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RIP: Asus responds to its flaming motherboard

Posted on 18th Mar 2009 at 10:12 by Richard Swinburne with 7 comments

Asus has responded with a detailed report as to why its M3A-H/HDMI went up in flames and smoke. After publishing the first episode following the freshening smell of burnt electronics festered in our labs, Asus was keen to take the board back to Taiwan for further testing and let us know how it got on.

RIP: Asus responds to its flaming motherboard RIP: Asus responds to flaming motherboard

Here's its conclusion, with Asus' words and pictures (all we have done is tidy the English a little):

Customer feedback to the damaged M3A-H/HDMI was a burnt out MOSFET.

Detailed information on the cause is in the statement below.

Backstory: The board was running fine with an FX62 for 9 months, then they dropped in a 9600 Phenom B2, without removing the motherboard or changing any other hardware and it firstly killed the Enermax PSU, they then replaced the PSU and the motherboard ignited within about 10 seconds.

Analysis:
1.Check the impedance of MOSFET Rgs. The test result is below. The normal Rgs is around 8K OHM and there is just VDD_NB high side MOSFET damage.

  Phase 1 phase2 phase3 phase4 phase VDD_NB
High side Rgs (OHM) 8.16K 8.28K 8.2K 8.07K 12.7
Low side Rgs (OHM) 8.22K 8.25K 8.25K 8.16K 8.15K

RIP: Asus responds to its flaming motherboard RIP: Asus responds to flaming motherboard RIP: Asus responds to its flaming motherboard RIP: Asus responds to flaming motherboard

2. Then we removed the VDD_NB high side MOSFET and re-check the impedance of PCB Rgs. The result is 8.05K OHM. This tells us that just MOSFET is damaged and the Driver function is OK.

RIP: Asus responds to its flaming motherboard RIP: Asus responds to flaming motherboard

3. Next we changed the MOSFET with good one and turn on the system. Then we checked the MOSFET gate waveform. According to the waveform all the function of VRM is still good.

RIP: Asus responds to its flaming motherboard RIP: Asus responds to flaming motherboard

CH1:VDD_NB High side gate
CH2:VDD_NB Low side gate
CH3:VDD_NB Phase node
RIP: Asus responds to its flaming motherboard RIP: Asus responds to flaming motherboard

RIP: Asus responds to its flaming motherboard RIP: Asus responds to flaming motherboard
VID=1V DC Load 0A

RIP: Asus responds to its flaming motherboard RIP: Asus responds to flaming motherboard

RIP: Asus responds to its flaming motherboard RIP: Asus responds to flaming motherboard
VID=1V DC Load 20A

Conclusion:
There is just VDD_NB high side MOSFET damage and it maybe caused by an abornal voltage or current spike. To determine the root cause we need the failed MOSFETanalysis report to help us find out. We have passed the failed part to vendor to do analysis so after receive the report we will update you again.

7 Comments

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Krikkit 18th March 2009, 10:19 Quote
Awesome. DSO's really are too cool for school.
DougEdey 18th March 2009, 10:22 Quote
They're going through a lot of effort for you, they must think highly of your opinions. Now get them to sort their support site and download servers!
Mister_X 18th March 2009, 15:36 Quote
Quote:
Originally Posted by DougEdey
They're going through a lot of effort for you, they must think highly of your opinions. Now get them to sort their support site and download servers!

Seconded, site and downloads are atrocious from ASUS
Zurechial 18th March 2009, 16:16 Quote
Quote:
Originally Posted by DougEdey
They're going through a lot of effort for you, they must think highly of your opinions. Now get them to sort their support site and download servers!

Third-ed.
Great hardware, but horrible support.
New Xonar D1 Firmware please!

It's quite interesting to see the kind of checks they're doing on the board.
For most enthusiasts, once you see a part of the board melted or burnt-out, the initial reaction is to treat the whole board as being fried.

For someone who knows their electronics that'd seem kinda silly, but seeing ASUS describe the result as :
Quote:
Conclusion:
There is just VDD_NB high side MOSFET damage and it maybe caused by an abornal voltage or current spike.
- Changes that perception of the board a little from the point of view of a layman-enthusiast.
Makes me wish I had the tools and know-how to test and repair components like this myself instead of going through RMAs. :p
jhanlon303 18th March 2009, 23:49 Quote
The problem with this whole scenario is $$.
Let's take a hypothetical tour
The board comes back to the manufacturer for RMA.
Without the association of Bit-Tech name you just throw it in a recycle pile.
BUT this one is high visiblity so we send it to "the lab".
Now these are not minimum wage individuals - these are highly schooled and trained people with a bazillion $ worth of state of the art equipment.

One 8 hour day for this engineer is probably in the $50 to $100 per hour so you have $400 to $800 invested in one day testing this board by the engineer. That assumes only one engineer. In my experience it is seldom 1 engineer doing the testing.

It is so difficult to spend the $$ to test that it is no longer economically feasible for a manu. to test hardly any of the RMAs.

In a perfect world a chain of RMAs for a device with the same defect should alert the people that they have a problem with component XX. But it seldom happens.

I don't know what the internal cost of this board was to Asus but it was probably less than a good evening meal out.

One can only hope that by this exercise Asus will improve either the component or the design.

It's sad to see so many $$ parts scrapped out because of one 4 cent part.

I do hardware and software for a living and have for 30 years.
Pulling a card and replacing it is cheaper than fixing.

john
Krikkit 19th March 2009, 11:00 Quote
I suppose the level of service would depend on whether the tech people are really concerned about it - if it was just a silly bugger of a pre-release board, I could understand them not making a big deal, but once something actually goes up in flames it certainly warrants investigation.

I would bet that most RMA's don't involve fire, only a defective flash or similar.
Jhonbus 19th March 2009, 20:37 Quote
Lovely fingernails for an engineer.
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