Help with soldering! (fixing my MG L-Mini II)

(I hope I have this in the right, forum. Mods can feel free to move it if necessary)

One of the wires on my MG L-Mini II has gotten loose from taking the head on/off. Here is a picture.



I do not have any materials or any experience in soldering, but am thinking about giving it a go myself. I've done a little reading on soldering, but still am not sure of some things. I'm looking at getting a cheap 30W soldering iron and 1mm rosin core solder, from dealextreme.

Tell me if what I'm planning is ok: Firstly 'tin' the soldering tip. Clean the area to solder with a bit of isopropyl achohol. Heat up the existing solder where the wire is loose (do I need to remove it completely?). Add new solder and join wire to solder?

Any tips or thoughts before I go ahead with this?

I suggest that you get some scrap, an old circuit board or some copper wire, and practice on it first. Remember that you heat the wire so that the solder melts and coats it. If you just melt the solder and dribble it on then the joint will not be strong.

It helps to poke a tiny bit of solder between the iron and the work to improve the transfer of heat. But let it heat a few seconds before adding more. The solder should melt when it touches the wire and wick into the joint.

hazna said:

( Firstly 'tin' the soldering tip. Clean the area to solder with a bit of isopropyl achohol. Heat up the existing solder where the wire is loose Add new solder and join wire to solder?

Click to expand...

sounds about right to me.

you might also just borrow a soldering iron for 2 minutes?

waddup said:

sounds about right to me.

you might also just borrow a soldering iron for 2 minutes?

Click to expand...

I don't know anyone who's got a soldering iron...

I've had a few people who have PM'ed me offering to repair it, or suggest that I send it to someone locally who is willing to repair it. I'd like to thank those that have offered their help. If anyone who lives in australia is willing it repair it for me, I'm happy to pay for postage both ways.

You will probably find you can just re-work it without even needing more solder.

It's not a piece of aeronautical equipment that requires high reliability hand soldering to NASA standards, which you would struggle with anyway given just a DX 30w soldering iron.

As long as the wire is intact, simply reheat the solder it should re flow back together.

Just make sure you don't over heat everything by leaving the soldering iron in contact for longer than absolutely necessary.

Yep to all the other comments, that looks like they didn't tin the wire first or something.

Wipe it with iso on a q-tip.
Tiny, tiny, tiny smear of flux from the other end of the q-tip.
Touch it with hot iron for 1-2 seconds to reflow it all together, no added solder.

Kremer said:

Yep to all the other comments, that looks like they didn't tin the wire first or something.

Wipe it with iso on a q-tip.
Tiny, tiny, tiny smear of flux from the other end of the q-tip.
Touch it with hot iron for 1-2 seconds to reflow it all together, no added solder.

Click to expand...

the wire ends 'bluntly' and no longer makes good contact with where the solder is... will what you suggest still work? I'll try get a better photo for viewing later.

^Gurthang said:

Hazna,

Reflow work requires a good HOT iron and quick application to the joint. If the wire has lifted from the joint use a heavy needle or paperclip to press the wire back onto the joint, then quickly apply heat.

If the wire has seperated from the joint you may want to VERY carefully pull it out so you have more length to use to press the end back onto joint. Once you've got a good joint you can carefully work the wire back out of the way.

Click to expand...

How many watts soldering iron do you recommend? A website I was reading suggested 15-30W if your are new to soldering electronics.

Here's what I'm looking at buying for my job:
http://www.dealextreme.com/details.dx/sku.16027
http://www.dealextreme.com/details.dx/sku.6502
http://www.dealextreme.com/details.dx/sku.22251

Maybe some plastic tweezers as well...

Don't know about the solder but rosin core is good, I use Kester 60-40 or 63-37 [a 1 lbs spool will last just about forever]. The flux, rosin type is correct again an unknown,

The iron wattage is fine again its the quality of the device. Best advice is to practice, practice practice.... most of this work is very small so fast, accurate work is essential, otherwise you can ruin a driver or LED w/ too much heat....

The original soldering job was ill conceived/botched/crap because the leads to the emitter pads are turned 180° from the direction they need to be going! This puts undo strain on the joint and any movement from turning/twisting will break the lead. Since you already have one failed joint make sure you re-solder the second one in the correct orientation.


Since you're going the DX route, I'll give you some more links/items that will help you DIY. Don't be afraid to tackle this project because it is very simple!

1st. Don't bother with that liquid flux. Not appropriate, nor needed. You need some simple Rosin flux but that damned DX site is horrible trying to figure our what is what?!! I'm pretty sure this will be OK. You only need a tiny amount but it's vital to have additional flux for re-work/soldering in general.


2nd. Plastic(!) tweezers are out. Get this two pack.


3rd. You need a damp sponge to keep your soldering iron tip clean. You'll soak one in water when you first get it and just squeeze out the excess to use. You don't want it soaking wet as it will drop the temperature of your iron.


4th. You need solder wick to clean up the old solder. Simply place it between your iron and the solder blob and it soaks/wicks it right up. Dip it in the flux to help get it going, and do NOT keep it in place very long. It's a very quick process, in and out, so that you don't overheat the board/led.


That's the key to soldering, get in and out quickly. A repair like this should only take a few seconds per joint with a hot iron. And speaking of a hot iron, don't plug that cheap unregulated soldering iron in and just sit it aside for a long time to idle. The trick is to let it come up to temperature, maybe 3,4,5 minutes tops, do your work and then unplug it so it doesn't overheat. Unnecessary idling is what burns up the tip because it overheats and cooks the flux and this causes rapid oxidation. Not what you want when trying to learn how to solder!

..also, practice first on some stranded wire and a PCB from some electronics junk you're bound to have laying around the house. Technique is everything and the only way to get it is to practice.

Good luck.

thank you, that was really helpful. Will give it a go, when I get a chance