Fake STK-465

I never believed in it until I managed to get my first fake / counterfeit STK-465 chip, and I was very excited, because I had never seen one before. The seller was selling recycled chips, however the first chip he sent me turned out to be faulty so I contacted him, and he said that he would send out another, and to make up for the waste of my time, he would send a new chip instead. That sounded a little too good to be true but I figured let's play along and see where it leads...

It is not every day that one gets a fake, but it happens from time to time. If you get a fake, the thing to do is to photograph it so that others will be able to distinguish when they are buying. Sometimes people get upset when they get a fake, thinking that they might lose their money, however, it is un-necessary when buying on eBay, because of the first class iron-clad protection afforded to all buyers.

As an engineer -- when I have my engineering hat on -- I am very confident with my diagnostic skills, because electronics is a precise science. When I installed this chip, I was getting a hum on both channels, which indicates a DC offset. The speaker cone will pull in, or pull out, depending upon which half of the push-pull side is faulty.

At this point, there are no prizes for guessing that, the speaker terminals will exhibit a substantial DC voltage. By removing the wires to the input pins, you know that there is no input signal going into the chip, and that the chip must be generating this DC offset internally. At this point further investigation is not necessary, as the chip is faulty.

However, if you were new to electronics and not confident, chances are you would blame yourself, thinking that it must be something else that is wrong with the amplifier. After all, what are the chances of receiving two faulty chips from the same seller?

The psychology here is that you would not think that the seller had sent you a faulty chip, especially since he was trying to make up for sending you a faulty chip the first time round. Therefore, the second chip is not just a fake, but purposefully faulty, so that you would think that there was something else wrong with the amplifier.

I should be working for the police, perhaps the Chief of CSI division... :-)

Differentiating A Genuine From A Fake

Telling between a genuine and a fake is quite easy. A genuine original one will have engraved numbers, whilst this counterfeit one has clear printing in blue ink. As far as I am aware, there are no new chips manufactured, so if someone is offering you a new chip for three bucks then chances are that it might be fake.

On the original, the black plastic half is stuck to the aluminium with a very strong resin and you should not be able to prise them apart with your fingers. However, on the fake, you can prise open the case with little or no effort with your fingers.

This counterfeit one has these large square holes for the chip pins.

Notice the three holes without pins in them.

If inside the chip, you see a "peanut crumble" type resin mix then that too indicates a fake. If you are unlucky, this monstrosity will work for a short time in your amplifier, and fail after a few months when you least expect it. A few months are all it needs to work for because after that you no longer have the option to make a PayPal claim, or give negative feedback. However, if you are lucky, it will not work at all, or exhibit a hum, in which case you will remove it and contact the seller for a refund straight away.

Moreover, the big give away, is that if inside the chip you see discrete transistors, then that is a fake.

I managed to remove some of that resin with a small hammer and chisel, and found these power transistors underneath. As you can see one power transistor is missing its heatsink tab, indicating rejects or substandard components.

Someone put in a great deal of effort to make this. Slave-labourers and women often make it. This kind of stuff often leads to the sordid underworld of the Chinese labour market.

IRF511 is an N-channel enhancement DMOS transistor. However, this one looks like a fake because the fonts appear all wrong to me. It could also be a reject from their factory. However, it looks like the scammers are not clever as their supplier is swindling them. Of course, you cannot make a fake chip out of fake transistors; this is just plain stupid, however people always try.

If you want to see what a genuine one looks like from the inside, then have a look at the IMST Hybrid IC Design article. Also, have a look at all the previous articles, where I show a genuine one. You can compare for yourself by opening up all the pages in multiple tabs.

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