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dmitrip
Visitor
Visitor
5,728 Views
Registered: ‎03-08-2011

fried ML402 power

Hi, everyone,

 

Our ML402 evaluation platform with Virtex-4 (5V power supply) was briefly plugged into a 19V power supply, and is probably fried, as the power light is flashing, indicating an overload condition.  There are three power regulators on the board, all of which are probably damaged. 

 

Any advice about repairs, or is it hopeless?

 

Thanks

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6 Replies
gszakacs
Professor
Professor
5,724 Views
Registered: ‎08-14-2007

Since probably no circuits on the board use the 5V input directly, it's likely that only

the power supplies themselves were damaged.  If you can replace them it's

probably worth a shot.

 

-- Gabor

-- Gabor
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eteam00
Instructor
Instructor
5,718 Views
Registered: ‎07-21-2009

There's quite a bit connected directly to the VCC5 input rail on the ML40x board schematics.

  • Keyboard + mouse ports (hopefully with neither connected at the time)
  • FETs Q1 and Q2, which hopefully didn't suffer reverse bias breakdown and fry some FPGA pins
  • numerous 0.1uF - 1uF caps which were hopefully rated for at least 12V (if not 25V or 50V)
  • U39 Bus buffer SN74CBTD3384 (connected to the FPGA)
  • U15 LCD
  • U?? Audio Codec LM4550
  • U44  USB 5V power switch Micrel MIC2525-2B
  • U32 Power Supply TPS54610PWP for 1.2V
  • U30 Power Supply TPS54310PWP for 3.3V
  • U31 Power Supply TPS54310PWP for 2.5V
  • U33 DDR VTT Power Supply TPS51100 (linear)
  • U35 Linear regulator TPS73118 for 1.8V
  • C45 2200uF electrolytic
  • DS18 green LED

I would suggest connecting a bench power supply to the 5V input connector, slowly dialing up the current limit control from 0 (current limit) to around 3A or so.  See if the supply voltage will run up to 5V, or if current limit holds the output voltage to some lower level.

 

If the supply stays current limited (at 3A) below 5V output, the odds are good that some device(s) (including decoupling caps which may not be rated for 19V) has shorted to GND.  Any such shorted devices should be getting warm -- VERY warm.  Using the 'hot thumb' test (or the rising plume of smoke test), one by one remove the shorted items from the board.

 

With all the shorted items discovered and removed, what will be left are:

  • undamaged items
  • open circuit fried items
  • unfried items with partial damage

You will simply have to work through the board, one component at a time.

 

If your time has some value (greater than zero), or you cannot afford to invest further development effort with a suspect compromised board, then this is your chance to

  • donate the old board to a school (for a charitable donation and tax deduction, if in the USA)
  • upgrade to a more current (and more powerful) development platform

Hope this helps...

 

-- Bob Elkind

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robinliuy
Voyager
Voyager
5,706 Views
Registered: ‎05-21-2008

Besides power silicon, coupling capacitor and inductance should be also checked.
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dmitrip
Visitor
Visitor
5,661 Views
Registered: ‎03-08-2011

Thanks very much.  I will run through the suggested tests and hope that not many components are at fault.  Otherwise it looks like it's time for an upgrade...

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Anonymous
Not applicable
5,650 Views

Since the board failure is due to wrong power. So I am sorry to say that there is no possibility to get board replacement from XILINX.

 

If regulators failed immediately after wrong power you are lucky. Because they will acts as bowled fuses and protect remaining part of the circuit.  

 

The below are some suggested steps to debug your board

  1. Remove failed regulators and measure DC resistance between power rails. If they are not dead shot then there is less possibility of other components failure.
  2. If dead shot is there then it is unlucky. There is possibility of other components failure. Then it is little tough to debug. One way is find out where the resistance is low and replace that nearest component.
  3. Find out the failed components by binary replacement method

 

Some third party servicing stations might available locally. If the Power adapter is not same which is supplied with Board it is always safe to measure voltage before connecting to the board.

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eteam00
Instructor
Instructor
5,649 Views
Registered: ‎07-21-2009

If the Power adapter is not same which is supplied with Board it is always safe to measure voltage before connecting to the board.

Now you tell him!

 

-- Bob Elkind

SIGNATURE:
README for newbies is here: http://forums.xilinx.com/t5/New-Users-Forum/README-first-Help-for-new-users/td-p/219369

Summary:
1. Read the manual or user guide. Have you read the manual? Can you find the manual?
2. Search the forums (and search the web) for similar topics.
3. Do not post the same question on multiple forums.
4. Do not post a new topic or question on someone else's thread, start a new thread!
5. Students: Copying code is not the same as learning to design.
6 "It does not work" is not a question which can be answered. Provide useful details (with webpage, datasheet links, please).
7. You are not charged extra fees for comments in your code.
8. I am not paid for forum posts. If I write a good post, then I have been good for nothing.
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