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Identify this diode.

Stamey

Apr 28, 2023
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I have a 12v automotive battery tester that has died. It is a "BT200" model from China. I am looking for this diode, which seems to be bad, but am unsure of how to identify it to get a spec sheet or replacement for it. It is D2 in the pic. It only measures about 3mm x 1.5mm, so it's quite small.

Thanks,
Chris
 

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danadak

Feb 19, 2021
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Could be a diode, a zener.....

If you hand draw a schematic it might be possible to figure out its purpose.


Regards, Dana.
 

Stamey

Apr 28, 2023
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I think it was open, but I didn't determine it. My mentor was going through the circuit and told me to try to find these diodes. You can see in the pic, a diode that has been replaced with a through-hole diode that he was guessing about, and that diode did get the unit to light up for a few seconds, but he theorizes that it isn't correct and tasked me with finding what is supposed to be there. This kind gentleman got out of the business some years ago and is retired now, therefore is not familiar with some of the newer packaging of components, I suppose, so I got the job of finding the component.
From the web sites I have looked at, it seems like I should be looking for two stripes on the diode. In this pic, I can only make out one, either gray or black, and the other may be green, but I need to examine it again (It's over at his shop right now).

Thanks,
Chris
 

Stamey

Apr 28, 2023
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More pics. In these, the stripe looks blue to me.
Is it a schotky, zener, etc?
 

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Bluejets

Oct 5, 2014
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One can test for standard diode or zener quite readily assuming the one you show is ok.
Test for schottky I'm not sure of but should be something on the web.
Easiest way is read the number if any .
 

Stamey

Apr 28, 2023
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That's my problem, there are no markings on it except for the stripe.

Thanks,
Chris
 

Bluejets

Oct 5, 2014
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Then you are out of your depth unless you know or can find videos on how to test for relevant devices.
 

kellys_eye

Jun 25, 2010
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Schottky diodes have a lower Vf than standard silicon devices (0.2V rather than 0.6V) so should show on a diode test meter assuming the diode is actually working.
 

Stamey

Apr 28, 2023
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You are correct. I am out of my depth. I am on a learning path and trying to educate myself with YouTube and other web sites, plus this kind, retired technician who lives near me.

Chris
 
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