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plug in power supply (AC to DC adapter)

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kande04

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This must be a specialized power supply because I can't find a replacement (15VDC 400mA). It powers a video tracker device (In the Picture video tracker sold by 21best), and there was a short in the power cord that goes to the tracker, big spark when I connected it, and it now looks like I cooked the power supply rather than the tracker.

I took the tracker apart first thinking that I'd blown something in there, but everything looked okay so I tried a 12VDC 300mA power supply and it powered on. So I must have cooked the 15VDC 400mA power supply.

Is there any way to fix it, and if so, how do I get it open?
 

chuckey

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These "wall wart" power supplies often have a thermal fuse imbedded in the transformer and wired in series with the primary. So check to see if the primary is open circuit, if it is, carefully tease of the layer of tape on the transformer and fix the little fuse link that will have blown.
Frank
 

kande04

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These "wall wart" power supplies often have a thermal fuse imbedded in the transformer and wired in series with the primary. So check to see if the primary is open circuit, if it is, carefully tease of the layer of tape on the transformer and fix the little fuse link that will have blown.
Frank
Thanks, this is exactly what I needed to know.

Anyone have any ideas how to get the plastic case open? If I put it in a vise and use a big pair of pliers will it pull apart, or are they usually glued/sealed together?
 

kande04

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Stick it a vice and cut around the seam with a fine toothed "Junior " hack saw, don't let the blade slip and go in any deeper then 2mm or so.
Frank
Thanks! I hacked it open and pulled it apart and there's a thin copper wire soldered to the clip that slides over each plug connector, and that thin wire goes to the wrapped bundle of copper wires. It looks like one of those thin copper wires burned through, and that those are the only wires going to the wrapped bundle of copper wires.

So now the burned through wire is too short to re-solder to the connection, so do I need to unwind it or is there another way?

http://i1101.photobucket.com/albums/g439/kande50/15Vpowersupply.jpg

I'm a rank novice at this and this is one of my first attempts to fix anything electrical. I just recently retired so have the time to mess with it, but am just learning the basics. So I appreciate any help I can get!
 

chuckey

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I can't quite see from the picture but if that burnt out turn goes to the outside of the transformer winding then you can carefully pick up the end and unwind a turn (one turn less in 600 will not be noticed). If that end went into the centre of the winding it will be inaccessible and the transformer is scrap. The way the wire has vapourised would lead me to suspect that the transformer was either faulty or has had a massive short circuit on it. If it had a slight overload, the whole winding would have gone brown in colour. Shame it did not have the thermal fuse in it !
Frank
 

tpetar

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Buy cheap Chinese power supply, extract small transformer and use it. Its cheap, but have good transformer inside, around 300mA, also there is small stronger version with 1A, this device is 3eur.



First time is fun to be wrapped and unwrapped, but what to say if this happen again ?
 

kande04

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I can't quite see from the picture but if that burnt out turn goes to the outside of the transformer winding then you can carefully pick up the end and unwind a turn (one turn less in 600 will not be noticed). If that end went into the centre of the winding it will be inaccessible and the transformer is scrap. The way the wire has vapourised would lead me to suspect that the transformer was either faulty or has had a massive short circuit on it. If it had a slight overload, the whole winding would have gone brown in colour. Shame it did not have the thermal fuse in it !
Frank
I think it does go into the center, but am going to strip the winding and take a closer look just in case I can fix it. Probably shouldn't, because it cost less than $30 and the video tracker it powers is $250 and I don't want to toast the tracker, but 15V power supplies seem to be few and far between. (The tracker was set up to run on 10 AA batteries or this optional power supply.)

I can buy one on ebay for less than $10 including shipping, but there's something about buying directly from Hong Kong that just doesn't seem like such a great idea: http://www.ebay.com/itm/NEW-15V-400...269?pt=LH_DefaultDomain_0&hash=item5ad512b77d

Also one for a Toro trimmer that looks like it might work: http://www.ebay.com/itm/TORO-TRIMME...879?pt=LH_DefaultDomain_0&hash=item25784c0cc7

If I only knew more about what I might be buying!

- - - Updated - - -

Buy cheap Chinese power supply, extract small transformer and use it. Its cheap, but have good transformer inside, around 300mA, also there is small stronger version with 1A, this device is 3eur.
I have a 12V 300mA power supply, but don't know enough about matching power supplies up to equipment to try to run the tracker with it. Can I use a 12V 300mA without damaging a device that's designed to be powered with 15V 400mA? What if I used a 15V 1A? (Don't have one, but am curious about what could be used that wouldn't damage the device.)
 

tpetar

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I have a 12V 300mA power supply, but don't know enough about matching power supplies up to equipment to try to run the tracker with it. Can I use a 12V 300mA without damaging a device that's designed to be powered with 15V 400mA? What if I used a 15V 1A? (Don't have one, but am curious about what could be used that wouldn't damage the device.)
Then look transformer 500mA and more, you need to pay attention on voltage. You can use 5A power supply if you want, but voltage must be appropriate.

Device will pull current based on resistance in circuit. If you have stronger power supply then you need, that PSU will easily do the job without heating.

http://www.tme.eu/en/katalog/#id_ca...rams=449:27443,27453,24849,39384,24612,26406;
 

kande04

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Then look transformer 500mA and more, you need to pay attention on voltage. You can use 5A power supply if you want, but voltage must be appropriate.

Device will pull current based on resistance in circuit. If you have stronger power supply then you need, that PSU will easily do the job without heating.
Thanks! I wasn't able to repair the old power supply so ordered a 15V 400mA one from China. Unfortunately, they sent a 15V 500mA one, although it sounds like the extra 100mA shouldn't be a problem?
 

kande04

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No, its not a problem, its ok. This psu can deliver additional 100mA over 400mA if needed.
Thank you! The company I ordered it from was willing to send another one, but if this one will work I'll let them know that won't be necessary.
 

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