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Comment by exmadscientist | Hacker News Reader

FYI, that is NOT what genuine Microchip DIP markings look like. Compare, for example, https://www.lcsc.com/product-detail/Analog-To-Digital-Conver... .

Also there is zero chance that some of them have bottom-marked lot codes and some don't, given the same top date/facility code. Dead zero. And the cavity IDs on the DIP molds should be the same style, not randomly mismatched.... I'll stop here, but this is classic gray market remarking stuff. These are random old chips that have been relabelled.

They may well still be AY-3-8910s in there -- the gray market is very creative -- and may well be usable for you, but be cautious. If they look like they're misbehaving, the chances are much higher than usual that it's not your fault.

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I really don't understand why chip resellers re-mark chips like this. It's always obvious and it gives me the idea that they have something to hide. I've paid more for obviously used chips that I can tell are genuine than "new"/"refurbished" examples like the ones in this article.

I love the AY-3-8910 and I've bought chips that were remarked in this fashion, fortunately they all worked ok and sound like the real deal.

There were such chips sold under the Microchip brand. I may still have one somewhere in a box.

Yeah it's strange, they've clearly been relabeled and maybe only the top two I tested are real. Even if that is true I still have a couple of new toys to play with. I'll test the rest tomorrow.

I finally got around to testing them all. It turns out that of the 2 I already picked off the top of the stack, one works perfectly and the other works mostly but is slightly intermittent.

The remaining 8 are all either dead or not AY chips at all.

I WAS WRONG: https://doug.lon.dev/blog/2024/fourays/chip-testing/

My testing was flawed, in fact all but one of the chips work. Pretty happy about that :)

can you explain what "cavity IDs on the DIP molds" means?

Things that are mass-produced in very high volumes by injection molding are never molded just one at a time: the molds have multiple cavities to make many parts at a time in a single molding shot. Very often, each cavity will have a marking to identify it: sometimes just a number, sometimes alphanumeric, sometimes dots. So you can tell that if everything coming out of cavity B12 is having quality problems, you probably need to inspect that cavity.

Now take a look at the picture in the article of the undersides of the DIP-40 parts. There are two circles, which are either ejector pin locations or just things that look like them. (Ejector pins are the things that kick finished parts out of the mold once they're done.) Inside a few of those circles you find those cavity markings. I'm not sure exactly why the ejector pins and cavity markings (appear to?) coincide, but it's pretty common out there in the wild. You'd need someone who's more of a mold specialist and less of an EE to answer that one.

I've looked at Lego bricks more than I care for and I've noticed similar mismatches over the many years that a particular brick was produced, but they were all still original Lego. It could simply be that at some point a completely new mold was made and it has its markings in a different spot.

There are also so called modular molds with interchangeable inserts.

Yes, mismatches over the years are completely normal... but not with the same date code and site code.

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