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Author Topic: LC Studio Card Reader - BAD PCB  (Read 3858 times)
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I recently received an SD card reader made by LC Studios. The reader did not work on my Mega 2560 but the GPS logging shield was OK. The scope showed very noisy signals from the reader and poor 3V3 on the card. The reader did work if connected directly to the Mega 3V3 line. Closer examination of the card and the sellers schematic shows pin 1 of the regulator chip, one end of C3, and one end of C4 are connected. However, they are floating with no connection to ground as it should be. When I ground this line, the reader works from the Mega 5V0 line, as it should.

There are two easy fixes for this problem. First, feed 3V3 from the Arduino to the 3V3 pin on the reader. This alone will solve the operational problem. A better solution is to ground the floating line, as it should be. Scrape some paint from the top ground plane just under the 'O' in Studio to expose some copper. Connect a short jumper wire from pin 1 of the regulator, pin closest to back of card socket, to the exposed copper.

Surprisingly, the sellers schematic shows a missing ground symbol along the bottom of the regulator, C3, and C4. The circuit and board designer is the culprit in this case.

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Hello. I am using the same garbage... mine works, for now (with little magic)

Check out this post from fat16lib in my thread: http://arduino.cc/forum/index.php/topic,122098.msg923701.html#msg923701

I am getting really frustrated from all the problems with cheap chinese hardware...
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I've also had some bad hardware other than this one. They're not doing a very good job of QC or keeping up with the latest Arduino IDE, especially in LCD backpacks. I found this reader is also sensitive to the level shifter values. I'm using the 74x125 taken from my GPS logger shield and duplicating some of the circuitry. I'll be switching to the Adafruit Micro-SD reader as it should be a simple wire-to-pin plug-in job. I'm using mine on a Mega 2560.

The problem goes back to the schematic designer. They left out the ground connection to the regulator and it's two filter caps. The board layout just followed the schematic so it's also bad. Apparently, nobody bothered to see if the thing worked. Using a 3V3 supply, it's fine, but using 5V0, it won't work. By adding a short jumper wire from pin 1 of the regulator to a scraped off ground area under the logo, the reader works OK.
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Quote
I've also had some bad hardware other than this one. They're not doing a very good job of QC or keeping up with the latest Arduino IDE, especially in LCD backpacks.
But, you did save a few pennies, right?
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After the addition of a 6mm piece of bare wire, yes, about 75%.
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Lormaison
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Hi everybody,

I found the same problem with this reader and more and more :
http://arduino.cc/forum/index.php/topic,125973.new.html#new
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Quidquid agis, prudenter agas, et respice finem !

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Am having difficulties with error 'initialization failed', have now tried 2 Lucas Studio cards, have wired them in and out so many times that once should have worked for me.
Have tried using SD Format on my 8GB card.
Have tried both in Mega ADK and a Duemillanove and no luck.

Have tried the mod recommended here;  to connect Pin 1 of Voltage Regulator to the ground plane on rear side and that then shorts out everything totally.
So if you do this beware   You may well take out your PC usb port!!!

To be clear - I wired the pin on the voltage regulator which is the pin closest to the edge connector pins to teh rear ground plane and everything dies, a dead short.

I do find it strange that now End of September 2013 they still sell a card with such a bug !  ( agree although that anything might be possible )

Have connected an LED to CS signal just to make sure it tickles when accessing sd card and yes it does.

As board has 5v I have presumed that Lucas SD signal pins will work ok on 5v TTL logic, there are circuits on the web showing straight though TTL wiring is ok and others talk of diodes to make voltage drop to 3.3v, most confusing !  There surely can not be 2 different methodologies !

Any one got any more insight, very grateful to hear your knowledge.

 



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I have an LC Studio labeled reader that works fine with 5v and 3.3v.  The first post mentioned "noise" and that the caps for the regulator were not grounded.  C3(input and other side to ground) C4(output and other side to ground).  My LC Studio has proper connections, proper grounds and I don't have issues.

Check the LM1117 regulator datasheet pinouts: mine is (1 Gnd, 2-Vout, 3-Vin).  You might have shorted the supply to ground as the schematic pins are not left to right with the datasheet.  Always check datasheet, and test with dmm if you can.

If you're using sdfat check the "troubleshooting.txt" in the lib directory.  Your card could be an issue as well.  Try others if you have them.  Sometimes it's hit or miss with the cards.  I haven't used anything >4gb.
Also, I find you must use SPI_HALF_SPEED with these adapters.

Posting code might help too.

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