Beware - Fake MCM6810 SRAMs...

[+Nezgar]

Well, I'll openly declare I've been burned... Back in April 2020 (and received in June) I acquired a batch of 40 6810's for my assembled US Doubler 1050 PCB's, enough to last me well into the future or so I thought...  I tested a few out today as I came to the end of my last set and these didn't work in the 1050... Then I went through testing each one. Every. Single. One. Doesn't Work. 

 

Had pretty good luck with EPROMS from China - a few duds here and there, some definitely relabelled but were just another brand of EPROM that I was able to figure out using the chips internal ID - but this acquisition stings because it's now well outside of any ebay buyer protection due to my lack of time and attention so late afterwards. ?‍♂️

 

So first rule of eBay buying NOS chips - test them within the claims window...

Second rule of thumb - Maybe buy a few from a seller first before committing to a larger batch.

 

There's really nothing in the datasheets that suggests there's a version of the 6810 that would be incompatible. The slowest one works with 1Mhz, which is what the 1050 runs at. The "P" in MCM6810P just means plastic.

 

Date code 1901... 6810 128 byte SRAMS made in Jan 2019??? yeah right!

 

Having seen a few videos about the Chinese counterfeit operations, These chips don't have 'painted on' tops - there isn't anything that cleans away with isopropyl alcohol, and the imprints are laser-etched - a "higher quality" fake. All 40 chips have exactly the same code underneath, which is uncommon for buying old chips. Some of the depressed/imprinted circles on the left/right of the label have varying depths, with some of them missing entirely - which I think is the most telling evidence that a few MM has been sanded off the top of each of the chips to facilitate the relabelling... The pins do not appear to be re-tinned.

 

This will put a pause on some 6810 doubler kits going out for a bit while I source a new (working) batch. ?

 

 

Now I wonder WTH these really are.... Some enlightenment from YouTube:

 

[Faicuai]

This SHOULD NOT have happened to you, to begin with.

 

The Chinese counterfeit operations go to unimaginable lengths... Even 50-pin EDGE connectors I bought no long ago are all pure garbage... Tested.

 

It is time we all stop being the fools on the other side of the rope. It is also clear that their inherent intent for deceit and theft at every possible corner will certainly NOT stop. 

 

Let's look for stuff made in other parts of ASIA, Latam, or even US/Europe, even if more expensive.

[TGB1718]

1 hour ago, Faicuai said:

Let's look for stuff made in other parts of ASIA, Latam, or even US/Europe, even if more expensive.

I'm in the UK and always select UK only, I know that Chinese sellers will use UK addresses to make it look legit,

the giveaway is the delivery time, real UK dealers will generally deliver within a couple of days, these "fake" UK

sellers have 2 week+ , now why would in-stock items in the UK take that long (even with 2nd class post).

 

I got taken once, I ordered an Audio to USB interface cable, when it came, I tried it, didn't work, so I checked

the cable with a meter, all it was, was a USB connector wired directly to a stereo phono jack on the other end, 

there were no converter chips in the USB end as advertised. 

I was lucky the 5V into a stereo didn't kill something (probably decoupled by capacitors), I contacted the seller

telling him he was selling duff, dangerous, cables and was going to inform eBay, I promptly got a refund and

his advert on eBay disappeared

 

[+kheller2]

GRRR... I have a batch I'm going to have to check now.

[ivop]

10 hours ago, Nezgar said:

Maybe buy a few from a seller first before committing to a larger batch.

That's very good advise. In the past, when I started a new project and needed a certain chip, I always ordered two or three of them from different ebay/aliexpress vendors. I also did that because one of them might not arrive. Or if it's defective, you have to wait another 2-4 weeks, etc...   But in the end, I have several ICs in two- or threefold, all working But it's good practice at first.

 

Really sorry to hear that you got ripped for a batch of 40 pieces ?

Edited January 18, 2021 by ivop

[BillC]

6810P are available from Jameco for US$4.95ea. They also have discounted prices at varying purchase levels. US$3.95ea. @50+

While more expensive than eBay/Aliexpress it is very unlikely that Jameco would be selling counterfeit chips.

https://www.jameco.com/z/6810-Major-Brands-IC-6810-SRAM-1024-Bit-128x8-450ns-1MHz-5V_43561.html