HP Compaq 6720s disassembly, cleaning or replacing fan

The best way to repair or replace parts of laptops, is to read the service manual. But if you prefer a more visual way, please read on.

Or just read the official HP Compaq 6720s Maintenance and Service Guide here.

The HP 6720s is quite aged by now (2022), as it was made in 2008. But it is still well usable with lightweight linux distros, that are listed in this article for example: 15 Linux Distributions You Can Rely on for Your Ancient 32-bit Computer Yes, you can still use the latest Firefox on a 32 bits laptop. (This HP Compaq has a Core2Duo, which can run 64 bits system too, if you really want to.)

Preparing

You need a lot of little small boxes for the screws. I use match boxes. Label them on the go, and I recommend to separate screws from every photo below. (I rarely mixed different screws on one photo, however there are some exceptions to this.) The order of individual screws is not important on most photos.

1. Remove the battery and the RAM, HDD, Wifi card covers

These screws do not come out, do not screw them out fully.

2. Remove the HDD

By unscrewing that screw (not fully) and pulling it softly to the left.

3. Remove the CD/DVD

Remove screw, and then push that little light metal part with a screwdriver, that pushes out the device enough for it to be taken off.

Take out the DVD drive:

4. Remove bottom screws

These marked screws hold the inner cover. (This step is not necessary for removing: keyboard or power switch only!)

More bottom screws, these also hold the inner cover I think.

More bottom screws. These hold the power switch panel/cover. Necessary to remove for replacing the keyboard too!

More "bottom screws", visible where the DVD was.

More bottom screws, these hold the keyboard. Necessary for replacing the keyboard.

5. Remove the power switch panel/cover

Now, that's tricky. You need a flat tool to peal this up, start from the rightmost side, and slowly click-off every little arm that holds it. Make sure to not raise high, there is a cable! Keep it nearly in place when done.

This is the tool I made, by taking off its edges:

6. Remove the keyboard

Keyboard is glued there with two sided glue tapes. Peal it up from top right corner slowly, at top, heading towards left. Mind the cable!!

Disconnect keyboard cable. To do that, you must push the black half "out" from the white half. Push at the two sides with your nails.

Note that when assembling this part, the keyboard cable must be above the moving black part.

(Honestly, I needed to gray out this and next photo at the connector, because it was connected wrong! I made these photos while assembling - and it didn't work! :-) )

Same with power switch cable, push out the moving part of the connector and pull out the cable. When assembling, put the cable above the moving part.

(Some of the similar connectors have the cable under the moving part!)

7. Remove inner screws

(The screw marked with 3 was not in all my HP 6720s laptops. And the screw on this photo is a replacement, please ignore this detail.)

8. Disconnect wifi card

You need to pull out those two connectors. Hold them with your nail and pull upwards.

When assembling, you need to locate their right position exactly and push firmly. This is a very well working connector, but need to get used to it.

Some 6720s disassembly guides remove the Wifi card - I don't find that necessary. (By those two screws.)

Now you can take out the wifi cable on the top side, and pull out from the hole. Put the cable aside, this will came out with when removing the LCD display.

9. Remove the lid close switch

Pull upwards the right side of the little circuit (1), it comes out easily. And then disconnect the cable. Put that little cable aside.

10. Disconnect the LCD display cable

Pull them out from the connector and take out from the hooks.

11. Remove the LCD display

This is secured by 4 screws. Hold the screen while removing these screws!

When assembling, do not forget the grounding cable on screw marked with 3.

After removing these screws, you should be able to take out the LCD and put aside. Sometimes it comes out only after applying a little force: move it lightly like if you wanted to close or open.

12. Remove final bottom screws

You could have removed them when disconnecting the Wifi. They hold the motherboard!

13. Disconnect the speaker

Disconnect it and remove that one screw (do).

14. Remove inner cover

Tricky, but doable. Same technique as with the power switch. I usually start from the rightmost side, with that "knife" tool.

When that cover is free, disconnect the touchpad.

15. Remove the touchpad

This is rarely necessary. Remove it if you need to clean the "mouse" buttons.

Now.. this photo is completely wrong. Those tapes must be conductors! Keep the original glue tapes or find replacement.

Remove the screws and then push the metal part "upwards", so that it comes out from all the hooks. Then the circuits and metal part comes out together.

Clean those pins and the small conductive gum on the small pieces.

16. Remove the motherboard

Peal off that little tape, at least from the fan.

Remove screws at CD/DVD drive, and one more:

Remove screws at Express Card ("PCMCIA").

Disconnect Bluetooth, fan, and take out the Modem connector with a screwdriver as pictured.

Very tricky part again!

To take out the motherboard, start raising at 1, and then push VGA connector in, resulting in pulling the case outwards at same place (at VGA connector). And continue at USB connectors, then you can raise it up enough so that you can pull out the motherboard from the holes of the headphone and mic jack connectors!

Mind that the cooling (heatsink) at the fan will come off, but the fan will not!

When assembling, do this eactly the in the opposite order. I.e. holding in a some degree, push in the headphone jack, push at the USB, VGA, and lower the topmost part last.

17. Replace BIOS CMOS battery (clock)

Verify it or replace to a new as necessary. In my laptops this was a simple CR 2032 battery.

18. Remove heatsink from CPU

Now... according to the attached HP 6720s Service and Maintenance Guide, this part has numbers in which the screws must be loosened. I didn't notice. Follow the numbers on the heatsink, not my numbers.

But just take care in general, you are working with your CPU.

The VGA has a rubber like heat conductor, while the CPU has the usual gel. Usually you won't have the rubber thing, so keep that intact, and clean off and reapply new CPU gel only. I noticed the VGA IC may have this rubber thing to avoid flooding the gel to the small components around it. Or ask a professional.

18. Remove or replace the fan

Two different screws are there, the silver colored is 1, the black is 2. Seriously clean the fan blades and the heatpipe's holes. CPUs like the Core2Duo really need cooling.

I didn't cover disassembling the LCD part. You can find that in the attached guide, but the basic idea is that there are 8 screws under the 8 rubber screw covers. Take extra care, there is mercury in the display.

Using old laptops in 2022 and 2023?

Yes, they work cool and they run the latest software with all fresh updates, if you choose a good Linux distro that is targeted at old or 32 bits computers. Please see the link at beginning of this article.

Links

• HP 6720s Service and Maintenance Guide
• Video: HP Compaq 6720s disassembly and cleaning fan (I used that video to learn about this)