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I'm wondering if anyone can help ID the component in the red box as well as the IC right next to it. I suspect that they are a diode (the tapered end might indicate polarity?) and some kind of Opamp respectively. This board is pretty old. It came out of an aircraft radio for a Cessna 150.

I tried googling "National Semiconductor JR56AB" and other variants for the IC but absolutely nothing came out of it.

I haven't physically seen the board yet. My friend just sent me the photo. Otherwise I would be doing some DMM tests on it.


enter image description here

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The "JR56AB" looks like a lot code to me. I wonder if it's a 100k series part... – Ignacio Vazquez-Abrams Feb 15 '14 at 5:40
Everything I'm finding points back to the LM431. – Matt Young Feb 15 '14 at 5:47
@IgnacioVazquez-Abrams I think you're right about the code. My searches for "100055" is bringing up aviation results so we may be on the right track... – superkittens Feb 15 '14 at 5:50
I have never seen a 100k series part in a DIP package. The first LCCs (ceramic) I saw (in 1982) were 100k. 10k, sure, they were available in DIP (though not plastic that I ever saw). Plus the PCB doesn't look like a high speed digital layout, so I suspect you have to keep looking... – Brian Drummond Feb 15 '14 at 11:19
up vote 2 down vote accepted

That's a tantalum capacitor. It's a fairly common package. Check the markings in person, but the Kemet would be my first guess as the manufacturer.

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You're right. I just checked Digikey and that package is popular – superkittens Feb 15 '14 at 5:55
@superkittens Still need to figure out what this IC is, how old is this board? – Matt Young Feb 15 '14 at 5:56
I believe the board was made around the late 70s to the 80s. – superkittens Feb 15 '14 at 6:02
@superkittens At that age, I would bet money we are dealing with an obsolete part. TI has been very good about keeping National's documentation up to date and available. I'm not finding any reference to the lot number or part in any of the documentation. – Matt Young Feb 15 '14 at 6:05
Yeah it's probably an obsolete part. I guess I could try contacting TI directly or if I could, decap that sucker! If only I had the means... – superkittens Feb 15 '14 at 6:12

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