Did I kill this laptop?
April 3, 2021 5:17 PM   Subscribe

I have an asus ux501vx. I replaced a defunct fan, now it has no signs of life.

Briefly, I took the bottom case off and verified that it was one of the two fans making all the racket with the machine running. I then powered it down, unplugged, and disconnected the battery. Removing the fan was a little tricky (if you aren't familiar with this particular machine, there's a little bracket keeping the fan in place under the heatsink connection) and the screws were it very tight, so I had to lift up the big copper piece a bit. As you can see in that image, the CMOS battery is taped to the right fan, and I unplugged it to take the fan out. I left it like that for several days while waiting on the replacement part.

When I plugged everything back in:
- the main lightbulb light turns on (either on battery or with battery disconnected and wall power connected)
- the battery light will come up with battery and wall power connected
- holding the power button for 20s will force some kind of shutdown (the main light turns off, then turns back on a few second aftet I let go)

Other than that, no signs of life. No post image, the fans don't spin, no sources of noise. I didn't check the temp but didn't notice it getting hot. I tried discharging any static by holding the power button with everything disconnected and the hard reset options. Following that link, I also put the bios image on a flash drive with the control-r bios recovery key and tried the various screen output manipulation options.

It's possible that I just destroyed the chip while manipulating the heat sink or damaged some other component on the motherboard (though I don't think that I did). I also expected the bios to be reset because of unplugging the cmos battery, but I've never heard of that bricking it. I can't actually check the cmos battery (it isn't a coin, it's wrapped and has an extremely tiny female connector) but it was working before and I doubt that it would have stopped (I guess without actually discharging the main battery you might not notice if it was dead?).

Other than ordering a replacement CMOS battery and praying what are some next steps that I could think about? How could I get closure that I did wreck the chip if that was it? I don't have the chip flashing setup, but I guess I could do that if it is even possible with this board. When I was younger I really crushed one edge of a desktop chip while installing a heat sink, and it would at least post. As much as I liked it, the thing is 5 years old now and so this is more of a hobby-repair than something I want to put a lot of money into.
posted by a robot made out of meat to Computers & Internet (8 answers total)
 
I'd try at least reseating any connectors/components that might have been jostled, in particular your memory module, and if you have or can borrow a multimeter check the voltage on that battery. If you're that close to giving up on it, wiggling stuff a bit can't really hurt.
posted by phooky at 6:09 PM on April 3 [1 favorite]


Even if the CMOS battery was removed, you should still boot, but with default BIOS settings. Check to make sure that all the flex connectors are fully seated.

Can you try powering up with the charger connected? If you have one of the IR thermometers, you could check the temperatures a bit more precisely to make sure nothing is getting unusually hot (I would say over 70 degrees C would be hot).

Also try powering up without the new fan connected; perhaps there is some problem with the replacement fan where it is shorting out the power supply.
posted by coberh at 6:14 PM on April 3 [1 favorite]


Chances are you unplugged one of the ribbon connectors when you "pulled" on something. I'd do a full disassembly (as much as you're comfortable with) with any ifixit or such instructions, and locate something that should be connected or may be loose, but isn't.

(I spent a week taking apart laptops and reassembling them and learned that those ribbon cables that goes into a connector are the easiest to accidentally "pull out".)
posted by kschang at 8:30 PM on April 3 [1 favorite]


Also, it's not at all obvious but every ribbon/film connector will have some kind of latch mechanism. Sometimes these are a tiny little part that pulls out in the same direction as the film, sometimes they're a tiny little hinged flap that flips up.

It's always possible to yoink the ribbon out (or partway out) of those connectors without operating the latch, but they never go back in the same way; you absolutely need to figure out the latch to re-seat them properly.

I haven't been inside the particular Asus model you have, but quite a lot of laptops seem to be designed in a way that makes it virtually certain that any attempt to take them apart will unintentionally yoink out at least one of those connectors.

I also put the bios image on a flash drive with the control-r bios recovery key

If you've managed to make the machine do something as complicated as creating a file on a flash drive by pressing a key on the keyboard, then the keyboard and CPU and memory are all working. Which means that if you're not seeing anything on the screen, the most likely cause is that the ribbon cable for the display has been yoinked out of its connector.
posted by flabdablet at 11:40 PM on April 3 [1 favorite]


Flabdablet, I used another pc to write the flash drive.
posted by a robot made out of meat at 6:03 AM on April 4


This model comes apart pretty easy. Unlike many models, I was able to get to what I need without disconnecting from the keyboard / top; the bottom case comes right off. I am fairly certain that the only ribbons disconnected were the fan power, battery, and cmos battery. The main battery I am certain is latched (and shouldn’t matter). The fan ought not give me no signs of life and is symmetrical to the other fan. The cmos I tried again at - it really looks like it just slides in.
posted by a robot made out of meat at 6:33 AM on April 4


After going over it carefully to make sure no cables were accidentally dislodged, I'd take a look at the CPU.

When you had to lift up the big copper piece, I assume you mean the heat pipe that runs between the two fans? That's generally thermally and mechanically connected to the heatsink that sits on the CPU. If the screws for the CPU bracket are spring loaded, or even if there's some flex in the bracket, it's possible that the CPU may have been partially unseated while you lifted up the heat pipe. My next step would be to remove and re-seat the CPU, making sure I had thermal paste on-hand, so I could clean and reapply between the CPU and that heatsink. Remove the heat pipe assembly entirely (this may mean both fans), remove the bracket holding in the CPU, and then remove the chip itself. Clean the thermal surface where it meets the heatsink/heat pipe assembly, inspect for damage or bent pins. Reinstall, reapply thermal paste, reinstall the heat pipe assembly. Your heat pipe also covers the board's chipset, where that large copper shield is toward the left fan, so you may be in for some more reapplication of thermal paste.

While you're at it, I'd remove and reinstall the memory, just in case it got bumped and one side became partially unseated.

Is it a true OEM replacement fan or just something with the same dimensions? Most computer fans have not just the ground and +12V for power, but a pin for rotation/speed sensor, and on newer machines, another pin for PWM signal to control fan speed. If it's not a true OEM part, the wiring may be not as expected, and if the motherboard is sensing no rotation on a fan, it may refuse to boot for thermal safety (or, if the wiring is really not as expected, it could be causing some sort of glitch.) If you disconnect your replacement fan, does it behave the same or get any farther in the boot sequence?
posted by xedrik at 7:57 AM on April 4 [1 favorite]


Thanks all. It is a true replacement part, and unplugging it didn't make anything work. The IR thermometer does show some small amount of activity (+6F over chip vs background).

Reseating the memory didn't help.

I removed the heat pipe again, and I don't think that I can reseat the CPU - there is no obvious way to get it out the bracket and no online tutorials seem to cover this. I think it's integrated to the mainboard. You might be on the right track of having mechanically disrupted the CPU while lifting up the heatpipe edge. I will try dropping it off with a local shop before declaring it dead. A replacement mainboard is a couple hundred bucks for a 5 year old laptop - as much as I love the screen!
posted by a robot made out of meat at 7:39 AM on April 5


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