Electronics > Repair

What methods do you use to test LM239 comparators?

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2N3055:

--- Quote from: Postal2 on January 08, 2025, 07:19:35 pm ---
--- Quote from: schmitt trigger on January 08, 2025, 07:04:17 pm ---I also believe that something is becoming lost in the translation. You cannot bend a DIP or SOIC package, it will crack long before it actually bends.
Perhaps you meant something else?

--- End quote ---
No, I'm trying to find these chips in boxes now, I'll find them and take a photo. I can wrap them like hot chocolate. LM339, should be TI, but I don't remember exactly.

--- End quote ---

OK I think I understand now.

Plastic of the case behaves like thermoplastic, getting soft..
Yes if you have that, those are very fake chips.

I assure you that original chips  by any real factory is made from different material that will not behave like that.
Not only TI , but any real factory even from third world countries.

Zero999:
My go to is a Schmitt trigger oscillator. Here's an example of one I simulated, to test this simplest model I could come up with for an open collector comparator. The LED should flash at about 1Hz. You could build 4 to test your LM239.

Postal2:

--- Quote from: Zero999 on January 08, 2025, 08:39:23 pm ---My go to is a Schmitt trigger oscillator. Here's an example of one I simulated, to test this simplest model I could come up with for an open collector comparator. The LED should flash at about 1Hz. You could build 4 to test your LM239.

--- End quote ---
Yes, this looks very much like what is needed. Thank you. I would like to determine the leakage of 1 MOhm between arbitrary points of 4 comparators, I will try.

--- Quote from: 2N3055 on January 08, 2025, 08:22:27 pm ---OK I think I understand now. ...

--- End quote ---
I haven't found the chips themselves yet, but I did find a photo of me soldering the LM339. When I find the chips, the markings will be clearly visible.

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