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I fried a card reader

Imavision

Mar 29, 2017
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The card reader in my computer never worked right, at least the SD card part of it, the only part I ever used. It woudn't turn on when inserting a card, or it wouldn't read it... So I decided to open it up. I saw that to turn the device on a pin of the AU6476 controller needs to be shorted to ground. For some reason, the contact was incredibly intermittent and unreliable when a card was inserted which is the reason it never worked right. So I had an idea, I would connect a wire to that pin, and when I had to use the card reader I would insert the SD card in, and then I would connect the wire from the controller to ground. The wire would come out of my computer's case for easy operation. I tested my idea with the card reader out of the PC and it worked perfectly! Nice I would finally be able to use it without any problems. But things didn't go as planned... While re-inserting the card reader into my computer's case, a disaster happened. The computer was on while I was doing this. The card reader was connected to the motherboard. I slid the card reader into the case, and my idea was to have my added on/off wire come out of the front of the case. But, the wire accidentally got stuck in a hole of the power supply. I couldn't get it out in time, it touched something in there, sparked, and then the computer behaved erratically. I turned it off. The computer didn't suffer anything at all but now all the card reader does when it is plugged in is get extremely hot. So, it's fried. The controller got a direct connection with the heat sink of a transistor in the power supply, that's the only thing I can see that it could've come in contact with. Oh and as a result the circuit board trace I was using also blew up.

I already bought a new card reader but I wonder if this one could be repaired. I find things like this fascinating... There isn't much on the circuit board. A controller, an oscillator, an LED, some fuses, some resistors and some capacitors. Does anyone know if only the controller got fried or if other components on the board also likely died? Let's say only the controller got fried. Would a person even be able to replace it? It's a small 100 pins surface-mount integrated circuit. It seems pretty impossible to replace by hand to me. But I could be wrong?

http://img4.hostingpics.net/pics/922094friedcardreader.jpg
 

Harald Kapp

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The computer was on while I was doing this.
Bad idea. I'm sure you learned something from this experience, did you not?

Does anyone know if only the controller got fried or if other components on the board also likely died?
Nobody will be able to judge this without a deep inspection of the board. Most probably at least the controller got fried.

Would a person even be able to replace it?
In principle: yes. You'll need a steady hand and a soldering iron with a very fine tip.

A repair imho isn't worth the effort. You may even pay more for teh replacement controller than you paid for the new card reader in total.
 

Imavision

Mar 29, 2017
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Thanks for the quality reply! I actually did not expect to receive any replies at all, because it's a cheap card reader, who cares is what most people probably think...

Yes. I'm actually usually very careful when it comes to stuff like this... But wow I did not expect that to happen, a wire to get stuck in the hole of a power supply. Shows that anything can happen at anytime huh.

Okay, so it is a possibility that the controller isn't the only thing that got fried... How would someone find the answer to that? Remove each component and test them?

Very interesting. So someone with the right tools and skill could replace it.

I know that it isn't worth the effort. But if replacing the controller is all it could take to repair the card reader (of course I would have to re-add my modification though...) it'd be great because of two things. 1, It'd be repaired (obviously). And 2, it would be a great exercise in surface-mount soldering. I currently neither have the right tools, or the right skill to do surface-mount soldering, but if a small 100-pin integrated circuit like that can be replaced, then replacing smaller, simpler things must not be as hard as I imagine it to be.

Uhmmm with all that said, I think I'm just gonna put this thing in a box and forget about it...
 

Harald Kapp

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How would someone find the answer to that? Remove each component and test them?
One way to do it.
Replace components one by one until the reader works again is another way.
Check for any visual defects is a good starting point in any case.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Very interesting. So someone with the right tools and skill could replace it.

And the correct replacement parts. This may be the largest stumbling block (identification, availability, and price).
 
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