Hello, I received an amplifier with missing output mosfets.
The rail caps have 200vdc, should I use 24n50,or could be the 400v mosfets enough? Driver card is standard with irs 21844s.
The rail caps have 200vdc, should I use 24n50,or could be the 400v mosfets enough? Driver card is standard with irs 21844s.
It comes out of the factory with FDA24N40F. No need for 500v mosfets. 400v are enough. There are never 200vdc even with 15-16v of B+ input. At least the two i've repaired did not make 200vdc.
There are 2 version of this amp.
SPL and HC.
In SPL FDA24N40F are OK.
In HC FDA24N50F are required.
SPL and HC.
In SPL FDA24N40F are OK.
In HC FDA24N50F are required.
The differences from the hc and non hc is the rail voltage.
This appens for the regulation circuit.
The SPL version is regulated, so at 12.6v and 13,8v the rail is +/-165v.
at 14.4v the rail are +/-172v
In the HC version, the rail is dipendent from vBatt.
At 14.4v i've measured +/-207v.
yuo can mount 24n40 but you must lower the rail increasing dead time in power supply.
Both SPL and HC have 200v caps, it is strange but it is so.
I have repaired many GZ10000SPLs and many GZ10000SPL-HCs and all HCs have shown a rail slightly above the cap threshold when operating at 14.4v.
The caps probably have a good tolerance threshold, or the designer has considered that when you use the amplifier hard, 14.4v will never be present and therefore the rail will drop drastically.
My question is: if I turn on the system with little volume or simply for some time I turn it on but I don't play music?
Fortunately, however, all the HCs that I repaired, never had the caps exploded or swollen, so they are ok.
Keep in mind that when the output mosfets are not mounted, the rail goes even higher (over 230 volts).
Having said that, FDA24N40F could also work, but since you are at the bearable limit, it is "ultra recommended" to go with FDA24N50 F or nonF, or, as I said before, to force the power supply to have a longer dead time, to generate a rail of at least 35v less.
You will lose power, but at least you can use 24N40, otherwise you must sell or stock the 24N40 and buy the 24N50.
The only problem is that 24 mosfets (both 24n40 and 24n50) are expensive.