off and then you can put a maybe a more secure locking mechanism in there.

Okay, well let’s see if I can take this apart. I’m going to try to lift off the top. Okay, so it just lifts off. It does look like it has some electronics. Let me unplug this cable down here. Okay, that’s unplugged, and then this comes off over here.

All right, that came off. Now we have the two parts. Let’s start with the top. This is the mechanism. It looks like it’s kind of self-contained there. So let’s see what’s going on there. I pushed on it—that’s actually a lot more than I expected there to be down here, to be honest. I didn’t expect all this metal and magnesium. Look at how many different parts there are here, a bunch of little—that’s a lot. This is like—it’s not a simple mechanism. I thought this was going to be a lot simpler, but there’s a lot of stuff going on here.

So I press this, look at that—there’s a spring there, there’s little grease there, there are more springs down here, more springs on there. Then you have all these screw holders and the standoffs. Then you have the power button which has four wires—oh, because two are for an LED, there’s an LED here. Okay, so two are for an LED indicator and the other ones are for the actual power button. That makes sense.

Then you have these standoffs. There’s another little PCB here. What is that for? Oh, it’s another LED, but where’s the cable, where’s the power for that? Oh, that’s the little cable that I unplugged there for the LED indicator.

Well, this is a lot more than I expected for this mechanism, but I like that it’s self-contained and that it doesn’t come apart when you disconnect both halves. That’s cool.

Let me put this aside. Now let’s take a look at the board. So we have this PCB, and then we have this—what is this? We have this tape. Let me take this tape off so we have better visibility here. Not sure what this does other than maybe protect the circuitry there.

All right, so let’s take a closer look here. So we have on this side over here—what do we have? We have this chip here. This chip, what does this chip do? It’s a CY7C65—I’ll look it up and see what it does. It’s probably something to do with the network or the USB ports here. Let me see where the wires go to. Yeah, I’m not sure. I’ll look it up and put it on the screen if I find it.

Then we have some voltage power regulation. Then we have this other chip there. I’ll look it up to see what it does and put it on the screen. Looks like it’s probably a lot of power regulation stuff. Then you have this MAX3243, so MAX tends to do like serial ports and things like that, so that’s probably a UART of sorts.

For the most part, it looks like this connector does go straight to the back, and most of the circuitry is on this little board—sorry, it’s inside the laptop, and this is just a pass-through, which makes sense. Why would you—the laptop should have the chipset set up to run all of these ports.

All right, so let me zoom out again and take a look at the PCB. I’m going to take apart the PCB here and see. It’s just a couple of screws here. Actually, I don’t need to take it apart. If I look down here, there’s absolutely nothing. So most everything is on the top. The bottom of the PCB has nothing. So that’s it. This is all that there is to it.

It looks like all of it, if not most of it—sorry, most of it, if not all of the signals—end up coming from the laptop. Other than this UART and this other chip over here, there’s nothing else in here except some power regulation circuitry, and that’s about it.

Yeah, so interesting. This is the video cable of sorts here. What does it say? Does it say on the PCB something? Let me see. No, it just calls it C—it’s just a connector on the board. Yep, I don’t know. It looks like even all these video outputs come from the video card on the motherboard of the laptop.

So interesting. That’s nice. The laptop was very, very full-featured. Yeah, I hope you found this interesting. I don’t know, it’s one of those things that I was just curious to see what was inside. I mean, I’ve dealt with a lot of these port replicators before, and part of me always thought it’s just like a pass-through like this. But this one just caught my attention because it had so many ports that I figured maybe there is some circuitry on this thing that actually handles—that maybe this is like a PCI bus and then the circuitry for these things like the chipset to handle the parallel port, the DVI video, all this stuff would actually be handled by circuitry on here.

But nope, it looks like the laptop does everything, and this is just what it is—a port replicator. Ports are coming here and then they get broken out into what they are.

So yeah, let me know in the comments what you think, and if you found this interesting. Hopefully, that way you don’t have to tear apart yours. All right, I’ll see you next time. Bye-bye!