Author Topic: Help on how to open electronics device housing  (Read 373 times)

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Offline holger

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Help on how to open electronics device housing
« on: February 14, 2020, 03:21:53 pm »
Hi there,

I bought a “Cleargrass” air quality tester from China:
Great device (while it worked), great build quality. See https://qingping.co/air-monitor/overview (Google translate helps with the Chinese) for more details.


A few weeks ago, it started to make terrible noise, caused by an internal fan (used for the particulate matter sensor).

I've tried many things to open the device but all in vain. Things I've tried:
- use a prying tool to remove the display unit from the main housing
- heat the device up and try above
- remove the back lid and push the inner part to the front

I did manage to remove the back lid (snap-on) and a front blend (glued-on), but I just can't find a way to open it to reach the fan.
Would greatly appreciate any help and any suggestions what you would try.


Bonus-question:
I applied heat to the housing, hoping that glue would get soft for opening. That failed, but the fan didn't make any more noise for a day. This effect is repeatable. Any idea why the fan noise went away temporarily by heat?


 

Offline tunk

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Re: Help on how to open electronics device housing
« Reply #1 on: February 14, 2020, 03:52:00 pm »
Maybe there's screws under the rubber feet?
 

Offline andy3055

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Re: Help on how to open electronics device housing
« Reply #2 on: February 14, 2020, 05:23:40 pm »
In the first picture it shows 4 square holes at the 4 corners. There must be locking tabs inside those. As for the heating, it must be that the fan is touching the housing ever so slightly and the heat must be making it clear just enough to get rid of the touching.

One more thing. If there are labels, there can be screws hidden behind them also.
 

Offline tunk

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Re: Help on how to open electronics device housing
« Reply #3 on: February 14, 2020, 06:25:17 pm »
Looking a bit more at the last picture, it looks like the display unit
is screwed onto the rest and that it slides out backward. Again from the
last picture: To get access to the screws you have pry the display itself
from the display housing. You could try a hack, drill out the sliding locking
tabs from the back and slide it out forwards. YMMV.
« Last Edit: February 14, 2020, 06:31:11 pm by tunk »
 

Offline LateLesley

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Re: Help on how to open electronics device housing
« Reply #4 on: February 14, 2020, 07:12:20 pm »
To me, it looks like the bulk of it is just pushed into the grey "shell". Have you tried pushing the black plastic part into the outer shell, to slide the shell off? It looks as if it just slides in, and the end cover plate you've taken off retains it.
 

Offline holger

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Re: Help on how to open electronics device housing
« Reply #5 on: February 14, 2020, 07:56:48 pm »
Thanks so much for all of your feedback!  :-+


I tried all of your suggestions and it turned out to be the most ludicrous solution:
I had to remove the LCD display from the display bezel/frame - the screws were underneath! Then the whole "cart" can be pulled out easily - in the direction towards the back (that's why pushing from behind didn't do anything).

This must be the most repair-unfriendly device I've seen, even beats my old iPod mini!  :palm:

Of course, I ripped one of the flex circuit cables.  |O Luckily, it's the least important of all, the light sensor for background light adjustment.

I finally arrived at the fan, it's one of these: http://www.d-fans.cn/product/high-speed-dc-blower
I'll see if I can find a replacement, potentially from Alibaba (should they ship a single piece).


A few more questions now:
- any realistic chance to fix a flex circuit cable?
- any suggestion on a specific glue to glue the LCD back onto the bezel?
- if I can't buy the fan (they might not respond for a single piece), any hints on finding a replacement or repairing it?
 

Offline andy3055

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Re: Help on how to open electronics device housing
« Reply #6 on: February 14, 2020, 08:43:16 pm »
Even if they are willing to ship just 1 piece, it may be a while before anything comes out of there. Why not try to fix the problem with the fan? From what you wrote earlier, the blades must be touching the housing somewhere. A careful observation should show you where it is. If the blades are wobbling due to a bad bearing, it is another matter. But I doubt that very much.
 

Offline tunk

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Re: Help on how to open electronics device housing
« Reply #7 on: February 14, 2020, 09:20:59 pm »
If you can get access to the bearing, you could try a small drop of oil.
Also try to remove the metal shield, the fan may work without it.
 

Offline holger

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Re: Help on how to open electronics device housing
« Reply #8 on: February 14, 2020, 10:08:08 pm »
Thanks for the hint. I double-checked, the blades are not touching the housing and rotate very easily.
 


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