kicker kx200.2 shorted IRFZ48V

[ComputerJLT]

so I have a little kicker kx200.2 that was given to me non working. Turns out one of the IRFZ48V fets were shorted internally in the power supply. There are 2 of those fets paralleled.
I removed the shorted fet and the amp works fine but i'm worried about only running it off of just one of the fets.
Looking at the data sheet it looks like the constant drain current for that fet is 50A at 10v at 100c. This amps only rated at 200w bridged and only has a 30a fuse. Should I bother replacing the fet or just run it till this one pops?

[Perry Babin]

You should replace all 4. They're only $0.55 each.

IRFZ48VPBF for International Rectifier | Arrow Electronics Components

[ComputerJLT]

But there are only 2 in this amp?

They were $2/ea on digikey but i like your link better lol

[Perry Babin]

If there are only 2, there are none in parallel and you definitely have to replace at least the one that failed.

[ComputerJLT]

Unless im going crazy there are 2 fets both in parallel, both drains on had continuity even w the shorted fet removed.

On the power supply side all thats there are the two fets and 2 diodes.

[Perry Babin]

They're not in parallel. The drains are connected by the primary windings which have essentially 0 ohms of resistance.

[ComputerJLT]

Lemme pull the pcb out again andbtake pix, now you have me second guessing lol.


How could the amp work with one removed if what you say is correct?

[Perry Babin]

It may work at a basic level but it most definitely wouldn't produce full power into its lowest rated load.

[ComputerJLT]

ok i was wrong; the collector (input of the fet? still new to the terminology, right most pin looking at the writing) of both of the FETs are connected to the GND terminal on the amplifier. The center pins do go to two separate windings on the Traffo. It looks like there are two primary and two secondary windings (2 sets, 4 pins of multi conductor thick wire; and two sets (4 pins) of thinner wire on the opposite side of the torrid). Its not like there is a center tap there are 2 seperate windings that the fets are connected to; different color even.

Is that correct that there are two primary windings? if so is that normal? that seems so strange to me.

Anyway thanks again for the input Perry!

Knowing this i'm for sure replacing the fets. Do I have to order the same ones? I think i have some good fets that came out of a power supply laying around somewhere, maybe IRF510 or 540 i dont recall the p/n exactly

[ComputerJLT]

found em; two IRF540Z both N channel hexfet mosfets by international rectifier. Only difference i see is the 540s are rated at higher voltage but not as many amps (36a vs 51a).

Think i can replace them with these?