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?
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?
You should replace all 4. They're only $0.55 each.
IRFZ48VPBF for International Rectifier | Arrow Electronics Components
IRFZ48VPBF for International Rectifier | Arrow Electronics Components
If there are only 2, there are none in parallel and you definitely have to replace at least the one that failed.
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.
On the power supply side all thats there are the two fets and 2 diodes.
They're not in parallel. The drains are connected by the primary windings which have essentially 0 ohms of resistance.
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?
How could the amp work with one removed if what you say is correct?
It may work at a basic level but it most definitely wouldn't produce full power into its lowest rated load.
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
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
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?
Think i can replace them with these?
It's 36 vs 72 if you look at the 25C rating.
The 540s will work but won't be as reliable and will run significantly hotter. If this is your own personal amp, you can use whatever you want to use. If you intend to sell it, order the correct parts.
FETs don't have a collector. The center leg is the drain.
The 540s will work but won't be as reliable and will run significantly hotter. If this is your own personal amp, you can use whatever you want to use. If you intend to sell it, order the correct parts.
FETs don't have a collector. The center leg is the drain.
yea its my personal amp. its in pretty bad shape and had some water damage on part of the pcb but still works.
i put the 540s in and have been running it hard for about 2hrs and the output stage is much warmer than the power supply. Now I'm powering it off a modified atx psu with about 55A at 12.10v so i know i'm not moving as many watts as this amps probably rated at 14v.
I had those 540s left over from a repair i tried on a phoenix gold XS4600; i though the output fets were blown but it was some of the small pnp/npn transistors that were bad. might as well put the 540s to use
i put the 540s in and have been running it hard for about 2hrs and the output stage is much warmer than the power supply. Now I'm powering it off a modified atx psu with about 55A at 12.10v so i know i'm not moving as many watts as this amps probably rated at 14v.
I had those 540s left over from a repair i tried on a phoenix gold XS4600; i though the output fets were blown but it was some of the small pnp/npn transistors that were bad. might as well put the 540s to use
They'll run cooler than the outputs because they're operating in 'switch mode'. The outputs are running in linear mode and will dissipate much more heat. If it holds up for you and you're not going to sell it, there's no reason to replace them.
yea it seems fine.
if i order some fets in the near future for anything i'll probably pick up the right ones just to be safe but this amps probably going to pull test bench duty so maybe not.
Next project is a rockford t1000bd that the outputs blew up on. That amps in really sad shape and probably isn't saveable plus it has those stupid surface mount daughter boards clamped to the heat sync.
But i take what i can get to practice on 🙂
if i order some fets in the near future for anything i'll probably pick up the right ones just to be safe but this amps probably going to pull test bench duty so maybe not.
Next project is a rockford t1000bd that the outputs blew up on. That amps in really sad shape and probably isn't saveable plus it has those stupid surface mount daughter boards clamped to the heat sync.
But i take what i can get to practice on 🙂
If you don't have the tutorial...
Read this:
http://www.diyaudio.com/forums/car-...-schematics-3.html?postid=1901581#post1901581
And watch this:
http://www.bcae1.com/temp/rockfordsolderingtransistorsdown01t.avi
Those should help.
If you have any further questions about the Rockford amp, start a new thread.
Read this:
http://www.diyaudio.com/forums/car-...-schematics-3.html?postid=1901581#post1901581
And watch this:
http://www.bcae1.com/temp/rockfordsolderingtransistorsdown01t.avi
Those should help.
If you have any further questions about the Rockford amp, start a new thread.
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