Defective Adafruit Rfid breakout board and 4.3" display

[John.R]

I recently purchased the Rfid Breakout board kit, which I received in the mail today and soldered together, then went through the tutorial on how to connect it to the Raspberry Pi. However, when I connected the wires to the ftdi pins, the power led does not light. I have tried powering it directly from the Adafruit console cable as well and still the led did not light. I am hoping I might be able to get a replacement. I am using this as part of my Capstone project for college and my budget is starting to stretch, so I would be grateful if I could get a replacement board as opposed to purchasing another. I must say I am slightly surprised at the defective device. Everything else I have ever ordered from Adafruit has been of superior quality. Any help in this matter is greatly appreciated.

[adafruit_support_mike]

Don't worry.. we don't operate on the "pay us for one, and if it's defective you can pay us for another" business model.

Just to cover the obvious things though, could you post a photo of your setup? That way we can double check it for anything that might be wrong (though there isn't much you can mis-install on one of those puppies), run you through a couple of diagnostic tests, and give you a pre-built support file when the folks who handle returns get involved.

One possibility could save a lot of time: the power LED might be bad. Do you get proper voltages at the 5v and 3.3v pins on the end of the breakout? If so, can you get a connection and pass information to it normally? The answer to that will probably be "no", but it can't hurt to try.

[John.R]

I did happen to test the voltage across the power led and the voltage was 0.6ish volts if I remember correctly. I also installed libnfc on my RPi and tried the nfc-poll command and it returned the error that it was unable to open nfc device.

[adafruit_support_mike]

I did happen to test the voltage across the power led and the voltage was 0.6ish volts if I remember correctly.

That's a bit odd.. an LED's forward voltage is usually at least 1.2v. What voltage do you see across the LED and resistor? I don't have an NFC breakout where I can lay hands on it right now, but the resistor should be right next to the LED.

Also, just for the sake of confirming basic assumptions, what voltages do you see at the 5v and 3.3v pins?

I also installed libnfc on my RPi and tried the nfc-poll command and it returned the error that it was unable to open nfc device.

Fair enough. We've ruled out, "it works, the LED is just dead".

That nonzero-but-low voltage across the LED makes me wonder whether the board might be starved for current. Readings from the 5v and 3.3v pins should give us more insight on that. Again, if you can post a photo of the breakout as you have it wired, I'll be able to point things out more specifically.

[John.R]

There is continuity across all the 5v pins and I know the power source is fine because I have used it with the GPS breakout board successfully. None of the ground pins have continuity to any of the other ground pins though, which I find odd, and may may be part of the problem, but I know it isn't the solder points. I don't know about the voltage at the 3.3v pin though, as I was using the uart pins. Even with the adafruit USB to TTL serial cable, the power led still wouldn't light.

[John.R]

So apparently this is just not my lucky week. I received my shipment today which contained the http://www.adafruit.com/products/946 4.3" TFT-LCD "Coolr" Monitor, which was Dead On Arrival. I hooked it up to my 12 volt DC power supply using the included plug adapter with the in-line fuse (which I did check and was fine) and turned on the power and plugged into my RPi and got a whole lot of nothing. No backlight, no Raspberry logo, nadda. I tried two other power supplies as well and hooked the input to my brother's play station to test it wasn't a bad connector on my RPi. Still nothing. My hope is that I can get a replacement for this as well. Never fear though, I still have faith in Adafruit. I believe this was a manufacturer defect. I mean, the instruction "manual" says they use precision parts and high quality products but, well, just look at the attached picture and maybe you will see where I am going with this. (Sorry, just a bit of humor I couldn't resist)

[adafruit_support_mike]

There is continuity across all the 5v pins and I know the power source is fine because I have used it with the GPS breakout board successfully. None of the ground pins have continuity to any of the other ground pins though, which I find odd, and may may be part of the problem,

Yeah, lack of continuity between the ground pins is a problem, and a very strong candidate for being *the* problem. If one of your supply wires is isolated from the rest of the circuit, nothing will work.

but I know it isn't the solder points.

That's a statement I'd never make about my own joints, and I'm pretty good with an iron. Every once in a while a cold joint looks perfectly normal. The first rule of debugging is "if you haven't measured it, it isn't true."

Let's do a quick sanity check on the supply rails:

First, measure the voltage between the 5v0 and GND pins on your Pi Cobbler (to the left in the picture). I fully expect you'll see 5v, but we have to tick that item off as having been measured before we look at the connections further downstream.

Second, disconnect the red and black jumpers from the RFID breakout and confirm that you're indeed getting 5v through the wires. There are any number of ways for a jumper connection to fail, especially when you're working with a breadboard.

