Are these MB510 ICs fake? - Page 1
Forum section: electronics / projects

author: james_s
author_rank: Super Contributor
timestamp: June 15, 2020, 05:20:08 am
content: After the first ones I bought turned out to be fake (not even the right package, they were too narrow) I ordered a pair from another seller and these finally showed up. They're the right footprint this time at least but there are some red flags. The top had a slight texture that made me think blacktopped so I scrubbed it on a paper towel soaked in acetone and got a slight brown smudge on the towel but the numbers didn't rub off. I went ahead and installed one on the board and was disappointed to find it doesn't work, I get an approximately 4MHz square wave on pin 4 with nothing on the input, doesn't seem right but it's possible there's another fault on the prescaler board. The next red flag I noticed while photographing the ICs, they came side by side in IC tape a if they were cut from a reel but looking at the bottom they each have different stampings.Thoughts? I just want to be 100% certain before I accuse the seller of sending me fakes and put in a claim for a refund. The lighting was different for some of the photos, they're actually the same shade however as it appears, the bottom is glossy and the tops have a bit of a texture to them.

author: magic
author_rank: Super Contributor
timestamp: June 15, 2020, 08:05:23 am
content: The top does look suspicious with those diagonal stripes. Are the sides glossy too? What if you rub it more? The markings are laser-cut so they will never come off, but perhaps the surface?I think the numbers at the bottom indicate position in a multi-package mold or something like that. I could never find any meaning in them and often noticed that they aren't identical on chips from one batch.

author: james_s
author_rank: Super Contributor
timestamp: June 15, 2020, 08:05:57 pm
content: I'll try rubbing it some more and see what happens. The stripes may just be from rubbing on the paper towel before, but I'm suspicious that they are sanding marks that have been blacktopped and then re-marked.If not a prescaler, I wonder what this IC could be that is resulting in a 4MHz square wave? I suppose it's possible that the input stage is oscillating but I didn't see anything on the scope. Not that I'd expect much from a passive probe at >500MHz which is what it would be with the IC set to divide by 128.

author: amyk
author_rank: Super Contributor
timestamp: June 16, 2020, 02:45:32 am
content: Fast ICs like that can definitely oscillate if given a chance to.

author: bin_liu
author_rank: Contributor
timestamp: June 16, 2020, 04:13:44 am
content: Looking at the first picture, the traces of polishing are obvious.This is a refurbished, or even renumbered IC.In China, there is such an industry.Feeling embarrassed.

author: james_s
author_rank: Super Contributor
timestamp: June 16, 2020, 04:15:55 am
content: Quote from: bin_liu on June 16, 2020, 04:13:44 amDon't worry about it, I don't hold the entire country responsible for the acts of a few. I wonder what these ICs actually are?

author: magic
author_rank: Super Contributor
timestamp: June 16, 2020, 06:34:11 am
content: Don't turn it on, take it apartIf you have a known good chip for reference, measure in diode or ohms mode between various pins. It often gives a clue that a chip is completely wrong. I assume that you CBA to build some minimum test fixture to verify proper operation outside the circuit you are repairing.

author: james_s
author_rank: Super Contributor
timestamp: June 16, 2020, 06:37:30 am
content: I don't have a known good chip for reference, I've failed to come up with a source for one. I had no idea they were unobtanium until I'd already had some boards made and got the other bits.

author: magic
author_rank: Super Contributor
timestamp: June 16, 2020, 07:03:05 am
content: Hmm, looks like it's basically a simple counter and the test jig schematic is trivial. I imagine it shouldn't output 4MHz (or anything) if you put it on a SOIC breakout board, bypass closely with 100nF and tie all inputs to ground.At least the GND/VCC/OUT pins appear to match a real MB510What about others - are some of them NC though they shouldn't, is the NC truly NC?

author: Bud
author_rank: Super Contributor
timestamp: June 16, 2020, 02:53:02 pm
content: I used GHz range prescalers and they output a frequency with no source signal on the input. They output the correct frequency when fed a source signal. I always buy my parts from Digikey. It was several years ago but i remember that i was not concerned, apparently because that behaviour was described in the datasheet as normal.

author: Achu
author_rank: Contributor
timestamp: June 16, 2020, 05:06:33 pm
content: Why would they go through the trouble of renumbering one IC into other and sell it?

author: wraper
author_rank: Unknown
timestamp: June 16, 2020, 05:14:03 pm
content: Quote from: Achu on June 16, 2020, 05:06:33 pmBecause they can sell one thing as another and earn some money by doing so. That's how counterfeiting business works. Were you born yesterday?

author: james_s
author_rank: Super Contributor
timestamp: June 16, 2020, 05:40:58 pm
content: Quote from: Achu on June 16, 2020, 05:06:33 pmBecause it's possible to turn a pile of worthless obsolete parts into rare ICs that can be sold for several dollars each. Is it not obvious?

author: james_s
author_rank: Super Contributor
timestamp: June 16, 2020, 05:41:58 pm
content: Quote from: magic on June 16, 2020, 07:03:05 amYeah I'll stick one on a piece of copperclad and see what happens with the test circuit. I haven't checked the NC pins yet but I'll look at it after work.

author: Achu
author_rank: Contributor
timestamp: June 19, 2020, 02:23:23 pm
content: Quote from: wraper on June 16, 2020, 05:14:03 pmLast week actually

author: GigaJoe
author_rank: Frequent Contributor
timestamp: June 20, 2020, 02:11:00 am
content: usually it visible different colour tone on edge if it blacked, I use an acetone to rub the top, it wiped black , if exist, acetone don't dissolve plastic and leave no trace if it no dyesecond thing 1635 - date ? ; 2016 -I see a lot sellers with 1635 -- most likely re brand of something similar ...probably this one would be ok, but who knowshttps://www.aliexpress.com/item/33051508729.htmlhttps://www.aliexpress.com/item/4000109899134.html

author: james_s
author_rank: Super Contributor
timestamp: June 20, 2020, 02:20:38 am
content: Guaranteed those are fake, they're way too cheap. I think this is one of those chips where all of the ones being sold out of China are fakes, they seem to be unobtainium.

author: GigaJoe
author_rank: Frequent Contributor
timestamp: June 20, 2020, 04:09:14 am
content: price on the used market not reflecting an actual price, it more liquidity, most "hi-end" audio op-amp are fakei even see the same re branded to be a better look , not like 1997 but 2017 ...how about thathttps://www.utsource.net/itm/p/1745738.html