LM1875 Original or fake ?

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Gold_xyz

Gold_xyz

Member
Joined 2005
TDA1875 Original or fake ?

Hallo ! :hohoho:

I have purchased five tda1875 to build a Multichannel amplifier.
Today when I have gone to withdraw I have noticed them that the pins are folded up in different way. :scratch:

these are the photos:
An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.


the original from datasheet :
An externally hosted image should be here but it was not working when we last tested it.


Datasheet from factory :
http://www.national.com/ds/LM/LM1875.pdf

Original :D or fake :bawling: ?

tnx !
 
Dxvideo

Dxvideo

Member
Joined 2003
ozgurkolay.com.tr
Hi Gold,

Most possible its FAKE... There are a lot of fake LM chips on market... Have a look to pin tips. I've never seen any like that.. And if its not a second hand IC, why has many scratchs on its case? I bought two LM1876 from a local market and they were look like your LM1875. Now they're in trash bin... Because they burned (from my fault, but probably they would burn even i made everything ok). I recommend; dont use them.
 
jpg

jpg

Member
Joined 2003
I can only compare to my LM3875s, which are the only LM chips that I've ever closely examined.

1) The form of the pin tips of your (alleged) LM1875 look different both from my LM chips and from the specs.

2) As you can see in the specs, the pins should all be stepped, not only those in the front row. In your photo, it looks like the pins in the back row are straight!

3) The bend of the pins in the front row looks much sharper on my chips and in the specs.

4) It's hard to tell, but the metal back of your chip looks more coarsly machined then mine.
 
Gold_xyz

Gold_xyz

Member
Joined 2005
Hallo ! :santa2:

Now it is official, they are fake ... :dead:

This is the answer of National Semicon :
"Henry,
Based on the topmark of the device, the part was most likely not manufactured by National Semiconductor.
Thanks. "

I am desperate now I have to order from another supplier and to hope that he have the true ICs... :rolleyes:

bye. :xmasman:
 
dfdye

dfdye

Member
Joined 2005
GG said:
Have you tried hooking one up? You can test it easily with a few resistors and aligator clips.

It seems like a lot of work to make fake $2 chips.
Click to expand...
If you make 100K at $0.20 a piece and sell them for $1.00, you are undercutting national by >$0.50 per part and stand to clear $55,000. In a lot of parts of the world, this is a HUGE pile of cash. Multiply that by the number of fake transistors, etc. that are on the marked and you have a huge profit potential. Once you have the tech set up to build these devices, you can crank tons of them out for next to nothing.

Same for fake drugs, etc. You can buy a pill press that will make Viagra-looking tablets, put in 50% of the API that Pfizer does (sub-contract an Indian synthetic lab to make the drug for you), and make a killing selling pills over the intar-web.

The analogy goes one step farther: fake drugs and fake semis both will probably work how they are intended, but not nearly as well as the real thing. People buy fakes because they are cheap and will often work fine, but they will NOT have the same tolerances or performance as the genuine item.

So, even if these chips DO work, I would be hesitant to skimp the extra few $$$ for a new set of authentic chips. You may well have the good luck that burnedfingers did, but I would rather not roll the dice if it were me.
 
jpg

jpg

Member
Joined 2003
Good post, but ...

People buy fakes because they are cheap and will often work fine
Click to expand...

... if by "people" you mean end customers, I think they buy fakes because they believe they buy genuine chips at a good price. I doubt that anyone who buys chips to use them for a DIY hobby would knowingly buy subpar (at best) performing chips to save, in the case of the LM's, one or two dollars pp.
 
dfdye

dfdye

Member
Joined 2005
jpg said:
... if by "people" you mean end customers, I think they buy fakes because they believe they buy genuine chips at a good price.
Click to expand...
Touche. I intended middlemen (usually unethical) as the people who would intentionally buy fakes. I indeed doubt that hobbyists would intentionally buy fakes, but as burnedfingers pointed out, some people have gotten fake parts and used them successfully. My post was intended as a disclaimer that, though these parts may indeed work for a while, they are not ideal and should be avoided despite POSSIBLY working. The risk isn't worth it. Buy new, genuine parts and avoid possible headaches down the road.
 
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