SD Card

roy66 · 2007/11/03

This one should be quite interesting and tricky.

My SD card is now always locked so unable to transfer data.
This reason for this is that the small locking tab broke off.

I have opened the card but can't find any switching pieces at all.

I imagine that a couple of contacts need to be mated for it to become unlocked and this might be accomplished with either some aluminum foil or a pass of solder.

Any Help?

Roy66

Dennis L · 2007/11/05

Tom's Hardware - SD Card Reader says the card is write-protected
See the following response from poster's ....

oldsaw .... An SD interface includes a tiny copper finger which the write-enabling tab of an inserted SD card depresses onto another copper contact thus closing the circuit which enables the writing to take place. I suspect that that tab inside your SD reader is broken, bent, or somehow inoperable.
Click to expand...

frr .... Indeed. I used to think that the write-protect tab operated a switch inside the card. Not true - the tab is a purely mechanical flipper, with no electric connection inside the card. Instead, it toggles (or fails to toggle) an electro-mechanical switch in the SD card reader. Oh my, even the venerable floppy drives used to have an optical sensor for the write-protect tab, and I don't remember ever meeting a flawed write-protect sensor in a floppy drive... Whereas with the ultra-modern SD media, it seems to be a popular flaw :-/

Taping over the write-protect tab on the SD card may indeed help, if the mechanical switch inside the reader is flawed in exactly the right way. In my case, it was flawed worse.

On my Fujitsu Siemens notebook, otherwise an excellent reliable machine, I managed to find out that the metallic finger in the slot is free-floating when the slot is empty, but gets grounded if the finger is pressed.
Next, I was lucky several times. Without voiding any warranty sticker, I managed to find the right hood on the bottom of the notebook, which revealed access to the CPU, RAM and basically the whole motherboard, including the SMT pins of the SD reader socket. I quickly found the sensor pin, it was the left-most pin on the socket. And indeed, if I inserted an actual card, the sensor kept trying to close, but remained open most of the time.

Then I finally I got the idea that I could just short the pin to ground "out of band ". Put a very sharp tip on my soldering iron, got about 1 cm of hairline wire (a single strand from a piece of left-over stranded wire), and did the micro-surgery. I merely needed to cross a narrow gap between the sensor trace and a nearby ground plane, and I zapped my piece of wire to the right pins of two suitable SMT devices, which provided uncovered tin, easy to solder.

Guess what, the SD card isn't write protected anymore, even if I toggle the tab on the card to the "locked" position. Who cares about the write-protection anyway

Thanks a lot, everyone, for posting your comments about the tape-over trick, and especially about the "sensor finger ". That got me started. Your information has saved me from several days without my notebook, and possibly from a replacement of my known-good rock-solid motherboard (if it ain't broke, don't fix it).
Click to expand...

roy66 · 2007/11/05

Indeed. I used to think that the write-protect tab operated a switch inside the card. Not true - the tab is a purely mechanical flipper, with no electric connection inside the card. Instead, it toggles (or fails to toggle) an electro-mechanical switch in the SD card reader. Oh my, even the venerable floppy drives used to have an optical sensor for the write-protect tab
Click to expand...

Thanks very much for this information which has proved to be the solution to the problem.

roy66

Dennis L · 2007/11/05

Glad to help.

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SD Card

roy66 Well-Known Member Thread Starter

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roy66 Well-Known Member Thread Starter

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