Howdy,
I'm working on a research project at Texas A&M University and we're using LabView and USB-6008/6051 hardware extensively for the prototype's control systems. We've run into a slight problem, namely the digital +5V rail of our USB-6008 seems to have been fried by a separate board that was connected to it. Figuring I've already voided whatever warranty I had, I've taken a look inside to see if there's a part I could replace.
My best guess is that the part that might be labeled CR21 on the PCB is no more. I say might because the silkscreen is cut off at the edge of the board. It's the black surface mount component that says something like "E ? SO" in the corner of the board near pin 32. The magic smoke came out through a small hole where the middle digit used to be, but the component next to it that looks otherwise identical says "E 2 SO". As best I can tell, it looks like it was formerly a zener diode for voltage protection, but it's now enjoying life as a 1-ohm "resistor". This is unfortunate as it nearly shorts the neighboring regulator's (looks like TI REG102GA-A or equivalent) Vout (which seems to power the +5V rail) to ground. The data sheet I found for the regulator claims indefinite short-circuit protection, so there's a chance it's OK unless the junction temperature got high enough to bake it, but it seems easy enough to replace if it's kaput. The remaining problem is that I can't seem to figure out what to replace the former diode with since the markings aren't distinctive enough for a productive search. If the markings mean anything, we haven't figured it out yet.
Since we don't have unlimited funds or time, we'd really appreciate it if anyone could suggest a replacement part or give some kind of specification. Alternately, I wonder, would it run without the diode? I'm not as sure about this, but I suspect the other diode (CR1) is redundant with the busted one. Even if it's not and it really is just for voltage protection, I can deal with not having it there. If this sort of information is off limits due to co. policy, trade secrets, or what not, just let me know and we'll just try to do without & find another way. (But if you can, you'll be our hero(es).)
Thanks in advance,
Andrew Echols
