Lumia 800 - "Destroyed" a component due to soldering mistake

[lordmaxey]

Hi there,

as i wrote in the Rainbow Mod for Lumia 800 thread, i'll try to restore DLOAD, update to latest FW, and restore Qualcomm (all with ATF Testpoint) again, that i can give you updated files on Partition 3 of the phone, that the latest rainbow mod build will be working on all phones...

But it seemed that i had a pretty shaky hand, when i was soldering my device, that i "destroyed" a component.
First, it was still fitting, but a little "twistet" as you can see on the pictures attached.

I checked if the phone is still working, and it did, except the "light sensor" which turns off the display when making a call... I can now cancel the call with my ear accidently

I realised an extreme heat and battery consumption when making a call... but maybe it just seems so, because i'm looking for "mistakes" because of the broken component...

Then, because of this, i disassembled my phone again, to check the component... and i just touched it a little bit, and now it fell off...

The component i'm talking about is called "L1605" in the schematics plan, so it should be a "coil" (hope this is correct, as English isn't my native lang...)

Of course, because it "fell off", i don't know how it was placed before. Does a coil have a "polarity", i mean "+" or "-" ? or can i just solder it back onto the mainboard?

i hope you can help me

cheers

 

[lordmaxey]

hi there,

i searched again and found out, that the "L1605" is an "27nH_0402". In the schematics plan it's part of the "reciever", as you can see in the image attached.
Can you tell me if this coil is important? It "just" goes to GND, so maybe it would be enough to just connect the to pins (were the coil was placed) with some solder ?

It also seems to be part of "FM & GND", so maybe it's just important for FM Radio? I don't use this anyway...

pls help!

 

[donjamal]

i guess it has no polarity...but if u could upload a more detailed picture maybe i can see it clearly..
or search for ( as u can see the black component which has a white sign near the two condensator - it has polarity ) signs, i mean +, or a little colored circle on the component, or some cut-off and if it has one of these it has polarity.

what kind of paste did u use for the soldering? leadless or pb? it does matter.

ps : L means Inductor

 

[vanhyfte.johnny]

It's a simple inductor. You can just solder it back in. It has no polarity.
Do not shorten the contacts. The circuit will probably behave bad.

 

[lordmaxey]

hi there,

can you recommend me any "special" hardware?
With links would be great!

I only have an ordinary soldering-iron, whrere the tip is 3 times larger then the component

cheers

 

[lanigera]

Here is some of the equipment I use for such a fix:
* Weller WES51 soldering station
* Weller ETU soldering iron fine tip
* curved fine tip tweezers
* straight tip dissection probe
* 20x stereo microscope
* solder

The WES51 soldering iron is available for under US $100 online (Amazon and elsewhere) with a variety of replacement tips available for about US $5 each, and I recommend it if you will be doing much soldering. Otherwise, you can probably find a cheaper one with a fine tip, but without temperature control. When soldering and desoldering small two contact components such as your broken inductor, the best method I've found is to use a second soldering iron so you can melt the solder on both the pads at the same time. Small components are hard to handle, so tweezers and a long sharp needle / dissection tip are very helpful. It's hard to see what you are doing at that scale, so a stereo microscope is almost mandatory. AmScope has some cheap microscopes that are adequate for this purpose, or you can find a fancier used one on eBay. My only complaints with the AmScope microscope I have is that the depth of field is somewhat shallow and I need to get my face closer to the work area than I would like. You can use and lead/tin alloy or lead-free solder designed for electronics use to do a fix like this. Lead / tin alloy solder melts at a lower temperature and is much easier to work with than lead-free solder but may not be as easily available in some countries.

I can't tell for sure without a bill of materials for the phone, but based on what you've said it seems like the replacement part is a 27 nH air core inductor 0402 size such as Murata LQW15AN27NJ00D, which is easily available through Digi-Key and possibly other online electronics component vendors.