Once you've confirmed a 5v potential across the female ends of the jumpers, connect the GND jumper to another GND pin on the breakout and the 5v jumper to one of the pins labeled 5v0. Take a voltage reading across the short ends of the pins sticking out the other side of the PCB. The goal is to verify that a 5v supply is indeed reaching the pads on the breakout.

Do that for all the 5v0 pins, then move the GND jumper to another GND pin on the breakout, and run the series of 5v connections again. The goal is to show that the board doesn't work for any possible combination of supply connections (I think there are nine permutations) with the supply voltage confirmed at the pads. If that process 'fails', it means you'll have gotten the board to work. If the board doesn't work for any combination of supply connections, it's a clunker and we definitely owe you a new one.. and probably need to double-check the test harness/process for those boards.

[John.R]

First, measure the voltage between the 5v0 and GND pins on your Pi Cobbler (to the left in the picture). I fully expect you'll see 5v, but we have to tick that item off as having been measured before we look at the connections further downstream.

Second, disconnect the red and black jumpers from the RFID breakout and confirm that you're indeed getting 5v through the wires. There are any number of ways for a jumper connection to fail, especially when you're working with a breadboard.

Once you've confirmed a 5v potential across the female ends of the jumpers, connect the GND jumper to another GND pin on the breakout and the 5v jumper to one of the pins labeled 5v0. Take a voltage reading across the short ends of the pins sticking out the other side of the PCB. The goal is to verify that a 5v supply is indeed reaching the pads on the breakout.

Do that for all the 5v0 pins, then move the GND jumper to another GND pin on the breakout, and run the series of 5v connections again. The goal is to show that the board doesn't work for any possible combination of supply connections (I think there are nine permutations) with the supply voltage confirmed at the pads. If that process 'fails', it means you'll have gotten the board to work.

That was actually more or less the second thing that I did, after I went and re-soldered the header rows to rule that out as the problem.

[adafruit_support_mike]

That was actually more or less the second thing that I did, after I went and re-soldered the header rows to rule that out as the problem.

Okay. Confirmed lack of function for all supply connections is good enough for me, especially combined with the TFT. You've been through enough.

Contact support@adafruit.com with a link to this thread and they'll do their magic.

Also, subject to your approval, I'll add the following note:

Support: when you pull the replacements would you please power them and test them to make absolutely sure they work before shipping? The "what are the odds of that?" gremlin has already made an appearance here, and I don't want this poor guy to get bitten again. You're wonderful, love you, I owe you cookies and/or beer (your choice) for this one.-- Mike

[John.R]

Also, subject to your approval, I'll add the following note:

Support: when you pull the replacements would you please power them and test them to make absolutely sure they work before shipping? The "what are the odds of that?" gremlin has already made an appearance here, and I don't want this poor guy to get bitten again. You're wonderful, love you, I owe you cookies and/or beer (your choice) for this one.-- Mike

Note approved, and thank you for your trouble. Also, should I create a new thread for the 4.3 inch display that was DOA, or does this combined thread work for that, and what would I need to do to get that replaced? Sorry for being sch a problem magnet, hehe.

[adafruit_support_mike]

Also, should I create a new thread for the 4.3 inch display that was DOA, or does this combined thread work for that, and what would I need to do to get that replaced?

Nope, this is me approving replacements for both the RFID breakout and the 4.3" display. You took reasonable steps to ensure proper power to the display, and there isn't much to debug beyond that.

Sorry for being sch a problem magnet, hehe.

If you'd done anything to deserve the trouble, we'd be having a different conversation.

Situations like this are statistically inevitable, but that isn't much comfort when you're on the receiving end of one. We can't promise that nothing will ever go wrong (would love to be able to), but when we do get an outlier we can roll up our sleeves and make things right.

[John.R]

Also, should I create a new thread for the 4.3 inch display that was DOA, or does this combined thread work for that, and what would I need to do to get that replaced?

Nope, this is me approving replacements for both the RFID breakout and the 4.3" display. You took reasonable steps to ensure proper power to the display, and there isn't much to debug beyond that.

Sorry for being sch a problem magnet, hehe.

If you'd done anything to deserve the trouble, we'd be having a different conversation.

Situations like this are statistically inevitable, but that isn't much comfort when you're on the receiving end of one. We can't promise that nothing will ever go wrong (would love to be able to), but when we do get an outlier we can roll up our sleeves and make things right.

You have been extremely helpful through all of this and I must say I greatly appreciate it all. I can most certainly say I will be recommending Adafruit to others, and I happen to know a few other students thinking about incorporating a Raspberry Pi in their capstone projects, so I'll see if I can't send them your way