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Estel's Avatar
Posts: 5,029 | Thanked: 8,582 times | Joined on Mar 2011
I finally finished modding mugen cover to contain camera lens cover Here's tutorial:

1. Disassembling mugen cover is easy as a piece of cake. Just use case-clip opener (as in my picture) or screwdriver/whatever flat and hard, apply some force and *click* it's disassembled:

Here we see both parts + switch used by vanilla mugen cover to enable open camera mode. We won't use that switch, so we can save it for other projects.

2. Now we need to make room for our cover. Easiest way to do it is using sandpaper. Try to cut/sandpaper part covering camera evenly, of course only so much as for thickness of Your cover (camera one) material. I decided to use old, deactivated credit card - is both thin and hard enough, being little elastic at the same time, which is crucial. We also need to cut off two mugen cover "legs" - without that, our camera lens cover won't have place to be opened.

3. That's shape of part i have cut to act as cover lens - keep in mind that this was version 1 that doesn't prove itself on "battlefield" I marked part that i initially cut off, but You need to keep it (my actual version contain that missed part). Without it, You'll face problems closing cover after taking photos - it will get stuck with parts of mugen cover. Anyway, You may wonder why its bigger than cover we need - we will use it also to cover/uncover sensor controlling "camera lens open" event in dbus. That's why mugen switch was obsolete.

Be warned - i used black card, so I got no need to paint it. If Your card/material of choose is different, remember to paint in black part that cover sensor. Black is for "lens closed", white is for "lens opened. N900 sensor... well, sense if something is white even in full darkness (closed cover).

4. Now, it's very important part. due it with care, without haste, if You want really functional lens cover, that won't get stuck. Anyway, we don't want to break and glue mugen cover again in again, don't we?

In picture below, I marked two parts, also cut off from remaining of credit card. "Blocker" act as blocker - it won't allow camera cover to go further, when it reaches "lens closed" position. Blocker on another side isn't needed, cause wall of mugen cover itself act as second blocker.

Part leading way for camera lens is extremely important also. It must be glued very precisely, to not allow our camera cover to shake left or right, in the same time being not too thick placed - our camera lens must go smooth. Side touching with part covering camera open/closed sensor touch part of mugen cover, and that act as second "lead".

I incorporated smart idea here - last part of our hand-made lead is little thicker that it should, but not glued (i marked it with green on first picture, and red in second). If it was glued, it wouldn't allow our camera cover to close, but now, it act as elastic "lock" - you need (very little) force to close camera cover, but then it won't open, no matter how hard you will shake Your N900. Note that "open" position is also stable - mugen cover construction act as second lock, so when it's open it won't close on itself neither, no matter how hard You can shake (N900 or Yourself ).

As for glue, i used 2 part epoxy. I won't recommend cyano-acryline (or whatever they're called in english) - i.e "fast miracle" glues that work after few seconds - it's good for other purposes, but isn't resistant to vibration, and can de-attach after some time.

5. another important thing is to glue something white in part that will face camera lens sensor - below our camera lens cover (looking from inside mugen cover, as on next picture). I used part of white eraser gum, that i shaped using knife and sand paper. It must be attached a way so it works like that:

a) Camera lens opened - sensor is facing our white part.
b) Camera lens closed - our white part is covered by part of credit card (or whatever material You use), so sensor is facing black part.

I also covered remaining from vanilla mugen "camera opened switch" - also used part of credit card here, just glued it on place. Another part of credit card was used for me to make "helper" that allow Opening cover with Your fingertip, when it's attached to N900 and You're on real life situation. Don't forget about making Your own "helper", without that it's impossible to open cover. (You can see how it looks on "finished" photos, at end of this tutorial)

Cover opened, view from inside:

Cover closed, view from inside:

6. Last step is to glue together both parts of mugen cover again, with our camera lens incorporated. Because 2 "legs" that vanilla mugen used to keep parts together were cut off by us, we need to use little more glue on mugen cover "small part" edges. I also recommend epoxy here. Don't get scarred by "glue mess" inside cover - i cleared it with isopropylene alcohol, after glue cured where he was intended to be


And here it is - fully working camera lens cover incorporated into mugen cover Only one thing You need to activate "camera lens opened" event, is to... Open cover, as with stock N900 cover. It works like a charm, open and close smoothly, stay in given position, and doesn't affect photos at all (in fact, i checked if photos would be affected if cover would open even less, and it can be even almost "half-opened" without affecting photos. This is due to optic characteristic. So, that amount of space our cover leave when it's open is absolutely enough, and even more than we need).

I know that it can be made more pretty - using for example aluminum metal part as cover, with shaped part as "helper" to open cover on real-life situations - but, as long as it works flawlessly and doesn't look REALLY bad i can't care less about visuals.

N900 with mugen cover and camera lens opened:

N900 with mugen cover and camera lens closed:

It was very satisfying to do that mod - of course it took much longer than i expected (with few fail-designs of cover shape), but overall experience was great.

I hope You will enjoy it, if You decide to make one.


As an addition, here is picture of another very simple tweak that I've made doing mugen camera lens mod - i recycled magnet from mugen cover and glued it to N900 counterpart itself, so i don't need to switch swap into emmc when taking cover out. When i want to switch swap or unmount/mount microSD vFAT, i got scripts for that (can publish it if anyone's interested). Of course if You use this little modification and swap on microSD, alway re-swap swap into emmc before taking microSD card out of slot, or You'll face instant reboot and possibly severe filesystem corruption (you can as good take RAM out from working computer). It's also not good to take microSD out when doing operations on card - even when tracker does it, so it's always recommended to unmount microSD vFAT before de-attaching card.

Side info:
I've bought mugen cover with doing this modification in mind. Now I'm in process of upgrading it with stable, strong yet thin "leg" for our N900 with mugen cover, to allow placing it on desk on given degree, without fear that we'll break that "leg", or that N900 will fall from desk (as with stock cover "leg"). I'm also investigating ways to make quick, simple and effective dual scud mod that will allow external charging.

In meantime, I'm - for few weeks now - working on real overkill - "real" hotswap of batteries on the field, without any limitation on usage (can be done with wifi on full transfer, 100% CPU, max brightness, 3G data going on etc.), that everyone will be able to do themselves and materials will cost only few bucks.

Initial tests proved every idea true - ho ever, to get sure that no one (me including) will fry they N900 / screw batteries after some time of usage, I'm doing extensive testing and design improvements. Of course, results will be published here, on, no matter what.

I already spent >100$ on equipment just for this project (of course i admit I'll happily use it also after, for other hardware mods) - for semi-pro RC charger, professional multimeter, very thin gas powered soldering iron, and many bigger or smaller li-ions (yea, my hotswap solution is based on incorporating into mugen cover additional, small li-ion energy source, connected to N900 by special switching mechanism).

If you like to support my efforts - that are mostly slowed down due to cash limitations - please donate. Every amount welcomed.

(donation link will take You to another page with working donate button - it's normal, no need to worry)

Please also remember about dr_frost_dk - without his battery tests and mods, none of these would be possible.


Last edited by Estel; 2011-06-29 at 20:07.

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