Hello all. I was walking around the manufacturing floor today and saw a component catch on a fire on an assembly fixture. The test engineer ran frantically over to it to try to fix it. Turns out it was an old fixture and no one documented parts on it.
I want to try to help him out and find out what component it is. None of us know what it could have been. Anyone seen anything like it?
Could be a transformer of some kind.
Could be an optocoupler device.
Definitely it is NFG (not functioning good).
It's quite clearly a current shunt (4-terminal resistor)
It says directly on the sticker over it what it's resistance should be (calculated from the 0.xxxxxV @ 5A current)
// Per.
Do you mean the white sticker? Sticker says 5V / 0 - 300VDC. I was thinking a choke maybe. This is what the test engineer drew out for everyone.
Lesson for anyone that makes fixtures or other tools in a company, create documentation for the future!
I think you need to trace out more of the circuit to figure out what it was. I have never seen any part that looked like that - and it looks old as the hills, ie, they probably look different now. Though - it does look like it could be a 4-terminal resistor (though what value?!) Can you make out any markings on the burned part?
Also, are you sure those things on the right that it looks like it's connected to are resistors as shown in your drawing? They look like they could be tantalum caps to me?
The circuit with two 1 meg resistors next to two parallel 18k resistors, with no connection in the middle, doesn't look normal.
What are the wires on it going to?
@Zapro was confident about it being a current shunt. I had my doubts, but the component that I could find that looks the closest to it is this: 4 Watt Wire Wound 4-Terminal Axial Precision Resistor, Kelvin Shunt. With those resistors around it, it must be a high-side current shunt. Did a capacitor shortcut ?
@ Zapro Looking at what Koepel linked, it does look pretty similar. This is the closest looking part to what the test engineer has searched.
@ Koepel Thanks for linking that!
@ larryD It definitely is NFG.
@ DrAzzy The thing is so charred it is impossible to tell.
To all, thanks for the reply! The test engineer appreciate it and is currently still working through the rat's nest of wires in the fixture. I suggested to him to look at the automated code in the fixture, but his luck is really bad. Mostly everything here is written in labview, but this is written in some weird program called softwire. No one employed here can program in that!
Thanks again.
I would measure resistance across terminals on that part. That way, you know what values to look for in replacement part if it's still working somehow.
Wirewound resistors can be insanely durable. My father has seen high quality wirewound power resistors that could get so hot that the glaze started melting off, and still work fine afterwards.
Koepel:
the component that I could find that looks the closest to it is this: 4-Terminal-Resistor
Yeh, I'd agree with that - precision current sensing.
Yours,
TonyWilk
P.S. Too much current by the looks of it 
Wirewound resistors can be insanely durable. My father has seen high quality wirewound power resistors that could get so hot that the glaze started melting off, and still work fine afterwards.
Yes they are, but it also begs the question of 'why' it roasted. What other component failed?
