Are these MOSFETS fake or genuine? Please help!

[st2_998]

I'm looking forward to starting a P101, but I've some doubts about my mosfets. Bought on the bay in 2007.
Thanks for your opinions!

Image1
Image2
Image3
Image4

[Zen Mod]

try them

you have some papers at First Watt site - articles - testing mosfets

I had some - certainly fake Toshiba , but still good mosfets

[st2_998]

Originally Posted by Zen Mod

try them

you have some papers at First Watt site - articles - testing mosfets

Found it - thanks.
A fairly complicated thing for a non-expert, to be rigged up on a PCB (fig. 5 on the article) and requires 2 different power supplies, but probably you need it if you want a reliable result.
How about popping open a pair? Something more could be said lookin at the innards?

I had some - certainly fake Toshiba , but still good mosfets

I thought that fakes would be total wreck under the hood, waiting to burst in your face... I didn't expect something like a "good" fake!

[WuYit]

Hi,
they look very genuine to me.

[lineup]

Here is another thread with pictures.
Pictures of the 2SK1058/2SJ162?

[Jay]

I don't know if manufacturers start to lower their product build quality nowadays. I just CAN NOT believe a big Japanese company produce such a low quality stuff.

Their build (your pics) is indeed very poor!

I have plenty of laterals with me. I found only 2 types.

Type 1 (almost all): Below the FET type (such as K1058) I found company logo. Next to the logo is 3-character marking (such as 6K3). Below that is "JAPAN". Inside top left circle is a NUMBER. Inside top right circle is ALPHABET. Inside bottom circle is NUMBER.

Type 2 (only K2222): There is no "JAPAN". Inside top left circle is a marking like a star (but perfect star, not like your K1058, even worse the J162)

Your mosfet, fake or not, I'm 100% sure is built somewhere outside Japan. I don't believe Japan has such a low standard in manufacturing.

Later when you put your mosfet in the circuit, check the Vgs. It cannot be higher than 1.45V. Most of the time it is below 1V. But probably it is a lateral, because if vertical, it will need a temperature compensation circuit.

It may be original lateral. But if the external build quality is poor, the internal may be even worse, and of course logically the sound also

[ravslanka]

they are originals i bet

be a vegeterian

[st2_998]

Originally Posted by Jay

Inside top left circle is a NUMBER. Inside top right circle is ALPHABET. Inside bottom circle is NUMBER.

Type 2 (only K2222): There is no "JAPAN". Inside top left circle is a marking like a star (but perfect star, not like your K1058, even worse the J162)

Mine have a tiny combination of letters and numbers in top left circle (tht appears to be right), a letter in top right and a number in bottom left.
From K1058 spcsheet I see that a third text line on the face was added only later, so there could be Renesas K1058's bearing only "K1058" and "letter-letter-number" mark for batch.
From post 34 and 51 in the thread linked by Lineup it could appear that mine are genuine... I'll have to test them in some way. Thanks for feedback.

[WuYit]

Inside top left circle is a NUMBER. Inside top right circle is ALPHABET. Inside bottom circle is NUMBER.

Type 2 (only K2222): There is no "JAPAN". Inside top left circle is a marking like a star (but perfect star, not like your K1058, even worse the J162)

This is not generally valid.
It is sufficient to check the gate-to-source threshold voltage, reproducers are not likely to make the effort to manufacture lateral FETs.

[Jay]

Originally Posted by WuYit

This is not generally valid.
It is sufficient to check the gate-to-source threshold voltage, reproducers are not likely to make the effort to manufacture lateral FETs.

All I'm worrying is the build quality, not about fake or not. Those transistors shown by original poster do have very poor build quality. No doubt about it.

Now the question is, does build quality has correlation with sound quality??

From my experience, yes (and fake transistors always have poorer build quality), but let's put that aside. Just measure the Ciss and trans-conductance. If they measure better, even if the build quality is poorer, then they are better.

Many big manufacturers give license to small manufacturers to produce their products. These small manufacturers are given "standards" (quality control, quality assurance, manufacturing process, etc etc.) to follow. But different machines, different people, yields different output. During QC, some products are found to be too far away from the expected specifications. Where do these out-of-spec products go??