Probook 450 G2 Disassembly

[Kylee Mccandrew]

Ineed to replace the CMOS battery. Following your guide, I have the laptop totally disassembled but I still cannot access the CMOS battery because it is under a plastic piece and I cannot get to it. Any idea on how to remove it?

my 4540s dosent power on nothing and i already change the ac cable and the batery but still nothing. what u think could it be this harness or the motherboard, can u send me the answer to my email please

@marie: Did you remove the keyboard screw in the middle of the cooling cover first? See photo in Step 4. Then after removing the other two screws in Step 14, the cooling cover should slide to the side very easily.

Thank you for the perfect disassembly instructions and photos. So helpful.

Maybe a note can be added to step 14: If you did not removed keyboard in the previous step, remove also the 3rd screw in the middle of the cover.

My Laptop Screen becomes black some time white cables coming from motherboard to screen on both left and right side . I found some cable from Motherboard to Screen in left side is intermittent. when I move it with some visiting Card it becomes normal I am an electron sub Engineer, retired from Air Force how i can reach to these cables to repair it. If some one can help me I will be thankful to him.

I have a HP ProBook 4540s with a continuously blinking power led, even though the power cord is not attached but with the battery in place, that will not power on. Any suggestions on how to diagnose the cause of the blinking led and/or the unit not powering up would be greatly appreciated.

P.S. Thank you for your instructions along with annotated images on how to open up the laptop. They were very clear and easy to follow.

If your laptop is overheating during operation and sharply turning off, this most likely is overheating of the cooling system. The reason for this is the accumulation of dust on the radiator. If not clean the cooling system in a timely manner, it may cause damage to the laptop. You can eliminate this problem by repeating the procedures shown in the video below.

This information is provided for informational purposes only. We accept no liability for damage caused to your device while following the video instructions. Also note that if your laptop or any other device is still under warranty period, then in the process of dismantling the guarantee may be canceled because traces remain after disassembly and it violates the terms of the warranty period. Before disassembling, make sure that the warranty on your laptop has been over.

The basic structure of Thunderbolt naturally needs to be changed to suit the form of JHL8440, but there are only two Thunderbolt ports in the G4 Dock, and the PD controller shall also be reduced to one. The base structure should consist of CYPD5235, JHL8440 and FL5801, although the possibility of using a Texas Instruments PD controller exists.

However, the mechanism for fixing the wire tail has been changed compared to G2. In G4, it has become a mechanism that can be rotated by two resin hinges. In G2, it is a very direct tooth-like combination.

In the subsequent disassembly process, the steps taken for the G2 are repeated. The top board in the docking station is called the Top board, and the bottom board is called the Bottom Board. First separate the top fan and IO shield. As soon as the fan is removed, you can see a shield and MUX facing the network port.

Detach the Bottom Board. Compared with G2, it is a little simpler, and the three inter-board interfaces are separated. Since the eDP is fixed with tape, it is not separated here. The operation of adding a cooling pad to the sticker here is a bit confusing. The pink thermal pad that was torn and folded has dried. It appears it was like this when it left the factory, not due to disassembly.

Separate the top board, you can see that the DC port is still not soldered on the board, but fixed on the metal heatsink; the DC port extends two cables, and a group of black and red multi-wire interfaces are connected to the bottom board, which should be the main power supply function. Another thin cable connected to the top plate should be the identification mechanism responsible for the power supply; The Power cable is also divided into two connectors in G2, but both are connected to the Bottom Board.

In general, compared to the PCB of the G2 dock, the G4 has little difference in the layout of the main components, but the high-speed signaling is mostly moved to inner layers which makes tracking them difficult. You can clearly see the high-speed differential pair wiring of the JHL8440 to the downstream TB4 port and the associated coupling capacitors and diode protection; the slightly larger TVS above should be used for the USB2.0 interface protection. However, the wiring to the upstream TB4 interface on the other side of the board is basically untraceable.

