How to bring up FPGA board with short in the power rails.

Hi Anand,

Thank you for the message. What I have done so far:

Method -1. I have used Kelvin probe and the smallest resistance was detected below the FPGA on few decoupling capacitors .

it seems something like 10 mohm. (the ohm-meter has been zero with probes shorted)

Method -2 We have far end infrared camera and we are using regularly for this kind of issues.

The problem with this is that if we have +V ---resistor ---- short ---- GND the resistor is heating not the short.

In this particular case the main suspect so far is the FPGA (component or the soldering). The FPGA is heating a bit but not much.

if we apply 10Watts of the power input of this board I think something like 1, 2 Watts is dissipated by the FPGA the rest is dissipated mostly by the DC-DC regulators on this board (mainly +2.5V, +0.9V, +1.5V). Those heat a lot. At this point we have voltages on the rails like this :

+2.5V - 0.3V

+0.9V - 0.1V

+1.5V - 0.1V

Method - 3 Yes we have removed some of the components for the DC-DC regulators. Still short in the power rails. This is pretty big board and there are lot of the components.

I think we will try to use Method 1 a bit more and probably the next step is to un-solder the FPGA.

Any ideas will be greatly appreciated!

Best Regards

Dimitar