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SGS2 (EU Model) Power button replacement

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EthemD
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Default SGS2 (EU Model) Power button replacement

Hello everyone

The power button of my European Samsung Galaxy S2 broke off when taking out my motherboard. I ordered and received a new power button and am willing to solder it back on, just as they did in this video: ** or in this video for the US version: ** (the motherboards look different for both though, I've got a European one)

Now, the problem is this: there are three connection I need to solder on and despite them being tiny, I'm actually managing well, however only for the middle connection! For some reason, the solder does not stick to the other terminals after trying several times for hours.. the two outer terminals also have a brownish color, unlike the white/silver color of the middle terminal, perhaps that's the reason the solder does not stick? is there rust?? I really have no idea what to do... I am pretty sure there are supposed to be three connection, but really I can only solder the middle one.

Any help/advice would be greatly appreciated!

EDIT: removed the links, but they're the first and fourth videos when searching "samsung galaxy s2 power button replacement" on youtube.
 
keithross39
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Too much heat applied to the circuit board for too long will.....
A) burn the solder points away
B) cause heat damage to other components
My advice would be......
A) make sure the solder you are using has a flux core (the flux will help to 'clean' the solder points during soldering)
B) VERY VERY GENTLY use a jewellers screwdriver or other pointed tool to attempt to remove the brown discoloration on the solder point.....too much pressure will remove the solder point entirely.....so be careful......

This might be my S2, or it might be my W...but it's definitely CM
 
EthemD
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Quote:
Originally Posted by keithross39 View Post
Too much heat applied to the circuit board for too long will.....
A) burn the solder points away
B) cause heat damage to other components
My advice would be......
A) make sure the solder you are using has a flux core (the flux will help to 'clean' the solder points during soldering)
B) VERY VERY GENTLY use a jewellers screwdriver or other pointed tool to attempt to remove the brown discoloration on the solder point.....too much pressure will remove the solder point entirely.....so be careful......

This might be my S2, or it might be my W...but it's definitely CM
I use flux core solder, but i have also used additional flux on the terminals, none of it works :/
I've tried scratching off the brown layer with a toothpick, in case it was rust, but it didn't get off.
I still haven't identified why the outer terminals are brown, is it the EU model or is there really some layer of rust?
 
totalnoob34
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(Last edited by totalnoob34; 5th December 2013 at 12:55 PM.)
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Quote:
Originally Posted by EthemD View Post
I use flux core solder, but i have also used additional flux on the terminals, none of it works :/
I've tried scratching off the brown layer with a toothpick, in case it was rust, but it didn't get off.
I still haven't identified why the outer terminals are brown, is it the EU model or is there really some layer of rust?
Dunno, if you think you have applied flux correctly then try to clean the three points with a toothbrush and alcohol, and a bit of demineralized water. If that works, try soldering again. Otherwise, check you're soldering the right points

EDIT: What's more, there shouldn't be any oxide /rust, since I assume you desoldered/soldered all the points at the same time. Double check you're soldering the right spot, bro

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EthemD
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Thank you for the replies!

I have been stuck with this problem for quite some time now, my first replacement button got broken so I ordered a new one and I've been trying to solder it again and again and it still does not work.....

Then today I did something that revealed the underlying problem!

I decided to have a look at my old broken power button. The three power button contact tips still had some solder on their tips.... HOWEVER the left and right contacts (whose corresponding joints on the board were not working as described) appeared to have flat ends... which I found weird.... so I went with my soldering iron on them and tadaaa... the solder melted and two metal stripes appeared on my table, their back having the exact same rusty color as the two dis-functional contacts on the board! These metal stripes are supposed to be on the logic board in place of the contacts, but as the old power button had been removed by force, they ripped or pulled these two stripes off the board.

See the two photos of them (on the first one you see the back of these, and on the second one i turned them over and put them in their correct position at the joints)

As you can see they are tiny and really difficult to handle. I had difficulties placing them on the board with tweezers, they are very light and got sort of stuck to the tips of the tweezers. Now, I don't know how these circuit boards are built... were these stripes part of a thin layer, from which they got teared off, or were they just glued on the layer below? What lies below a layer of metal contact on a logic board? Any help is appreciated a lot :/
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keithross39
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(Last edited by keithross39; 3rd March 2014 at 11:22 AM.)
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Ok....looking at the pictures, and reading your description of what happened, it looks like the solder points have become detached from the board. This is going to be really difficult to repair.
You have to find some way to trace the circuit path from the button contacts to the next available inline solder point, and then find a way to bridge the break. You can attempt this in one of two ways.
1) solder a VERY fine wire to one of the contacts on the button, then solder the other end to the next solder point along the circuit path....then repeat for the other contact.
2) some years ago, I owned a bottle of electrically conductive paint (called liquid solder I think)
You paint it onto the board over the brown areas that are present, then while it is still wet, replace the button and extend the paint track so that it reaches the button contacts.
In theory this should bridge the gap from where the (now missing) solder point met the circuit board to the button contacts......
Option 2 would be the easier option, but unless you can secure the button so that the contacts don't move, it'll turn into a temporary fix as any movement is likely to cause the paint to crack and lose it's conductivity........
Check this link for solder paint...
http://mobile.maplin.co.uk/module.aspx?moduleno=36275

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EthemD
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Thank you Keith Ross, for the effort to help me,

I have watched a video on youtube, showing how PCB's ar manufactured ("How It's Made: Circuit Boards"), in order to come up with more ideas.

After watching that, I decided to scratch a bit more around and on the faulty terminals, in hope that there will be a conducting layer... however using my DMM I could not detect any continuity on or along the edges of these terminals. Besides that, I have tried again and again to get the solder to stick to those surfaces... but it still didn't work.

Using any adhesive or connecting to a different terminal on the logic board is a bit of a big step at the moment, so I decided to give it to a technician (not from samsung) to look at it. Hopefully he will find a way to mend it back. :/

Really disappointed and surprised that this could happen so easily on the logic board of a SGS2. I'm guessing it's the bad material quality samsung has. :/

While my phone is away, I'll be looking at how to turn on recover mode on my phone without a power button, I already read about how to turn it on without a power button...
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keithross39
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How did it go? Did you get a repair?
About finding alternatives to a physical power button........it *can* be done, but I'd ALWAYS advise having a functioning button as backup. You can download this.... https://play.google.com/store/apps/d...ions.quickboot
and use it to reboot into (amongst other things) recovery, but then you will have to find a compatible 'touch' CWM.......
And to be honest......that reboot app is only going to be of any use if you can access it from a normally booting phone......if you're stuck in bootloop, you're stuffed......
At the end of the day, the only REAL option is to get that button fixed.......

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