How to fix failing hinge on Acer Chromebook 315?

dreadedhill

Have a Chromebook with a failing hinge, and need to figure out what to do.

Bought this Acer Chromebook 315 for my ten year old grandson. He uses it a lot, and of late for Zoom sessions with his school class. During this last week he sent a very worried message, with a picture of a split case for the screen.


Bought Acer as I have generally liked the good build quality of the machines. (For the price point - no question these are inexpensive units.) Three (of five) went to family members, as I was comfortable recommending. When this 15" touchscreen Chromebook arrived, the case did feel a bit flimsy.

Pretty sure this unit is (just?) out of warranty. 


At first, tried gluing the split, using "crazy" glue, clamped together (very careful to distribute the load on the fragile case), and left to cure overnight. Noted that the left hinge seemed excessively stiff, and ... not aligned? This lasted a few days, then split again. Noticed the left hinge was worse - no way the fragile case could take that load.

Now trying to figure out if this is repairable, or if I need to buy a new unit.

Did find this thread:
https://community.acer.com/en/discussion/547171/acer-laptop-hinge-issue
And saw the response from "Acer-Manny" https://community.acer.com/en/profile/Acer-Manny 

While it is great to hear that Acer does some(?) testing in-house, the fact is real-world use is different. If units are failing in the field, you want to pull back (at least some) failing units, typify the failures, and update design. Yes, I understand this is a cheap build, to fit the market. Yes, I understand that "thin" is fashionable. But ... this is a frigging hinge - not exactly cutting-edge tech. You overshot and built something too fragile.

Yes, I can replace this unit without any personal financial bother. But one of the comments on the above thread was from a kid who for whom this inexpensive Chromebook was a major investment, and the loss devastating. Long ago, I was that kid.

Yes, I know that economically you cannot take back every failing unit. But you can offer that kid the best path forward. Be helpful, even when you make mistakes.

Now ... I have a bunch of browser tabs to read through, to see if a repair is reasonable. And yes, if I buy a replacement, will be a bit more wary about Acer.

Edited the content to hide sensitive information.

dreadedhill

Well, found your problem. A series of mistakes... yes, mistakes by Acer.

First, on disassembling the unit, found all the screws in the bottom were lose. (One had fallen out.) The threaded inserts in the plastic were a nice touch, but not enough. (Not properly tightened screws, and/or no use of Locktite or the like. Guessing the soft plastic helped the screws loosen.) Not the root cause, but a warning sign.

Second, saw the (very slender) metal left frame was broken. Clearly more stress than it could handle. Still not the root cause, but getting closer. Also the screws attaching the hinges to the frame were also loose. Assuming this was not careless assembly, then - again - soft plastic flexing helped the screws loosen. Also, the plastic bosses were broken. Given the concentration of stresses, even with the threaded metal insets, the plastic could not take the load.

Last, the left hinge was tight as f**k. Seems the adjusting nut tightened in-use, as there was nothing to keep the nut from moving. Backed off the nut, and the hinge moves normally. (Locktite or equivalent would have been good.)

So your root cause was the hinge adjusting nut that tightened during use. You cannot ascribe this to "abnormal use by customer".

The tightening hinge caused a cascade of failures.

(Now trying to figure out if enough hot-glue and/or epoxy will be sufficient.)

billsey

Looks like you are doing some good diagnostics there. Did you buy the unit used or refurbished? I ask because Acer does usually use Loctite Blue, or a clone, on the case screws and on the hinge screws. I haven't taken very many hinges apart so can't opine on thread sealer there. The assembly process shouldn't be impacted much by having it on the threads, so I don't think leaving it off would be a cost savings, though costs are the driving factor on the lower end Chromebooks. Which model is it and when was it built? Should be something like CB315-xx-xxxx...

dreadedhill

billsey said:

Looks like you are doing some good diagnostics there. Did you buy the unit used or refurbished? I ask because Acer does usually use Loctite Blue, or a clone, on the case screws and on the hinge screws. I haven't taken very many hinges apart so can't opine on thread sealer there. The assembly process shouldn't be impacted much by having it on the threads, so I don't think leaving it off would be a cost savings, though costs are the driving factor on the lower end Chromebooks. Which model is it and when was it built? Should be something like CB315-xx-xxxx...

Pretty sure I bought the unit new, but not recalling where bought.
(Not on my Amazon account, apparently. Maybe from Acer direct?)

I did find a blue substance on some screws, but not the loose screws. Maybe the assembler cut corners?

A picture of the tag, with model# and assembly date is in the first message.

billsey

Ah, CB315-2HT then. The part numbers for the hinges are:

• HINGE L 33.H0KN7.001
• HINGE R 33.H0KN7.002

dreadedhill

billsey said:

Ah, CB315-2HT then. The part numbers for the hinges are:

• HINGE L 33.H0KN7.001
• HINGE R 33.H0KN7.002

Thanks. Strictly speaking the hinge itself is fine. The slender metal frame attached to the left hinge is broken. Plastic bosses in the base and screen plastic frames are destroyed on left and partly on right. Lots of epoxy (or the like) at minimum. Bit dubious about the repair.

I just do not have time to work on this, at present. (Trying to PXE a herd of stateless / no storage boards in a very expensive gadget, at present - in a few days not weeks.) Going to give my grandson another Chromebook, for now. Maybe buy a replacement (and less sure about Acer).

dreadedhill

So ... lots of glue. Most of the plastic bosses attaching the screen to the body are broken. Doing this in stages. Using "Gorilla Glue" (acrylic?) and clamps to attach bits. (Later disassembly is unlikely.) Another 24 hours, and might attach decorative bits. Might even still work as a Chromebook.

Hinges now have Locktite (blue) on the adjusting nuts. (The root cause of failure prior.)

On review, most (not all) of the once-loose screws have something blue on the threads. As they were loose to falling out, guessing whatever that blue stuff is, it is not effective as thread-lock.
  

dreadedhill

Just to finish this off, my grandson has had his Chromebook back for a few weeks, and is very happy. Several rounds of glue/clamp/cure did the trick. Did not use any new parts. Critical screws have proper/actual Locktite. The glued bits are holding, and likely stronger than the original. The hinge adjusting nuts are properly adjusted, and should hold their settings.

But the original fault for the failure lies with Acer.

billsey

Good to hear you got it sorted. If your experience is transferable to other similar systems it sounds like the hinges work like the hinges on my glasses. One side loosens each time you open them, the other side tightens. That's kind of inherent whenever you have both screws turning the same way to tighten/loosen. The fix they should look at for future models is either a riveted pivot, reverse threads on one side, or better thread adhesive, as you did.