To TechNet Gurus:

 

I have a circuit board that is exhibiting an extremely unusual problem.
It's a basic 4 layer 1 ounce FR4 board with 7 mil traces/spaces.  The board
passed CAD netlist electrical test, checks out fine with an ohmmeter, and
nothing visual shows up with an x-ray.  The board has a 3.3 volt power
supply which is about 2 inches away from the FPGA that it drives.  

 

Somehow, the voltage is being lost between the power supply chip and the
FPGA.  When manually applying 3.3 volts with all components removed, we are
measuring a partial voltage drop (.3 to .7 volts) on some pins of the FPGA
footprint pattern that are NOT supposed to be connected at all.  Being that
there are no visible shorts, and the electrical test didn't detect anything,
we can't determine why we are loosing power.  Almost as if there was some
kind of inductance involved, but I can't se where.

 

We're at a loss.  Any ideas would greatly be appreciated.

 

Greg Goodenbury

 

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Conquest Technology, Inc.          407-359-1919

1500 Town Plaza Ct                   407-359-1918 Fax

Winter Springs, FL 32708-6224   [log in to unmask]

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