PCI-MIO-16E-4 Failure (Burned Part) Why?

[BryanSw]

Now it was depressing enough to turn on my computer and see that may Daq card was not working. It was more depressing to see why it wasn't working any more.

Upon visual inspection of the PCI-MIO-16E-4 (PCI-6040E) I found a small surface mount Mosfet on the board had completely fried. On day the card was working great next day it was failing both AI and AO functions. Digital I/O appears the only thing that still works. I have ran the NI Diagnostic utility to confirm this.

Now back to the burned up part. Seeing it would probably cost nearly half the price of a new board to have it repaired I decided I would try to figure out why it  fried (the small Mosfet).

On the card there is a differential choke near the PCI card edge connector. It is labled as "EXL 154 100". From what I can tell the PC's +5v enters into the card and passes through this choke before making it's way to other circuits.  But right after the choke is a Mosfet. This Mosfet has the +5 v from the choke going to it's drain, it's source lead is tied to ground. The gate connects to the ACT02 "Quad 2 input NOR gate". Of course the are much more components but the concern it why in the world would someone put a Mosfet from the main +5v entering the card to have it purposely short to ground via (drain to source). What is the purpose of this?

This type of circuit is on another card also I have looked at  (an AO card from NI). I can't help thinking it was designed to do just what it did burn up, after a certain period of time or use. Hope someone can expain this in some detail. I've been looking at this board from a week now trying to figure out why it burned up and I can't find anything else that could explain it.

Bryan

[ChrisR. · Accepted solution]

It is not designed to self-destruct!

It is a boost converter: http://en.wikipedia.org/wiki/Boost_converter

[Teledyne]

Hello Bryan,

Did you ever find the solution to this problem?

Did you manage to fix your card?

I have a PCI-6111 that has failed in the exact same fashion.

I guessed it was probably a power converter, but I susect it may be using a transformer rather than just a inductor (I need to do more fault finding).

I swapped the FET out and got lots of magic smoke! So I suspect something else is a short to ground.....

Your experience would be much appreciated.

Alex

[johnsold]

Alex,

BrianSw has not logged in to the Forum since 2012, so he is unlikely to answer.

Sorry, I have no suggestions about the magic smoke.

Lynn

[BryanSw]

I'm still here. Yes, I was able to repair my card. As mentioned in a response to my post some said the circuit in which the mosfet failed was a buck boost circuit. After reverse engineering the circuit I can confirm it was a buck boost circuit. Now, what caused it to fail was a shorted decoupling capacitor, which in turn damaged a 15 vdc regulator, and finally the mosfet in the boost circuit. The boost circuit takes 5vdc from the computer's pci buss and converts it to a higher voltage to drive the the 15 vdc regulator. The decoupling capacitor was on that 15vdc line to otger circuits. It burned up also. So, I replaced the cap, 15 vdc regulator and the mosfet and the board works now. The mosfet had an smd code marking of 355 if your interested. You will have to look up what device is used from that code. I can't remember the part number. I you need it I will look it up for you. Look for a burned or discolored capacitor. Mine was completely burned up so it was easy to find. Replace with a suitable one. You could have had some other part fail but mine was a bad capacitor that started the whole thing.

Good luck,

Bryan

[Teledyne]

Hello Bryan,

Thank you for taking the time to reply in detail.

This will help a great deal in debugging the fault.

Once I have found a solution I'll post it online for the benefit of others.

Best regards,

Alex

[NEWKlear]

Just to give some NI input,

We always recommend going through the official NI RMA process(except for replacing relays on switch boards).

When performing a self repair NI does not guarantee that accuracy or calibration is within specification and the full verification and validation test process is not performed on the card.

Also, for thermal events(burnt components, etc.), NI likes to keep track just in case we see any trends so we can take action to better improve the experience for our users.

Specifically in this case, it is very likely, given the damaged component, that the calibration of your board is not functioning properly.  

On the other hand tearing apart hardware and making it work again is our job duty as engineers.  So I can completely understand the method and appeal in this situation.

Best Regards,

[BryanSw]

I understand your concern in the matter of repairing your boards. The board I repaired was purchased on Ebay at a very reasonable price. In fact I purchased 2 of them so I could have a back up. I used the NI diagnostic to check for proper operation of the boards. These boards were used at home for hobby work and was not used for any critical measurements. They do appear to work fine and are as accurate as I need them to be. The PCI-MIO-16E-4 is a fairly old data acquisition card. At it's age I expect that it could develope a component failure at any time. It would have not been cost effective for me to have it sent in to NI for repair and calibration. People that purchase Data Acquisition cards  through NI, and are able to pay full retail value should have them returned for service and calibration especially if they are used for critical measurements such as in a medical field for instance. I've been using NI equipment and software at both my current and previous places of employment. We regularly send out NI equipment to NI for both repair and calibration.

[reichenbach]

http://www.artisantg.com/TestMeasurement/59238/National_Instruments_PCI_MIO_16E_4_PCI_6040E_12_Bit_M...

These guys sell used, fully warrantied NI equipment. They also do repair on NI: http://www.artisantg.com/RepairNI.aspx

Thought that you'd like to know.