2
\$\begingroup\$

I currently have an LG V20 and its charging port is deteriorating. Unfortunately, it is out of warranty and the best price that I can find to have it professionally repaired is US$60, which is about half the cost of the phone. As such, I would like to try to repair it myself, with this replacement part (I am open to advice on a better alternative, but I don't see anything wrong with this one.).

Supplier's photo of replacement part from Amazon

I have experience soldering for plumbing, through-hole PCBs, and just bare wires. I have not, however, ever worked with surface mount components or anything this small before. I found a YouTube video that goes through the motions of such a repair, but it doesn't have the kind of detail that I need to figure out how to do this properly. At best, I could mimic what I see the person in the video doing, but that isn't ideal for obvious reasons. It is also worth noting that, according to that video, there are several heat-sensitive components (such as a piezoelectric microphone) very close to the port, making hot air a bad idea.

As such, I ask: What is the best way to replace a component of this type (with plenty of keywords so I can go and learn the techniques that I need), given that hot air is a bad idea?

EDIT: I would like to note that I have access to a fully tooled electronics lab. Tools are not an issue.

\$\endgroup\$
  • 2
    \$\begingroup\$ Unless you're prepared to spend the cost of a new phone + however long you decide to hack away at this on a learning experience I'd recommend you just bite the bullet & give the repair guy his $60. The job you're contemplating is not an easy one for a (relative) newbie and it'll be very easy for you to accidentally destroy things to the point where it'd be uneconomical for even your $60 repair guy to fix. \$\endgroup\$ – brhans Feb 12 at 16:39
  • 1
    \$\begingroup\$ Agreed, I've been SMT soldering since I was 16 and I'm not confident that I could do this job. These little connectors are absolutely awful to solder, even if it wasn't surrounded by heat sensitive components hot air is still a bad option because there are little bits of plastic in the connector that start to char and boil if you go too hot. Also on USB connectors, if you use too much flux, solder can creep into the metal housing and clog the connector. \$\endgroup\$ – Ocanath Feb 12 at 19:51
  • \$\begingroup\$ You can apply hot air to the bottom side of the board. The connector you showed cannot be soldered just by an iron, because there are some internal pins which are not accessible by iron tip. \$\endgroup\$ – Chupacabras Feb 12 at 22:48
  • \$\begingroup\$ @chupacabras The video shows it being replaced without hot air. \$\endgroup\$ – john01dav Feb 13 at 0:07
  • \$\begingroup\$ What do you mean under "replacement alternative"? For this kind of miniature electronics the replacement part MUST BE EXACT, including shroud mounts etc. Otherwise your repair won't last long. \$\endgroup\$ – Ale..chenski Mar 30 at 0:10
3
\$\begingroup\$

You cant do this without the right tools for the job. Based on your description, you also need to shunt away heat from sensitive components. Kapton tape might help. I've heard of people using aluminum foil, but thats conductive and you have a battery powered circuit. I also strongly recommend getting a microscope for electronics rework. The pitch of the pins on that connector is so small you will need magnification.

You could try removing all the solder with solder wick, but thats challenging to do with SMD components.

You could try using extra solder to heat up the entirety of the connector's pads all at once, but you run the risk of lifting pads at that point.

My personal recommendation is to use a hot air gun and shield off the sensitive components with the tape. If you try to use the wrongs tools, you will irreparably damage your phone. Also, make sure your phone is entirely backed up before attempting this. I would approach this repair as if the phone was going to be unrecoverably damaged during the rework.

Based on my understanding of your experience level working with sensitive electronics, I would also recommend practicing on something else first. The risk of damaging your phone is too high.

