Fake Dallas DS1486 has just one battery -- photos included

[rodd]

I bought a couple of DS1486 to practice my Dremel skills so I could use them on the "real one" installed on MY TDS784D.
I have seen some photos of the real chip carved to expose the batteries and there were two of them.
To my surprise the "new fake" one has just one.
I have attached the photos here for reference.
If that is the new "state of the art" it will be easier to confirm that the chip is fake probing it with a strong magnet.
Roger

[youngwug]

Is the one shown above positive(+)?
Does it stick to pin 1?

[rodd]

I lifted the battery now. The positive is on the bottom.
I could not find continuity to any of the pins to the battery, but when I carved a little bit more to try to find the connection to the pins this green stuff appeared.
Corrosion?
I have attached two more photos
The positive terminal of the battery goes to the greenish part of the left of the photo

[james_s]

I opened up a fake Dallas chip, I forget exactly which it was but I found that same looking yellow wrapped battery. I started xraying Dallas chips and found that the fakes are easy to spot. Of all the ones I've bought from China a few were genuine but old used parts that had been sanded off, blacktopped and printed with new labels, one of those even had data on it already, or counterfeit parts that are completely different. Not a single one of the counterfeit parts worked correctly though not all had the same problem.

[fzabkar]

This might be a better solution:

https://www.eevblog.com/forum/repair/dallas-ds1486-and-ds1250-replacement-designs/

[Berni]

This might be a better solution:

https://www.eevblog.com/forum/repair/dallas-ds1486-and-ds1250-replacement-designs/

I made made Dallas NVRAM replacements using Cypress FRAM chips with parallel interfaces. You get 100 year data retention with no battery to go bad.

Running them in a HP 3458A just fine.

[james_s]

This might be a better solution:

https://www.eevblog.com/forum/repair/dallas-ds1486-and-ds1250-replacement-designs/

I made made Dallas NVRAM replacements using Cypress FRAM chips with parallel interfaces. You get 100 year data retention with no battery to go bad.

Running them in a HP 3458A just fine.

I did that too but it didn't work in a Tektronix power supply. The basic functionality worked fine but there was part of the calibration routine that would fail every time. I believe it has to do with a quirk of these FRAM chips in the way the address is latched, you have to de-assert the CS input between each address, or something like that. You are dependent on how the firmware in the device you're trying to retrofit was written in whether it will work or not.