STK4191V and other STKs... and counterfeits?

[eccerr0r]

Re: STK4191V and other STKs... and counterfeits?

hmm...that is true, the dc blocking caps don't make sense with differential supplies...must have been some other filter caps that I mistook for the output caps.

The specs look like the STK cannot handle shorted outputs however, it seems to imply a 2 second limit for output shorts ... the "speaker protection relay" is supposed to protect the ...what? Speakers? or the amp module?

[budm]

Re: STK4191V and other STKs... and counterfeits?

Think about it, what will happen if the internal output transistor shorted out, it will dump the full VCC (+ or - depend on which Transistor shorted out) into the speaker and you will see nice smoke coming out from your speaker.
The speaker relay has circuit that detects the DC at the output of the amplifier, if it see around 2VDC or so (typical) then the relay will disengage the speaker from the output of the amplifier and most speaker relay also has delay circuit (2~3 seconds typical) to reduce the turn on pop.
http://sound.westhost.com/project33.htm

[budm]

Re: STK4191V and other STKs... and counterfeits?

http://www.daycounter.com/Calculator...lculator.phtml

If you know the thermal resistance of the heatsink then you can estimate the Junction temperature, but I doubt that you will be listening to the constant sine wave at full power.

[eccerr0r]

Re: STK4191V and other STKs... and counterfeits?

Perhaps the reason I've never thought of these situations is that I've never bought expensive or high wattage speakers before, and blowing speakers as a result of a burnt amp has never been an issue - just replace both... However a short causing amp damage, well, that's a different story... but that seems like an exceptional case too...

Finding the thermal resistance of an arbitrary heatsink will be a challenge on its own... I do have a resistor that can be bolted at a point but need to insulate it such that all of the heat is coming out to through the junction...

[budm]

Re: STK4191V and other STKs... and counterfeits?

I would not worry about the IC being over heated at this point since I doubt that you will running it at 25 Watts continuously or more.

[eccerr0r]

Re: STK4191V and other STKs... and counterfeits?

If I were repairing this device for someone else...then how would people ensure that there would be no callbacks?

[budm]

Re: STK4191V and other STKs... and counterfeits?

There is not much you can do due to the design by the manufacturer unless you want to do the modification to improve it. Just tell customer the truth.

[eccerr0r]

Re: STK4191V and other STKs... and counterfeits?

And then we still can't tell if the STK are real or not...

[budm]

Re: STK4191V and other STKs... and counterfeits?

And then we still can't tell if the STK are real or not...

Well, there is not much you can do about that unless you take it apart and compare it to the original.