I have been using NI PCI-6503 as digital IO card for more than 3 years. I have been using them without any problem along this time. I use the pin 49-50 to power up a pullup with 5v. Recently, I have bought another set of these cards but for my surprise, there is no 5v on those pins. Visually, some differences can be seen between the old and the new cards. I write you down the serial numbers of the cards...
BAR CODE: 13B204E
BOARD-CODE: 185185B-01 UL94V-0
CHIP: NI mM1TE1-A JAPAN
5v FUSE: 125F ODKZ
CHIP: NI mM1 TE1-A KOREA
5v FUSE: LF T (2A) ====> IT HAS CHANGED! (At the same time of writting, I have noticed there is no continuity in the fuse...)
I have shorted the fuse and now, 5v are OK!
Can this be dangerous? For the PC? For the device connected?
Are all of the cards with this new fuse with the same problem?
serial numbers (13B204E, 14C45A5) identify your boards and part numbers (185185B-01, 185185C-01) identify the type of board. The letter means the particular revision of them, so, C is more modern than B. This has nothing to do with functionality, which is the same, but the components themselves may have changed. So, revision C board must supply 5V between 49 and 50 pins and if not, the board is damaged.
As you say, the fuse is not working. During revisions of several of our boards, we replaced a self resetting fuse to a one-shot slo-blo. This fuse will be labeled F1. It is clear that the fuse has been blown. I strongly recommend NOT to shorcircuit the fuse because the board, the PC or yourself can be seriously injured.
If you are spanish, please phone me at 91 640 47 64 (NI Spain, Jesús Garrido) and I will help you to repair the board (RMA). If you purchased recently this board, you won't have to expend any money on it because boards have a warranty period.
I wait for your phone call!