| improve this answer | |
\$\endgroup\$
  • \$\begingroup\$ > Based on my understanding of your experience level working with sensitive electronics, I would also recommend practicing on something else first. I agree that this would be an excellent idea. But, what should I practice on? I had the thought of just ordering dead motherboards for this phone, but there has got to be something cheaper (e.g. a PCB with a bunch of similar connections on it and no working circuit). \$\endgroup\$ – john01dav Feb 12 at 16:46
  • 2
    \$\begingroup\$ Ask around at work or friends if anyone has an old phone or tablet they don't want anymore. Chances are high of finding one. \$\endgroup\$ – rdtsc Feb 12 at 17:47
  • \$\begingroup\$ "but thats conductive and you have a battery powered circuit." For any de-soldering-soldering repairs it is imperative to disconnect any battery. To shield other components when using HEAT PENCIL (not heat GUN!), people usually use copper sticky tape covering all around.. \$\endgroup\$ – Ale..chenski Mar 30 at 0:16
0
\$\begingroup\$

To install, you could drag solder and heat would not be a problem if you do it properly in one go. But you would need some practice since if you need to go back in to fix bridging due to an overly large solder bead or just sloppy handling, that's when heat problems occur.

Big tip is better, even bigger than the work piece (2-3x) if you can fit it in. Hoof (flat conical cross section) tips are best, preferably without tinning on the side faces, just the tip. Bevel tips which are the same thing but with tinning on the sides or spoon tips (hollowed out conical cross section) are second best. The biggest difference with the hoof (hollow) and other two tips is the tips without the hollow hold the solder bead doming away from the tip face which makes optimal contact (for no bridging) much easier than the spoon tip, even though the spoon tip holds more solder.

Chisel tip will work in a pinch but makes controllingn the solder bead (and bridging) trickier. You want the solder bead to wash over the pins, but not the tip of the iron itself.

Use plenty liquid flux for both solder and desolder. Don't skimp, especially if you're not good and your dwell times are too long.

Hoof Tip:

enter image description here

Bevel Tip:

enter image description here

Spoon Tip:

enter image description here

These are what JBC calls them. Names may vary a bit.

But removing it is the part of greatest heat damage. I wouldn't do it without a blade tip that can hit all the pins at once.

Safest way for someone who doesn't know what they are doing is to use tiny cutters and just just cut all the pins and extract the component Then you can go back in to remove the soldered pins. Do you have shear cutters capable of that? I can't tell how closely spaced those pins are and have not personally laid eyes on such a cutter except for the XUron 9250ET and now obsolete Plato 170SMD. enter image description here enter image description here

These cutters also tend to be VERY expensive. The ones I mentioned are not but are on the larger end of in-between the pins cutters, but other fine-pitch cutters such as those from Erem or more exotic manufacturers cost $100+ and still might be too large.

Perhaps you can test to see if a razor can cut the thinner pins. I think the best candidate is the heavy Exacto knife handle with the 90 degree, square chisel blade that thrust you push straight down. Something like the Xacto #19 chisel blade, though that might be too wide but narrower versions exist like the #17.

it is a lot safer to start from the edge with cutters if you can rather than using a knife. lets you get away with a larger cutter. You could use a knife for an edge pin if it is too tight for cutters and once space is opened up at the edge ugo in with cutters for the rest. In this case, to cut a single pin any chisel edge is too wide. A pointed Exacto blade would be best, preferably a heavy duty one, not the super pointy dainty normal ones.

| improve this answer | |
\$\endgroup\$
  • \$\begingroup\$ I like the idea of cutting the old connector, but you'll need a very fine set of cutters. I'm sure they exist though. \$\endgroup\$ – gregb212 Feb 12 at 16:32
  • 1
    \$\begingroup\$ You have to be very careful with how you cut away the connector if you end up having to cut into the body or multiple SMT pins at once. You can end up physically torquing the soldered pins to the point that it rips the pad up from the PCB. \$\endgroup\$ – Michael Karas Feb 12 at 16:57
  • \$\begingroup\$ @MichaelKaras yeah it is a lot safer to start from the edge with cutters if you can rather than using a knife. lets you get away with a larger cutter. but that conector seems to block the edge of the row of pins though \$\endgroup\$ – DKNguyen Feb 12 at 18:59
  • \$\begingroup\$ You could use a knife for an edge pin if its too tight for cutters and once it is opened up at the edge use cutters for the rest. To cut a single pin any chisel edge is to wide. A pointed slant exacto blade would be best, preferably a heavy duty one,not the dainty normal ones \$\endgroup\$ – DKNguyen Feb 12 at 19:13

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.