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crystailrain2010
Observer
Observer
12,214 Views
Registered: ‎04-01-2014

Repair my KC705 board

Hi, guys, I need your help!

 

I  bought three KC705 boards, and two broken with the same reason, through i don't know  what the reason is.  Because I bought  them last October, they are now out of warranty period.  Now i want to find why  those boards broken.

 

Two boards suddenly power down when i was programing FPGA  in SDK(Xilinx tool----Program FPGA).  One power down during the programing process, when the progress bar went to 50%.  The other one power down after i programmed FPGA successfully.  Then the board can't power up any more.  

 

But before that ,the boards can work properly , I programmed  FPGA, then they worked the way i configured.   

 

I measured the entire board, found two places short out:  short between Vcc12_P and GND   ,short between  VCCINT and GND.     The other part is good.

 

 

1) Two times, when the board suddenly broken ,I was programming FPGA in SDK. And  in my ise project, i add a microblaze.   Microblaze's  is powered by  VCCINT.  VCCINT and GND short out.

 

 

2) I found in the forum someone's FPGA crashed beacuse of  heavy load .  http://forums.xilinx.com/xlnx/board/crawl_message?board.id=XLNXBRD&message.id=7678

 

so, I guess after i programing FPGA in SDK, because of the microblaze , the power consumption is too big, then the current  flow from FPGA to VCCINT is too heavy.   Then, by some reason i don't know yet, the VCCINT and GND short out,  then Vcc12_P and GND short out.    So my board can't power up. 

 

If my guess is wrong, i can't find other reason the board broken weirdly .  Can you guys help me to analyze the phenomenon?   Thanks in advance !

 

attachment is the key circuit of VCCINT, I also think it is  the key reason of  my borad's fault.

 

Best wishes

kc705.bmp
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6 Replies
crystailrain2010
Observer
Observer
12,193 Views
Registered: ‎04-01-2014

Is there anyone give me some advice?  Thanks!

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crystailrain2010
Observer
Observer
12,187 Views
Registered: ‎04-01-2014

Hi, I have another question.  I asked the TI's engineer, they said  if the PTD08A020W(u21)'s Vo(VCCINT) and GND short out, the PTD08A020W must be broken.   They suggest to change a new PTD08A020W and find why Vo and GND short out.  

When i want to change the u21 module,  I can't melt the soldering on circuit board. I am using  normal  soldering iron and it's  highest temperature is  450℃.     Can Xilinx engineer tell me  the soldering's  melting point?

 

Best Regard

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mcgett
Xilinx Employee
Xilinx Employee
12,180 Views
Registered: ‎01-03-2008

The ML605 board use lead free solder that has a typical melting point of 217-221C.

------Have you tried typing your question into Google? If not you should before posting.
Too many results? Try adding site:www.xilinx.com
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crystailrain2010
Observer
Observer
12,155 Views
Registered: ‎04-01-2014

Thanks for your reply.    

I tried to use the 450℃  -soldering iron, but i still can't melt the solder on KC705 board.  why?  

Can you give me some advice, Thanks!

 

 

 

 

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memset
Contributor
Contributor
12,149 Views
Registered: ‎12-23-2009


@crystailrain2010 wrote:

 

I measured the entire board, found two places short out:  short between Vcc12_P and GND   ,short between  VCCINT and GND.     The other part is good.

Best wishes


Hello! VCCINT short to GND and VCC12 short to GND is very bad.

Are you sure your VCCINT to GND is exactly 0.0 Ohm? If its like 1.0-10.0 Ohm, thats not a short.

If both VCCINT and VCC12 to GND are short (0.0 Ohm), that means your VCCINT power source is dead (output MOSFET is open-short). Usually, that means your FPGA got 12V on VCCINT and is now dead. If the damage would be limited to power block, you'll be VERY lucky.

 

To desolder a power brick you'll need some smart soldering tools like bottom preheat system or an hot-air or even a IR soldering machine. Another option is to use several soldering irons with a lots of Sn/Pb solder to flood the brick with the molten solder.

 

You can run a quick check on the damage done to the board by providing low voltage power like 0.5-0.9 V / 10-50A from a lab power source to broken board's 12V power and obvserve heating components (remove FPGA hetsink prior to test). If 0.5V lab PSU would be powering the board with all the allowed current (tens Amps) AND your FPGA gets really HOT - there would be no use in desoldering power brick...

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crystailrain2010
Observer
Observer
12,130 Views
Registered: ‎04-01-2014

Thanks for your suggestion!!   I will try to test the Kc705 board,post my result later.

 

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