Nexys 4 DDR board stopped working

[rjk1993]

Hello, I'm working on a project for college using my Nexys 4 DDR. I was trying to wire up a keypad to the PMOD connections on the board for the past couple of hours, but the board just, out of the blue, completely shut down, and I haven't been able to get it to start back up again. I have no idea what to do, and I'm a tad bit terrified that it's completely busted. Can anyone lend a hand? I've been using the board for about half a year

[Bianca]

Hello @rjk1993,

Can you please tell me if you have any hot components on your board? Please look on the bottom and tell me if D15 is hot or if  you have hot power supplies. You can check IC17, IC22 and look also at IC8. (FPGA)

Also I want to measure some voltages on R287 (you can find it on the back of the board in top right corner) and C180 (big capacitor near big coil on the back).

 

Please give me a detailed description of what you did how were you connections made? A drawing of what you tried to connect would help. also, what kind of keypad were you trying to connect? 

Best regards,

Bianca

[rjk1993]

31 minutes ago, Bianca said:

Hello @rjk1993,

Can you please tell me if you have any hot components on your board? Please look on the bottom and tell me if D15 is hot or if  you have hot power supplies. You can check IC17, IC22 and look also at IC8. (FPGA)

Also I want to measure some voltages on R287 (you can find it on the back of the board in top right corner) and C180 (big capacitor near big coil on the back).

 

Please give me a detailed description of what you did how were you connections made? A drawing of what you tried to connect would help. also, what kind of keypad were you trying to connect? 

Best regards,

Bianca

Hi,

Yeah, none of the parts on the board felt hot whatsoever, including D15. As for voltages, I did get a voltage response of like, 4 V, I might not be using this multimeter correctly, but I did get a response from R287. Not so much with C180

 

This is the keypad I was working with

http://www.resistorpark.com/arduino-keypad-matrix-4x4/?utm_medium=googleshopping&utm_source=bc&gclid=Cj0KEQjw5YfHBRDzjNnioYq3_swBEiQArj4pdFz_YVDvt-pV1fbaPlnCuLAQMNsAM3vK3CJnGgaZE1gaAnNm8P8HAQ

 

The pins were all connected to the Pmod ports, I tried it with multiple ports, but I always connected the pins to the rightmost 8 pins of the Pmod port, which from what I understand, looking at the manual, are the logic ports. I was gonna try hooking the keypad onto a breadboard with resistors, but the board turned off before I could.

[Bianca]

Please measure on C178 as well.  You can find it just above L1 (the big coil). Was your board powered by USB or by an external PS? If you used an external PS can you give me its characteristics?

Regards,

Bianca

[D@n]

@rjk1993,

I'm not the real tech-support, but let me ask the really basic question: does the board have problems even when the keyboard is disconnected?

Dan

[rjk1993]

Yeah, the board still has problems without anything connected. I was powering it with a USB. C178 doesn't show any voltage measurement either

[Bianca]

Ok, this might be a good sign....please take off D16 from your board and power it through USB and see if it works. You didn't tell me how you powered the board. If you used external power supply or from the USB.

Best regards,

Bianca

[rjk1993]

Is D16 the chip on the upper right of the back? not sure how I take it off, sorry, completely new to these things!

The USB powered the board, haven't touched the external supply.

[Bianca]

Yes. It is on the upper right. In the picture below you'll see it already taken down. You'll need a soldering iron or something to melt the flux and remove the diode with some tweezers. If you are not sure what are you doing, maybe you could ask some teacher to help you or some one with a bit of experience to make sure you won't do anything worse.

At this point something is burned on your board due an over-voltage or a short circuit. The fact that you have some voltage at input but not after the diode tells me that the diode might be burned and you might be able to save your board. If the diode is not the issue then your regulator is burned and there isn't much you can do about this. This is why I keep asking you how did you power the board and what exactly have you connected and where to see what has happened to your board.

Best regards,

Bianca

[rjk1993]

Okay, ill try that. Thank you for the help, hopefully i can get things working again.