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When your simplest connector is also your weakest link: the tale of the DC power plug

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Tinus.vandeWouw
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re: When your simplest connector is also your weakest link: the tale of the DC power plug
Tinus.vandeWouw   10/28/2011 8:41:57 AM
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What may also have happened in this device (as I have experienced a number of times) is that the contact with the outer plug contact is too weak. With a spring hook you may increase the mechanical tension so that the contacts are more solid. I have also repaired many electronic devices (e.g. digital cameras) by cleaning only the battery contacts. Let's face it: all mechanical contacts (incl. solder joints) are potential quality problems!

WKetel
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re: When your simplest connector is also your weakest link: the tale of the DC power plug
WKetel   10/6/2010 10:59:14 PM
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It is indeed a product quality problem. The worst ever application was when one of the coaxial power connectors was used on a piece of crash data recording instrumentation. That unit did have a nut to hold the connection together, but the center connection would not survive very many connection cycles. Fortunately, in this application it could be installed, torqued, and left alone. But there are better choices, it is just that they cost more. You will not find those cheap connectors on any military equipment, nor on production equipment in the auto plants.

fixtureguy
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re: When your simplest connector is also your weakest link: the tale of the DC power plug
fixtureguy   10/6/2010 8:16:37 PM
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I had a similar experience involving the charger connector on my cell phone. Due to the worsening "hold it just right" phenomenon, I suspected plating wear on the connector. Once I opened the case, though, I saw that the problem was fractured solder joints on the SMD receptacle, which were easilly re-soldered. But this is not a "cheap" device -- I've used this cell phone (Kyocera 2135) over seven years now, probably much longer than the service provider had in mind. The downside is, this is not a "cool" phone. I figured that out when the grocery check-out girl told me her mom used to have one like mine!

sushantk
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re: When your simplest connector is also your weakest link: the tale of the DC power plug
sushantk   10/6/2010 2:02:28 PM
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I think the "MagSafe" connector from apple is the best in the world of power connectors. Although i am not sure if apple was the one who invented the technique. It is resistant to breaking due to any sideways force as it just dislocates on large applied force. It has good gold contacts to take care of oxidation and is polarity safe. All in all, it addresses most of the reliability concerns that plague the traditional plug-socket type of connectors.

Laser Man
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re: When your simplest connector is also your weakest link: the tale of the DC power plug
Laser Man   9/29/2010 2:10:19 PM
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Planned Obsolescence. In order to keep the account books fat, products are designed to malfunction shortly after the warranty period expires. For the unlucky majority not crafty enough to improve the fault, they have to buy a replacement product. Hence the profit model is sustained. Sometimes it backfires either from 1) word of mouth from frustrated consumers (thank the internet for this) or 2) retailers who have found one too many defective units right out of the box (there is a german music equipment maker who is infamous for this).

DH123
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re: When your simplest connector is also your weakest link: the tale of the DC power plug
DH123   9/27/2010 5:16:43 PM
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The HP ZD7000 laptop computer has a DC connector problem that is also fixable in seconds and without a soldering iron. After about 4 yrs the power supply became intermittent and examination showed it was due to poor contact at the DC connector. I opened the computer and worked my way down to the main board with DC socket and re-flowed the solder joints. However, after reassembly the problem remained and I presumed that the problem was on the cable side. I found a replacement cost for the uncommon DC jack that contained two spring prongs inside. It was then that I noticed that the prongs had weakened and were no longer making contact with the central pin of the socket. A quick realignment of the prongs with a pin fixed the problem, and that was about 2 yrs ago.

David Ashton
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re: When your simplest connector is also your weakest link: the tale of the DC power plug
David Ashton   9/25/2010 12:30:45 AM
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I've fixed so many things like this. Either (as pointed out above) the socket on the powered bit has dry joints to the PCB (automated soldering processes never get enough solder on them, and thermal cycling does the rest) or the wire near the connector from the wallwart has gone open or intermittent from being flexed (but that's unusual for something like your router that sits in the same place all the time). In either case you can usually fix it easily and cheaply - the alternative is buying a new one, so why not? The trickiest one I did was a laptop PC where I could not get at the bottom of the PCB without taking the whole thing completely to pieces - neither I nor its owner had time for that - so I got my thinnest soldering iron tip and worked between the case and the PCB to resolder the joints. It worked - owner was happy and I got a case of beer! If its on the plug on the wallwart cable, just buy a new plug. Not always possible - if so the plug usually has a moulded strain relief just above the actual connector. Carefully strip that back 1/4 inch or so to bare wires, chop 2 inches off the cable and resolder - make sure you insulate. Then put a couple of layers of heatshrink over your new joint. Not too pretty, but it might keep an essential bit of equipment gong for a bit. I learned all these tricks in a previous life in Zimbabwe, where buying a new one was not as easy as it is in the "developed" (read: throwaway) world....

ReneCardenas
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re: When your simplest connector is also your weakest link: the tale of the DC power plug
ReneCardenas   9/24/2010 10:04:34 PM
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This blog resonates with me so dearly, since couple of notebook PC that I have owned presented a premature wear prolem, that I attribute to the poor mechanical strain relief internal to the power socket that does not match the abuse in normal use from a brick hanging/anchoring excessive stress to these connectors. Note that despite attempting to reduce the stress, there always going to be some form of stress until this bricks get much lighter.

Mongo647
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re: When your simplest connector is also your weakest link: the tale of the DC power plug
Mongo647   9/24/2010 8:45:59 PM
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Ah, the troublesome wallwart! They do make them with cords for AC input too (called cord-warts) so you can get more than one into your 6-way outlet expander, otherwise you're out of luck. But mainly I write to point out that the UL or other NRTL safety certification applies to the power in the wall-wart, but not to what the wall-wart powers up. Using a wallwart does two things, makes the cable going into a lightweight little plastic box flexible enough that it doesn't become the tail wagging the dog, and it isolates the product supplier from primary liability, I mean after all, the offshore producer got the wallwart certified, right? Not to worry.

Geoff_B
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re: When your simplest connector is also your weakest link: the tale of the DC power plug
Geoff_B   9/24/2010 8:23:59 PM
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Reminds me of a computer controlled telescope I own that is powered via mini plug. Each time you set up the 'scope you go through an alignment procedure so the onboard computer can get its bearings relative to the stars. It never seems to fail that at some point during the night either the motion of the telescope causes the connection to interrupt briefly, or in the dark you snag the power lead and yank it free....in either case....you have to repeat the alignment process.

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