There are 5 pairs of differential lines coming out of the eDP interface. The top two pairs are directly connected to the i225 network card. The pair on the left is equipped with a coupling capacitor, which seems to be the RX TX line of PCIe X1; the clock line of PCIe is not very clear.

In terms of network card, before the LAN port MUX, it is clear that 4 pairs of differential lines are connected to i225, and the differential pair indicated by the yellow arrow is connected to RTL8153.

The other three differential lines connected to the RTL8153 can also be seen on the back. Downstream of the MUX, you can see the three pairs of differential lines connected to the network port protection IC, but the fourth pair is hard to find.

I have limited materials on hand so unfortunately I will only do the simplest tests. The USB-C port of this portable screen only supports the 4Lane DP1.2 mode and the display supports up to 4K 60Hz. In theory, when the G4 is in Thunderbolt mode, the effect of connecting the screen to the multi-function C port or the downstream TB4 port is the same (both 4K@60Hz). However, in fact 4K 60Hz display can be achieved when connected to the downstream TB4, but only 4K 30Hz can be set under the multi-function USB-C port. Theoretically this problem is caused by VMM5323 compatibility.

Here is the test applied with Samsung S20. After linking the G4 to the phone, the P50 portable SSD and monitor are connected. The monitor can trigger Samsung DEX normally, and the S20 can also read the contents of the portable SSD, but the display is limited to 1080p 60Hz, which should be the limitation of the phone itself.

In general, we use HWinfo to probe the hardware structure of G4, mainly in terms of the USB hubs and the basic design of Thunderbolt dock. HWinfo is still not very reliable for relatively complex structure exploration so a teardown is still needed.

For the device PID=800A at the beginning, HWinfo did not detect the specific device name. According to the tree structure parallel to FL5801, it can only be determined that the device is JHL8440. In USB mode, it only acts as SuperSpeed+ hub. Hub functions of USB2.0 is completely handed over to FL5801.

The USB4206 at the lower position, was not found during the disassembly process. In theory, this is the USB2.0 part of the USB7206 that is connected to the FL5801 and enumerated. In fact, MicroChip does not have a product named USB4206.

The USB tree structure is basically the same as the previous DP Alt Mode, but the RTL8153 originally under the USB5744 is gone; the P50 is still mounted on the downstream TB4 interface, and it is still located at the Port 1 position under PID=800A. Although PID=800A should belong to the 10Gbps USB hub mechanism of JHL8440, more mechanisms of JHL8440 emerged in HWinfo when in Thunderbolt Mode. It is reasonable to think that the hub mechanism for Thunderbolt/USB4 Bus and PCIe are separate from the USB hub mechanism we mainly observe, but the related investigation work will not be carried out here.

In addition, there is an unexpected feature. Whether in Thunderbolt Mode or DP Alt Mode, after connecting the P50 to the front USB-C port adjacent to the host cable (as shown in the figure below), the P50 is determined by HWinfo to be mounted on Port 3 under the device PID=800A.

When the P50 was previously mounted on the only downstream TB4 port of G4, HWinfo showed that its position was Port 1 under PID=800A, so in theory, Port 3 is a peer position, which is the downstream TB4 interface directly provided by JHL8440.

Thanks for you answer. The dock is already updated and I think HP is never going to release an update sadly. Frankly I would like to use these keys without adding any new hardware staff as already have many items on my desk. I wonder if a software could solve this issue.

Hi Dan, I connected G4 dock to HP Probook 435 G8. My network switch is capable of 2.5GBE. However, in network adapter list, it only shows Realtek 1GBE adapter from the dock. How do I change it to use Intel adapter for 2.5GBE? Thank you for your help !!

Thanks for this very insightful layout plan, is my assumption right that it would be possible to connect 22 USB peripherals and 3 TBT4 perif/passthroughs, if all parts would be made accessible, and operative?

And all the clutter of cables can be tucked away nicely under the desk which prevents ports getting dusty and intermittent trouble prone, and preventing accidental unplugging of peripherals by nudging the dock which easily happens with a loose docking staation.

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