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Warning: faulty EPROMs on ebay, alieexpress, etc.

A

Apocalypse

Ok so long story short I was in need of a lot of 27C010 and 27C020 EPROMs and as I didn't need the chips quickly (I've been away from home for a month) I ordered them on ebay (27C010) and alieexpress (27C020).
They were 4 times cheaper than local stores (I know, this should have alerted me).

Meantime I've received the chips and I'm back home. First thing that intrigued me is that the chips have a rough surface instead of completely smooth (first time I see that).
For the 27C010, 75% are impossible to burn, 100% for the 27C020.
Of course I've tried everything I could (erase them, different speeds, different programmers, etc.) with no success.

To me the pattern I see is the rough surface, however it's nearly impossible to detect from sellers pictures (generic photos used).

You guys are warned.

P.S.: Anyone else had this problem before?
 
I had a similar experience with a bunch of 27c160's.

In fact, I got SEVERAL batches from several different sellers on eBay.

Maybe 50% were outright impossible to burn. The other 50% told me that they were the wrong chip (despite being labeled correctly), but burned okay anyway.

Same rough surface.
 
yantzlf is the only one still in my recent purchases.
 
and they are often reprinted, most in datacode.
you can make the real print visible with acetone................
 
Last edited:
Darksoft and I are dealing with a batch of shitty 27C080. Most will not erase. All of them complain about an incorrect device ID but even older ones I have for years do that with my TOPMAX2.
 
I have a very large amount of 27C1001/010 EPROMs I bought in an auction on eBay in Melbourne, almost all are NOS (there was a lot more but I split with a friend who collected it for me and posted up my half)

If you need any @Apocalypse - I can help, and I'll verify they're blank before I send :)

Sorry to hear about your bad experience :( I have bought many EPROMs (27C322 mostly but some 1024, 400 and 4002 and quite a few GAL16V8) and so far I've had 2 failures on the GALs and 1 bad 4mbit EPROM) from gc_supermarket on eBay
 
Apocalypse said:
P.S.: Anyone else had this problem before?
Click to expand...
Absolutely many have had this problem. In the past 2 years EPROM prices have almost tripled and some suppliers are no longer selling recycled chips. Only going to be more and more faulty/counterfeit eproms going forward.

Sellers are getting more creative with 'refurbishing' chips, got these last year:
20170523_103951.jpg

Typically for new designs that require small capacity 5volt chips, I will use SST39SFxxx Flash parts. Unfortunately they are not standard JEDEC pinout and are not backwards compatible.

After I got 100 of these repainted chips (approx 20% of them were faulty), decided no more buying used EPROMs.

So what are we supposed to do?!?!?!

https://www.digikey.com/products/en?keywords=AT27C

Start using OTP (one time programmable) non-erasable brand new off the shelf proms. They are available in 256/512/1024/4096/010/020/040/080 capacities/pinouts, and for a fair price imo
 
brizzo said:
Start using OTP (one time programmable) non-erasable brand new off the shelf proms. They are available in 256/512/1024/4096/010/020/040/080 capacities/pinouts, and for a fair price imo
Click to expand...
I'd love to start doing this as I rarely need to rewrite and I'd rather not worry about UV leakage corrupting my ROMs over time. Is there a good EPROM to OTP PROM part number cross reference somewhere?
 
brizzo said:
Apocalypse said:
P.S.: Anyone else had this problem before?
Click to expand...
Absolutely many have had this problem. In the past 2 years EPROM prices have almost tripled and some suppliers are no longer selling recycled chips. Only going to be more and more faulty/counterfeit eproms going forward.

Sellers are getting more creative with 'refurbishing' chips, got these last year:
20170523_103951.jpg

Typically for new designs that require small capacity 5volt chips, I will use SST39SFxxx Flash parts. Unfortunately they are not standard JEDEC pinout and are not backwards compatible.

After I got 100 of these repainted chips (approx 20% of them were faulty), decided no more buying used EPROMs.

So what are we supposed to do?!?!?!

https://www.digikey.com/products/en?keywords=AT27C

Start using OTP (one time programmable) non-erasable brand new off the shelf proms. They are available in 256/512/1024/4096/010/020/040/080 capacities/pinouts, and for a fair price imo
Click to expand...
OMG you're right!

They're repainted EPROMs!

24gki88.jpg


What the hell???

Still, I don't understand why they're faulty, I've reburned very old EPROMs (between 30 and 40 yo) victim of bit rot before without any issue.


fluxcore said:
I just get my shit from buyicnow and rarely get chips which have issues...
Click to expand...
Definitely a good solution, I've got hundreds of EPROMs to order/burn to fulfil the multi C2 demand.
They only ask $0.5 to burn the file.
 
twistedsymphony said:
Is there a good EPROM to OTP PROM part number cross reference somewhere?
Click to expand...
Check out the DigiKey link in my post. The part numbers are the same as common eproms. ie; M27C010 is AT27C010

Apocalypse said:
Still, I don't understand why they're faulty, I've reburned very old EPROMs (between 30 and 40 yo) victim of bit rot before without any issue.

fluxcore said:
I just get my shit from buyicnow and rarely get chips which have issues...
Click to expand...
Definitely a good solution, I've got hundreds of EPROMs to order/burn to fulfil the multi C2 demand.They only ask $0.5 to burn the file.
Click to expand...
My best guess why we are seeing chips like this, they want to start selling their inventory that tested bad years ago. If I had to guess window eproms havent been manufactured in >15 years, only so many things left to recycle and collect eproms out of. I'm sure the failures are due to storage/handling as recycled goods, before they're cleaned and painted lol

Don't think you're going to find any one reliable vendor in china for eproms now. It's been a big problem for people who make repro console carts and things like that
 
I just went through my blank chip inventory looking for painted ROMs...

This is what I found that was painted:
4x AMD AM27C020
4x ST M27C512
2x ST M27C801

Interestingly enough I know I've use chips from these lots and they were all good. I always buy in lots of 10, and I have a box where I keep the failed chips and currently there aren't any painted ones in there.

I have a lot of larger sized chips, I found it interesting that the painted ones were all of my smaller sizes.
 
Just got my first batch of repainted processors. These are worthless to us.

2h2dz40.jpg


Top is the repainted one untouched by me.

Middle is the paint removed.

Bottom is paint partially removed.

EDIT: Seems these should overclock to 10Mhz ok but still going to try to return/get money back.
 
fluxcore said:
I just get my shit from buyicnow and rarely get chips which have issues...
Click to expand...
I used to have a great track record with buyicnow until a recent batch of 27C400 chips. I ordered 10 chips, and only two of them would program successfully, and I tried using two different programmers. The 8 that won’t program all give “incorrect device ID” warnings from the programmer, which likely means that they are fake repaints-I’ll have to take some acetone to them later and find out.
 
Just received a lot of 10 27C040 from gc_supermarket where I usually buy my stuff.

They're painted (they look brand new and the writing is just too bright for 20+ years old) but they all burned perfectly so I'll continue buying my EPROMs from the same seller. The price on 040 has certainly shot up though.
 
27c512, 010, 020, 040 are available new from digikey and mouser in otprom form. (One Time Programmable) I'm switching to these for situations where I know exactly that the file I program is correct.

I'll keep good regular eproms around for testing and prototyping, etc.
 
Can you share some links or part numbers? I don’t mind one time programmable as long as they work. Heck I rarely ever reprogram EPROMs I use.
 
 
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