By a quick guess:
The D9 is a Schottky diode (low Vf) to protect against reverse polarity,
while C12 is the filtering capacitor for input of the adjacent voltage
regulator. It is of tantalum type and does not withstand to be
over-voltage or reverse polarized. When the capacitor is reverse
polarized, it breaks and behaves as a short circuit, leading to
self-burning. That might happened (by connecting more than 16V) and the
short in capacitor lead to high current over it, and the D9 diode.
Another scenario - the diode might get broken by high reverse voltage,
and it allowed to pass that to the capacitor, leading to failure of both.
Quick solution: replace both C12 and D9 with new components, and measure
if the C14 (fourth from bottom) is in parallel with C12 - if yes,
replace that to, since it can be half-damaged and burn in short time
after a voltage is reconnected.
Then try to power up the board, ideally with a current limiting power
source, if the current is in specification limit and you have some luck,
the board will work.
Daniel
Timothy Normand Miller wrote:
A relatively new professor here at OSU had one of these FPGA boards:
http://www.pender.ch/docs/GR-PCI-XC2V_product_sheet.pdf
Unfortunately, some students recently fried part of the power
regulation circuit. We don't have the expertise to repair it
ourselves, and we don't have the budget to buy something new. This
board was being shared by multiple students, one of whom was using it
for his masters thesis work. So its loss is rather painful and
problematic.
I was wondering if anyone could advise us on repairing this. Perhaps
there is someone whom we could ask to repair it for us? Trying to get
the original manufacturer to repair it would probably cost more than
it's worth. The damage was done to at least the C12 and D9 components
(lower left in the picture).
Any suggestions and help would be most appreciated!
_______________________________________________
Open-graphics mailing list
[email protected]
http://lists.duskglow.com/mailman/listinfo/open-graphics
List service provided by Duskglow Consulting, LLC (www.duskglow.com)
