I'm struggling a bit with diagnosing a defective Labjack U6. I'll provide as much (visual) info as possible, and hopefully I'll be able to resolve the issue.
So, here goes...
During a schoolproject I've encountered a defective Labjack U6, which previously was used in an engine dynamometer. Even though I'm normally not active in this area of expertise, it is pretty essential to search for the cause of the defects, because we were lucky enough to receive a spare U6.
We're now working with our last and only U6, so we want to make sure it doesn't blow out immediately or during runtime when hooking it up to the engine dynamometer again.
Because that's what had happened to the previous one. We already discoverd that the Labjack was dealing with a lack of voltage (1,17V between VS and GND). PC's couldn't recognize the device, and none of the status LED's lit up during connection. After opening the case three (clearly) blown out chips were visible, marked as; U6, U16 and U21.
With help from the functioning U6 I was able to read off the markings from those three chips.
U6: D752 TI83 Z54W
U16 is described here in an other topic as a control chip, and that should not be relevant to the other two chips blowing out, would it ?
U21 I guess would be a '8X' mulitplexer ?
U6 I found after extensive search to be a 12-bit digital to analog converter, by Texas Intruments. I've attached the datasheet. Did I get this right, or have I found the wrong part ?
IN the U6 chip's case, the entire left side seems to be blown out. The side which seems to handle the analog input and output voltages from DAC_A and DAC_B according to the pin description in the datasheet.
Finally we come to the point where I'm at now, stuck. I'm trying to connect these blowouts with the ports of the Labjack. For use with the dynamometer we have signals like RPM, temperature, load cell. All in all we're tryin to figure out if any of these signals could have caused too much of a voltage on those chips and caused them to blow out.
Again this is all done as an important precaution. We can't afford to risk 'lighting up' our second Labjack as well.
I'd appreciate any help, suggestions, ideas whatsoever. If there is need of further clarifying things, I'll be glad to explain.