My Arty A7 Board is dead

[Heqing Huang]

Hi,

Looks like my board is dead. 

I was using my Arty A7 board (Arty A7-35T) to test an uart design. The board was connected to the host computer. Suddenly, the board was disconnected from the host computer and all the LEDs in the board were turned off including the power goood LED. I was uding USB power mode. I tried to disconnect the usb cable and reconnect it but it still failed.

How should I deal with this situation? Is there a way to fix the board?

Thanks,

Heqing

[DigitalConfig]

I am not certain if you have any return or repair rights from digilent if so I would suggest you take that option if possible and necessary.

But in either case the first thing I would do is try to determine the root cause.

power on then sudden power off and it wont come back on failure means it was working then now its not getting power.  Since the power supply is the USB port I would check the port by trying to use it for a different device such as a FLASH USB drive and see if that functions in the port you were using for the arty board.  if the port tests out as good then next try plugging the arty back in to that port and verify that it still does not come back on.  If it does not come on then follow the schematic path of the power with a DMM from the port connection on the board, where you should have supply voltage since the port is working, up to the point where the voltage is not present.  Since you have no power at this point and the entire board is without power ( ie no leds or anything ) you can safely assume you have a open at this point ( open meaning there is not a closed path for electrical current  to take ) and the component needs replacing or there is a burned open trace at this point on the circuit board. 

Just a Wild guess at the cause:  From your description of what occurred It sounded like you may have had a loose usb cord in the socket which may have caused a spark gap overload which effectively shorted either the ARTY board or the PC Mother Board USB component.  A second possibility is that your board came into contact with a metal object such as a screw driver, there is/was some kind of solder or metal component short, or a component was parametrically low shorting out while powered up.  if the later occurred then there may be 2 faults on the board such as a chip that got shorted by the metal and also the supply routed component or open trace which we can assume is open because of there being no power and the port being operational. 

Good Luck and Regards,

DC

[jpeyron]

Hi @Heqing Huang,

Are you using a usb hub? Have you tested the board with a different pc and a different usb cable? Have you tried powering the Arty with external power.  If you have a DMM please measure the voltage on C192, C170, C169, C176, C183, C172, C174, C178, C180 with the Arty connected.

thank you,

Jon

[Heqing Huang]

6 hours ago, DigitalConfig said:

I am not certain if you have any return or repair rights from digilent if so I would suggest you take that option if possible and necessary.

But in either case the first thing I would do is try to determine the root cause.

power on then sudden power off and it wont come back on failure means it was working then now its not getting power.  Since the power supply is the USB port I would check the port by trying to use it for a different device such as a FLASH USB drive and see if that functions in the port you were using for the arty board.  if the port tests out as good then next try plugging the arty back in to that port and verify that it still does not come back on.  If it does not come on then follow the schematic path of the power with a DMM from the port connection on the board, where you should have supply voltage since the port is working, up to the point where the voltage is not present.  Since you have no power at this point and the entire board is without power ( ie no leds or anything ) you can safely assume you have a open at this point ( open meaning there is not a closed path for electrical current  to take ) and the component needs replacing or there is a burned open trace at this point on the circuit board. 

Just a Wild guess at the cause:  From your description of what occurred It sounded like you may have had a loose usb cord in the socket which may have caused a spark gap overload which effectively shorted either the ARTY board or the PC Mother Board USB component.  A second possibility is that your board came into contact with a metal object such as a screw driver, there is/was some kind of solder or metal component short, or a component was parametrically low shorting out while powered up.  if the later occurred then there may be 2 faults on the board such as a chip that got shorted by the metal and also the supply routed component or open trace which we can assume is open because of there being no power and the port being operational. 

Good Luck and Regards,

DC

Hi DC,

Thanks for replying. The USB port on my host computer is good. I connected another device to the port and it could read the device. I tried connecting my board to another USB port and it didn't work. I also tried the external power supply and that failed too. I didn't see any burned trace or component on the board. 

I did have some metal stuff on my desk and that was close to my FPGA board. I don't remember if the board ever touched that metal stuff but that was a very possible situation.

I will use the DMM to test the board to see if I can find where goes wrong.

Thanks for your helping,

Heqing

[Heqing Huang]

46 minutes ago, jpeyron said:

Hi @Heqing Huang,

Are you using a usb hub? Have you tested the board with a different pc and a different usb cable? Have you tried powering the Arty with external power.  If you have a DMM please measure the voltage on C192, C170, C169, C176, C183, C172, C174, C178, C180 with the Arty connected.

thank you,

Jon

Hi @jpeyron

Thanks for replying.

I did try using different usb port/different cable and I also tried using external power supply. None of this worked.

I don't have a DMM now. Let me buy one and measure the voltage. I will update once I have the result.

Thanks for you helping.

Heqing

[imc_user1]

I fried a Spartan2 previously when my probe shorted two parallel pins. 

What hardware circuit can one create to prevent FPGA accidentally frying up? 
 

[DigitalConfig]

6 hours ago, imc_user1 said:

I fried a Spartan2 previously when my probe shorted two parallel pins. 

What hardware circuit can one create to prevent FPGA accidentally frying up? 
 

I recommend a custom case to house the board, I have a dozen radio shack generic project cases I purchased years ago before RS went out of business. Pmod cables can be purchased from Digilen to create custom expansion ports from within the case and other suppliers also have parts such as Power supply connectors that if you drill a hole in the case you can easily add a Plug in PS connection.

 

On ‎6‎/‎27‎/‎2018 at 2:52 PM, Heqing Huang said:

I did have some metal stuff on my desk and that was close to my FPGA board. I don't remember if the board ever touched that metal stuff but that was a very possible situation.

Note I am not saying that you did actually fry the board yourself but determine if possible the nature of the Fault.  And I would also recommend reading the Digilent Warranty terms ASAP, as it is a limited Warranty.

There are two more possibilities that I didn't mention as a root cause:  Missing Solder or Cracked/Damaged/Cold Solder creating an open circuit.  I don't believe it would be cracked/Damage/Cold Solder because that is usually created through one of the following Extreme Environmental conditions, such as high vibration environment, or exposure to fluctuation of temperature extremes repeatedly over a long period of time.  However missing solder can be a manufacturing issue due to several reasons one such as solder paste application techniques.

In any case Good luck getting your board to regain its functionality.

Regards,

DC

[imc_user1]

On 6/30/2018 at 12:41 AM, DigitalConfig said:

I recommend a custom case to house the board, I have a dozen radio shack generic project cases I purchased years ago before RS went out of business. Pmod cables can be purchased from Digilen to create custom expansion ports from within the case and other suppliers also have parts such as Power supply connectors that if you drill a hole in the case you can easily add a Plug in PS connection.

DC

Thank you DC. 

Are there any current limiter which can reduce the current when a short circuit happens like what the AC fuses do?