Replace power MOSFET in subwoofer plate amp, Sledge STA-1000D

[nainokami]

Welcome to the forum. What country are you in? I might find something closer to you.

https://www.questcomp.com/part/4/sp..._source=findchips&utm_content=standardpricing

Thanks a lot. I need those as well, but I need the small driver as well (8 pin DIP). I’m in Denmark. I don’t know if a replacement was ever identified.

 

[PETERDECO]

What is the part #? Never mind. I see it was never identified.

 

[kootlave]

To anybody out there still searching and trying to identify this part.
i have contacted one reputable electronics components seller from aliexpress and i go this response:
As you can clearly read it, the component original part no was ITCHED AND ERASED By formosa the company OEM manufacturer of the subwoofer plate amplifier INTENTIONALLY To prevent anyone from repairing their products if they fail.
SMS5408 Is not the actual part no, there's absolutely no part carries that part no, its just an attempt from formosa company to fool anybody who wishes to repair their unit that there are NO AVAILABLE SPARE PARTS Which is false because its actually available.
i reviewed this YouTube video as well and in the comments, one person mentioned that the part is not MOSFET BUT ACTUALLY AN IGBT !!!!

So the GDS Markings on the board ARE ALSO WRONG AND JUST AN ATTEMPT TO MISLEAD ANY PERSON Who wishes to carry out a repair, i have contacted the person who wrote the comment as well as the video poster but with no replies.
Conclusions: BOTH THE SMS5408 PART NO AND BOARD GDS Markings ARE NOT CORRECT AND INTENTIONALLY IMPLEMENTED THERE TO MISLEAD ANY PERSON AND MAKE THEM GOES IN CIRCLES AND NEVER FIND A SOLUTION.
Bottom line: the board needs to be reversed engineered by someone who have an in depth knowledge of electronics circuits and their design to figure out the characteristics of those parts and figure out a substitute replacement parts which is simply beyond my knowledge.
hopefully someone out there with the initiative and enough solid scientific background can help one day

 

[Jackal]

Don't get bogged down with the Gate Source Threshold voltage. Mosfets invariably require 10V on their gates to become fully enhanced. The VGs threshold is largely immaterial in a switching circuit. They are either on or off. The driving device will be designed to accommodate this.

Where did you learn electrical engineering? Ive seen mosfets which saturate at every voltage level immaginable, full current. Logic Level Mosfets are built with Vgs 5v and 3.3v IE "logic level". Actually a 10V Vgs, even with "full" current allowed saturation levels are pretty rare. Did you look at one datasheet graph and come up with this conclusion?
I hope that your beliefs are not set in stone. Please learn some more at your own expense before attempting to advise others. Incorrect information can be very detrimental to someone who doesn't know any better.

 

[Jackal]

Thanks a lot. I need those as well, but I need the small driver as well (8 pin DIP). I’m in Denmark. I don’t know if a replacement was ever identified.

Most companies who make electronics hide/ sandpaper/ polish, etc the ic chips to avoid any easy copying or fixing their equipment. I assume you are talking about a gate driver. If so perhaps maybe I can be helpful in determining the mosfet. Although mosfets are "voltage" driven devices, some larger ones still require a certain amount of current to provide for its "charge" capacitance. Be sure to check datasheet for "gate charge" of a mosfet. You also need to know how powerful the gate drivers are, but to determine the correct voltage (Vgs), the Vgs has to be established before the driver (as an input). You could determine the factory level based on the input pin of the driver while on. It would be a stable "always-on" voltage probably on the left side of the gate driver ic. I havent seen too much on the board, but I was given a PB13 ultra recently to determine its problem. Ive seen the same common layout before in ATX psu's. I normally work with 12v electronics, but there's not too much difference. I would like to know if anyone has found a "protection chip" for OCP, OVP, UVP, UCP, etc. Thanx

 

[Jackal]

Most companies who make electronics hide/ sandpaper/ polish, etc the ic chips to avoid any easy copying or fixing their equipment. I assume you are talking about a gate driver. If so perhaps maybe I can be helpful in determining the mosfet. Although mosfets are "voltage" driven devices, some larger ones still require a certain amount of current to provide for its "charge" capacitance. Be sure to check datasheet for "gate charge" of a mosfet. You also need to know how powerful the gate drivers are, but to determine the correct voltage (Vgs), the Vgs has to be established before the driver (as an input). You could determine the factory level based on the input pin of the driver while on. It would be a stable "always-on" voltage probably on the left side of the gate driver ic. I havent seen too much on the board, but I was given a PB13 ultra recently to determine its problem. Ive seen the same common layout before in ATX psu's. I normally work with 12v electronics, but there's not too much difference. I would like to know if anyone has found a "protection chip" for OCP, OVP, UVP, UCP, etc. Thanx

Opps, didnt see the IGBT part. So they used BJT+Mosfet. Well, thats interesting, but I think a compatible Mosfet can still be determined. I will repost how and what it is, after I troubleshoot the board I just received. As you know, Ive got to strip alot of glue/ adhesive first.

 

[Delta Prime]

As you know, Ive got to strip alot of glue/ adhesive first

Make sure it's in a well ventilated area...

Where did you learn electrical engineering? Ive seen

Nice intro. Who cares..who are you...?