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I have a soldering iron. Ph34r. - 'Twas brillig, and the slithy toves did gyre and gimble in the wabe [entries|archive|friends|userinfo]
Thomas

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I have a soldering iron. Ph34r. [Sunday 21st June 2009 at 9:48 pm]
Thomas

boggyb
[Tags|]
[Feeling |accomplishedaccomplished]

It's really disappointing that so many people now will just bin broken devices, without even considering trying to repair them. So it was rather satisfying to discover that my electronics-fu hadn't degraded too much over the years, and to successfully repair two devices.

First victim casualty was a Charg-E (a mini r/c car), mainly as a test that my soldering skills hadn't evaporated. The antenna wire had broken where it was soldered to a small tag, giving it an effective radio range of 2 metres. So, heat it up and suck all the old solder away. Strip the wire, resolder with new lead-free stuff (no-one seems to stock real solder anymore). The joint doesn't look spectacularly good, but does it work? Put the whole thing back together and the signal range is now at least the length of my flat. Result! Now to get a replacement ni-cad for it...

The second victim patient was my right computer speaker. After prodding it for a bit and unsuccessfully trying to presuade a bead of solder to jump across the gap, I chopped off a 2cm length of solder and tacked it down either side of the break. The joints look nice and shiny, the resistance across it is low (and I've previously measured the current draw on the track as being a few dozen mA, so it's unlikey to heat up), and most importantly I'm listening to James May on the Moon right now with them. Yay!
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Comments:
[User Picture]From: olego
Monday 22nd June 2009 at 8:45 am (UTC)
What's wrong with lead-free solder? It's much easier for n00bs like me, who pick up a single item at the store, and go home?
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[User Picture]From: tau_iota_mu_c
Monday 22nd June 2009 at 11:26 am (UTC)
Lead free solder is why modern electronics only lasts a few years before tin whiskers cause open or short circuits where they are generally not desired. Like the aforementioned aerial connection. Or that *bastard* of a molex connector that worked its way to to front panel of my LCD monitor. Oh, have I mentioned that clip together cases, instead of using screws, are the work of Senator Palin herself?
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[User Picture]From: boggyb
Monday 22nd June 2009 at 4:56 pm (UTC)
Both of these are easily old enough to predate RoHS and lead-free solder - the speakers are 13 years old, the r/c car is easily ten. I'm not sure what caused the failure on the speakers, but the antenna connection probably got broken when I had the car open for something or other.

The lead-free solder I picked up is actually 99.3% tin with 0.7% copper (I thought lead-free stuff had a small amount of silver, but apparently not always), and has a melting point about 40°C higher than real solder.

That molex connector did what? I'm aware of tin whiskers, but that must have been something special.
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[User Picture]From: tau_iota_mu_c
Tuesday 23rd June 2009 at 7:57 am (UTC)
Drat, can't find the reference, but there is one common alloy used instead of SnPb that was found to greatly increase the risk over even plain Sn, and I have a feeling it was the alloy of SnCu.

The tinned ends of the molex cable developed whiskers, which then became contageous and spread to the surface mounted connector. This was in a 3 year old LCD monitor.
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[User Picture]From: olego
Monday 22nd June 2009 at 5:34 pm (UTC)
Senator Palin, really? Do tell!
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