5V power seems to have failed on PCI-6221

[Scott J]

I recently had a test fixture go down, and it seems like it might be related to the +5v supply. 

When I connect 5v to the fixture board using an external power supply, the board draws 50ma, far under the 1A I believe the PCI-6221 supply is specified to be able to supply.  When I connect the fixture board to the PCI-6221 through the cable, only 0.67v are measured on the board.  However, when the cable is not connected to the fixture board, I measure 4.5v on the 5v supply from the PCI-6221.

I couldn't find an accuracy specification for the 5v supply, but I would have expected it to be closer than 0.5v.  It seems like the supply of my PCI-6221 can output some voltage at open circuit, but quickly decreases under a load condition, which seems like the board has failed.

Ideas?  Thanks in advance.

[JoshY]

Hi Scott,

For analog out, the board specs say the voltage accuracy is roughly 3.2mV, so definitely less than .5V difference you’re seeing. Also the 1A that the board can supply is a max. There’s a fuse that limits the current to 1A to prevent damage to the hardware. Sounds like you've done some troubleshooting already, but just to make sure it’s actually a board failure, there are a few more things you can try.

You can try recalibrating your 6221 in MAX. Also, have you checked the cabling and other connections? For example, you can check the reading at the end of the cable when it’s connected to the 6221 but not the fixture board. Another possibility is that the power supply isn’t capable of sourcing enough power under load. However, if this turns out to be a board failure, you can call in to the service department (866-ASK-MYNI) and request an RMA.

[Steven_K. · Accepted solution]

Hi Scott,

The 5V terminal on the 6221 is the 5V rail of the PCI bus with some fusing, so the accuracy will depend on the computer's power supply. Would you be able to try this card in a machine that currently has a working DAQ card? This would help rule out any power issues related to that particular computer. If this test fails, it is likely that there is a blown fuse and you will need to contact us like Josh mentioned for an RMA.

[Scott J]

After posting I was reminded that a duplicate testing station existed, and so I can swap things out as is helpful.  

This morning I used the cable and fixture that were failing on the other computer and DAQ card and the fixture worked, so it seems it is either the DAQ card or the PCI power supply as you mentioned.  

Since the other PCI card and computer are working, I'd really rather not take out the working board and install the one giving me issues.  Would checking the 5v rail of the PCI bus on the failing computer/DAQ board give us similar information?  If so, I'd much rather do that.

Thanks

[JoshY]

Hi Scott,

Checking the 5V rail of the PCI bus on the failing computer could give similar information, but we kind of expect it to fail at this point. Unfortunately, the best suggestion is what Steven said- to check the card on a machine with a working DAQ card. It's definitely more trouble, but it will provide the best information.

[Scott J]

I tested the problematic board in the working computer and still had the same results as with the other computer.  I then reinstalled the working board and the fixture again worked great, so I think there is a board issue.  I'll call in for an RMA.  Thanks