Those two identical FET are the suspicious SIR800 gave me trouble.
Yes, their position of big dot is not tally with real SIR800.
I think all SIR800 pics by Tom E have molded dot.
Molded dots don’t typically change color. Laser etched dots look more white because it burns into the surface. Same reason the lettering looks white. Who knows, it’s hard to tell by pictures.
They won’t most likely. I tried contacting a few manufactures about fakes in the past all to no avail. They either ignored me completely or gave me a run around and ended up saying I need to talk to the distributor I got it from, which was not possible of course. :person_facepalming:
Well, have you tried saying you’ve had fakes with the 5000pcs+ you’ve ordered?
I spent a few months trying to track down fake attiny85’s at one point, they were super slow to respond and after all that ended up getting no where and just saying to contact the distributor.
Some manufactures might be better to work with but the big ones just don’t seem to care for small orders like ours (small being anything sub ~100k units).
I’ve just sent an email to Vishay. Most likely they won’t reply me with helpful answer though.
On the webpage, Vishay acknowledge there are a lot counterfeits and advise their direct customer to buy from approved distributors only. But I think that doesn’t solve the problem of indirect customers buying a circuits having counterfeit Vishay components.
Let us know what they say, I have not tried contacting Vishay, I got fed up after trying 2 or 3 other companies first lol.
Sure. 
Having mosfet fever, so I bought 3 mosfet. Checking the resistance between D and S, they are all non measurable, that means they can be considered completely open. I will use the Infineon mosfet to repair another Haikelite TA driver and put it into my old MT03 12000lm.
And the two Haikelite SIR800 are each about 42Mohm and 55Mohm. This is good indicator it is not open enough.
Two SIR800, BSC009NE2LS5ATMA1, SIRA22DP-T1-RE3, NTMFS4H01NT1G
OMG Infineon mosfet is crazy. Now my old MT03 is the brightest. Much better than Vishay SIRA60.
Was too excited and forgot to mention this.
Both Haikelite TA driver having glowing during off with SIR800 mosfet. They are out of box defect, without extended use.
Both are successfully repaired by swapping with Vishay SIRA60 and Infineon BSC009.
Yep, that is what I expected. The FET is generally the weak link with this sort of issue.
Good to know you got them fixed!
I’m very glad that the culprit is confirmed.
I already have a replacement FET (BSC009NE2LS5IATMA1) thanks to Arrow’s free shipping but I need more soldering practice before I attempt the repair.
This is good to be aware of. I'm close to pulling the trigger on a MT03 TA. I guess I'll plan on ordering a new mosfet as well
I don’t think there’s much soldering involved. You need a hot air gun for mosfets.
Ya, FET definitely is the culprit in my two drivers.
I am glad it got sorted out and now I have over 32k lumens with two MT03 left and right. They got hot from cold really really fast. I plan to play with momentary mode side by side.
Thanks to you all who care, for all the help provided to me.
Yeah, I’ve got hot air. I just need to reflow quite a few more things before I take on my most expensive light.
That’s the craziest FET. I think you will notice at least 30% boost on brightness.
I didn’t practice, I was afraid of damaging FET with hot air, but it turned out working fine. Hot air temperature was 400c, I tried to complete it within 15s.
For modders, it is great light and really easy to open and repair or upgrade.
My FET is different from yours.
BSC009NE2LS5-I-ATMA1 vs. BSC009NE2LS5ATMA1.
I got the product number from Lexel but now I see that yours has lower RdsOn, higher current rating and lower price. Oh well. Anyway, it surely is a good FET. 