Help with a yanked-out wire required...

[alchemist]

A bit of a longshot this, but what the hey...

Much like the Rebel Alliance found the Death Star's one weakness, my 2 year old boy found the weakness of our treadmill, by yanking out the one exposed wire, and rendering it an expensive piece of furniture. Here's a picture...

As you can see, the red wire is just about still in place, but the black wire is gone. All that's left are a couple of tiny strands of wire above the writing CN1. Here's what the back of the board looks like.

The two wires connect to the silver blobs to the left of the D. I presume that when they made it, they threaded the wires through the board and soldered them.

My problem is, how do I reconnect the black wire? I've tried to make as much contact as I can between the "stump" of wire on the board and the stripped black wire, then taping them down. No good. If I scrape off the silver blobs, will I just destroy it, or can I re-solder it back (bear in mind I've never soldered in my life)?

Any ideas whatsoever appreciated, because I'd like it to work again, and it's too big to fit in the bin.

 

[Interference]

Re-soldering is the straightforward solution - at least for someone who has a soldering iron.

Strip back a little of the black plastic, twist the wire till there are no flying strands, heat the soldering iron, apply a little solder to the bare wire.

Now hold the soldering iron on the blob side of the board till the old solder melts. Push the wire through until it looks right. If necessary add a little more solder on the blob side.

You may need three hands

Then wrap the whole thing in duct tape, gaffa or insulating tape so it can't happen again.

 

[Vertigo]

Don't go scrapping bits off, you will probably damage it further. If you have never soldered before I would recommend finding a friend who has or going down to your local garage - I mean it. With a soldering iron it should be a pretty trivial 5 minute job and any garage mechanic will have done a bit of soldering in their time. You could take it to a proper electrical repair shop but they'd probably charge you ten times as much.

If you do it yourself you need to use a soldering iron. First clear away the old solder (the iron will tend to "suck" up the solder as it melts, then flick it off the iron). This should expose the hole the original wire went through. Clean about 3 or 4 mm of the black wire and stick it through the hole and then solder it in place with fresh solder.

If the red wire connection is looking dodgy as well then I would do the same with that one.

 

[Vertigo]

he he Inter, snap! you got in just before me!

 

[Interference]

Between us I think we managed a complete answer

 

[chrispenycate]

Do you have access to a soldering iron, or a friend with a soldering iron? I could do it with a poker and a gas ring, but it's not recommended.

You'll need some solder, and a pair if needle-nose pliers, some diagonal nippers and wire stripper are useful. but not totally essential (a solder pump's good, too, but fairly specialised.

Strip about five millimetres of the end of the black wire, and twist the strands tightly together. Heat the twist, not getting too close to the insulation. If your solder is rosin cored, just apply the solder lightly to the hot wire, where it should flow in and make everything solid. If it's making a blob, shake the wire briskly, but not over a nylon carpet (or son). If plumber's solder is used, dip the hot wire in the flux (where it should sizzle) before applying the tin.

All this could be done with a gas ring, if care taken; but the next step, cleaning the solder out of the hole in the board really needs a hot piece of metal. Worst case we hold a big nail in a pair of pliers and put that into the gas flame.

You want the solder on the back of the board to run nice and liquid, but if you get it too hot the foil will peel off the fibre-glass backing, and you'll be soldering further along the tracks. When the metal's all nice and runny, shake the board vigourously to get rid of the excess (yes, outdoors is a good place to do this). Then you can variously try blowing the junk out of the hole, grabbing the whiskers of wire with the needle-noses (or tweezers) or absorbing the solder into a wick made from a piece of stripped out braided television aerial coax screening.

When the hole is clear, thrust your prepared piece of wire through it, heat and apply a tiny quantity of solder (mainly to be sure it's hot enough) then allow to cool while holding everything still (movement at this moment can lead to dry (crystallised) joints.

If there's a longish bit of soldered wire sticking through when you've finished toenail clippers are pretty good for trimming it.

 

[Vertigo]

As always Chrispy you far outstrip us with the beautiful precision of your superior explanation. He he

Sadly I expect the biggest stopper will be the lack of a soldering iron, and if one can be borrowed then the lender could probably do a better job themselves. And looking at that board I susect buying one just for this job would be an overkill.

 

[Interference]

I definitely concur, Doctor V. Ten minute job, max, for a friend with a soldering iron.

(Most of my ten minute jobs take half an hour, but that's a different story and quite possibly a different Universe ...)

 

[alchemist]

Thanks guys. I'm glad to see you all think it's fixable. I think I'll remove the back panel tomorrow to see how mobile I can make the board and the wires, then go looking for the equipment and/or the expertise. The DIY enthusiast in me wants to learn a new skill; the brain wants to find a solder-lender.

 

[chrispenycate]

When I (bricoleur extrordinaire) started working out the steps depending on what or what wasn't likely to be available there were no other responses. But each one of those bodges (nail in a gas flame, blowing through hole with a drinking straw, using depiliation tweezers and toenail trimmers) I have done on electronic circuits, not just detector reeds (or is that a mercury switch?)

Sadly I expect the biggest stopper will be the lack of a soldering iron

Which is why my shoulder bag generally contais a small soldering iron and some solder, as well as a tiny multimeter (and two books, and my writing notebooks, and you wonder why I walk lopsided?) And, of course, I always have a Swiss army penknife…

 

[Vertigo]

I should hope so too Chrispy, perish the thought you should be without a Swiss Army knife (I never had a real one and always wanted one ). And yes, I have done similar botch jobs in my time but hey they work (like tuning old contact breaker engines with cigarette papers, those were the days). And mercury switch was my thought too.

Alchemist why not combine the two; friend with a soldering iron shows you how to do it - new skill learned (or at least started).

Oh and Int. Doctor! I wish! Isn't it funny, back in the day I couldn't wait to get out of Uni and into the "real world", now I wish I'd never left!

 

[Metryq]

It's already been mentioned, but I was going to comment that the component looks like a reed switch. That means the board is probably part of a safety switch—some cover on the machine must be closed in order for the machine to run. Somewhere on the cover there is a magnet that will cause the reed switch (the thin glass tube) to close, thus allowing the machine to run. So—

Yes the fix should be very easy. I'm guessing that the red and black wires run to a plastic connector elsewhere that can be unplugged in order to replace the board and reed switch, if necessary. Of course, one could easily "hotwire" the machine and bypass the safety by baring the red and black wires and twisting them together. But I'd advise against it. Some machines are over-engineered for safety, but with a young 'un around, I wouldn't bypass any safeties.

I think the ultimate Underwriters Lab would be a kindergarten, or even a college. ("That's a video camera, not a soccer ball!") If the device can survive those trials, it will survive anything.

 

[alchemist]

Good spot, Metyrq. There is a magnetised safety, and you're right, I wouldn't risk hotwiring. I have now removed the wires, and identified a solderer (alchemissus's aunt, a former physics teacher), so we just have to pay her a visit now.

Edit: and when I get it done, I'm going to tape it up to within an inch of its life.

 

[Interference]

Score! .

 

[Ursa major]

Don't you mean, "Result!"?

(With Score, you might get one of the Swiss versions: either ScoreCH, or an unwanted scratch made by that army knife....)







But hoorah for aunts able to wield a soldering iron!

 

[Interference]

I'm not sure what I meant, I was just trying to be trendy and yoof-ful.

 

[chrispenycate]

Or, as they still say in French, "branché" (= plugged in).

 

[Vertigo]

Does indeed sound like a solution!