CF card in adapter hot enough to burn fingers, melt plastic

<p>I have an original Canon 5D that uses the older compact flash cards. The adapter I use plugs straight into the USB port on my full-size laptop and I've had the adapter for about 8.5 years. This evening I was transferring some files and left the adapter plugged into the PC while I edited a couple of shots. When I touched the card reader to unplug it from the PC, it was hot enough to burn my fingers and there a two little melted dimples in the plastic of the card reader/adapter. It's not a Samsung Galaxy Note 7, but I'm throwing the reader in the trash. Has anyone else ever had this happen to them and, if so, what do you think is going on?<br>

Rob</p>

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<p> It's not a Samsung Galaxy Note 7,<br>

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<p>Darn, you used my line! That is so weird and scary. </p>

It is strange. I have used USB and I am sure the DC voltage is low enough that it is remarkable that it could do this sort of thing. I even have a USB hub that relies on AC power... We need help from the electronics engineers in the community. LIke, Is this even possible? Help! By the way, after many years with Sandisk readers I now am a strong Lexar card reader supporter. Those wires can get mashed up after in and out extraction efforts. (If I had to wildly guess it sounds like some kind of such a contact wires short..but that is still a long shot from a layperson, and lucky your card was not ruined like one of mine with contact failures).

<p>Sounds like a short. Amps can really go up with a short even though there's low voltage. </p>

<p>amps (I) = voltage (E) ÷ resistance ®. (Ohm's Law) If resistance is a short (no resistance in effect, you're dividing by 0 so the results are that amps are maxed out causing a lot of heat. </p>

<p>USB ports supply 5 VDC and up to 4 amps. That's 20 watts. Ever touch a 20 watt light bulb? Card readers and cards can get warm to the touch, but I've never had one get to the point you describe. Something is deffective, probably due to a bent pin or something.</p>

<p>The temperature generated is inversely proportional to the area over which the power is dissipated. "Hot" is a subjective term. A small short can get red hot. An object at 60 C (140 F) is too hot to touch, continuously.</p>

<p>Where was the adapter laying? My Laptop has the fan's exhaust not too distant from the USB ports. But I suppose something else must have gone wrong too inside your reader.</p>

 

<p>The card reader hangs out in "clear air" when plugged into the USB port - and nowhere near the fan. The fan exhaust on this PC is not nearly warm enough to cause the melt-down. I'm sure it was an internal short as described above. We travel full-time in our RV so I'll just use a USB cable to the camera to download images until we alight someplace long enough to order a new card reader. Thanks for all the responses, everyone.<br>

Rob</p>

<p>Order two. Like most photo gear, it's good to have a backup. I use a universal USB3 reader made by Kingston. It handles CF, SD and micro-SD cards, plus another slot I don't recognize. At this point I have at least three - on my desk, camera bag and bag I use for audio gear. Don't forget cables too.</p>

<p>The power levels and temperatures that modern electronics are designed to run at are sometimes pretty amazing. </p>

<p>There are microprocessors designed to run at 100W or more. (That is, 100 amps at 1.0 volts.) Those are fan cooled, though. That was about 10 years ago, so maybe more now. </p>

<p>Also, it isn't unusual to have a linear voltage regulator that dissipates the rest as heat. Those can get pretty hot, though usually with a heat sink at higher power levels. It might be that your adapter has one of those, and you are feeling the heat from the regulator. </p>

<p>There are voltage regulators designed to run at 125C or 150C:</p>

<p>http://pdf1.alldatasheet.com/datasheet-pdf/view/8605/NSC/LM320.html</p>

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