I have just received a couple of STK442-130 modules from an eBay seller located in the US. The chips have a 4D71 code on them. This code is the same I see on pictures from eBay sellers located in China, which makes me wonder if these chips are fake.
Any advise from the experts?
Any advise from the experts?
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Without opening them and comparing them with known genuine ... what else can I say but if you are not happy, send them back for a refund.
Thank you for your reply JonSnell,
I bought them as spares, so I don't have a non working original to open and compare.
I bought them as spares, so I don't have a non working original to open and compare.
I have bought tree pcs. with "P7S" stamped on them and I must say the are "Fake" I change them in a Genelec and they keep failing with SMOKE !!! So stay away from them.!!!
If they are like most fakes, they have a bunch of SMDs mounted on a PCB. The original types are chip and wire. If it’s not chip and wire, it’s FAKE - they are so blatant that a direct comparison is not necessary.
That.
They might be electrical equivalents, but no way SMDs on a PCB can dissipate as much as a bare chip mounted straight on substrate.
They might be electrical equivalents, but no way SMDs on a PCB can dissipate as much as a bare chip mounted straight on substrate.
You are expecting genuine STKs from eBay? These hybrid modules are long obsolete. If you're repairing something, try to make small discrete amp using Darlington pairs. Regards.
Yes, you are all right I do not think I can get a "Real" STK 442 any more, thought my supplyer send me tree other ones and we will see if they hold out !! I guess if you get the speaker repair at Genelec they will change the PCB board to a new chip type !!?
Modify the circuit, change to a current series amplifier, Mosfet, Chip amp, Class D, your choice.
STK were two channels or more at times in the same housing. Repair by mounting below higher on the heat sink.
You will have to use two sets of mono chip or other amps using the same power supply, or build a new one from scratch, if the existing transformer is not felt to be proper.
You will have to use two sets of mono chip or other amps using the same power supply, or build a new one from scratch, if the existing transformer is not felt to be proper.
Definitely not a real original. But maybe not a BAD copy. I’ve seen worse on THIS part. The power stage IS chip and wire, with proper heat spreaders. As long as the thermal path to the back plate is good it would survive normal use IF the power stage dies are correct. They may be since this is just a driver chip. The use of white goop is a concern - if they resort to using it then the dies may not have the proper passivation and will eventually fail from moisture ingress. In that configuration, they won’t fail from thermal. They at least TRIED. The small signal devices being SMD is not a concern in itself - if you were building one yourself this is how you would do it. If you used DPAK (TO-220 type SMD) properly heat sunk for the power stage they would be fine, and that would be the way to build it. The really bad fakes out there use SOT-223 or even SOT23 for the power stage and there is NO way to get the heat out of them. The resulting high operating temp causes failure…. Very quickly.
Although i strongly against counterfeit but as per my experience 'good copies' are quite capable!
As an example; a good copy of tda2050 could withstand +/-25vDC & 4ohm load without any problem(with somewhat underrated transformer).
As an example; a good copy of tda2050 could withstand +/-25vDC & 4ohm load without any problem(with somewhat underrated transformer).
https://www.diyaudio.com/community/threads/stk3152-stk3102-clone-for-aluminium-back-pcb.380947/
Go through this thread, there may be others too.
Here we get STK 4141 of decent quality, they are used in amplifiers, about $1.80, warning is not to change volume too fast.
It is 'decent copy', not original of course, bad copies are also sold from China.
Go through this thread, there may be others too.
Here we get STK 4141 of decent quality, they are used in amplifiers, about $1.80, warning is not to change volume too fast.
It is 'decent copy', not original of course, bad copies are also sold from China.
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The device in the photo is a decent copy, and with the advent of LED, the aluminum backed PCBs are easily available, so this is easier to make than earlier.
Try it, with a series lamp or Variac, and on load, some go bang if output open or shorted.
You can spray or varnish it to protect against moisture ingress.
Try it, with a series lamp or Variac, and on load, some go bang if output open or shorted.
You can spray or varnish it to protect against moisture ingress.
"funny" thing with these one is they burn out suddenly with no/small load and after 2-3 weeks use !!! So you think you are on safe ground But you are not !!! :--(
I got tree "new" types from my supplyer with different stamp I will give it a try ...... and pray !!!!
I got tree "new" types from my supplyer with different stamp I will give it a try ...... and pray !!!!