Defect Transistors in Hifonics Brutus BX1500D

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Hello, I have a problem. I have a Hifonics Brutus BX1500D. There are some transistors defect in the audio area, NOT in the power supply.

The transistors has got some numbers and letters.
94-2355
I R 426H
01 2F

I can´t find which transistor it is or an replacement typ.

Here are some pictures:

http://img180.imageshack.us/img180/2971/p1010010cf3.jpg

http://img515.imageshack.us/img515/2258/transistor1ke8.jpg

So please can someone help me to find out which original transistor was build in?
Or can say with replacement type I can use.
Only one side has got defect transistors. So I will change every transistor on this side. Is this correct?
Regards Jörg
 
The originals transistors in some of those amplifiers were IRF3710s. There is a problem with some of the 3710s that will cause the amp to go into protection mode.

Someone is supposed to bring me a similar amp tonight to test a different version of the 3710. If I get the amp, I'll test both sets of 3710s and post the results.

If you have some IRF3415s on hand, they will allow you to get the amp up and running and check for other problems.

In virtually all of these amplifiers, when the outputs go, the HIP4080 fails also. If you have to order parts, order a couple of the 4080 ICs. If you fail to find all of the defective components, it's likely to kill the 4080 again. They are very sensitive and fail in a fraction of a second. There is zero protection in the output driver section of the IC.

You can change only one half of the FETs but if the amp failed due to a shorted speaker or similar fault that caused high current to pass through the outputs, you should change all of the outputs. If the amp failed under normal operating conditions and there are no faults in the wiring, you can change only the ones operating in the half of the H-bridge with the failed FETs.
 
Hello, sorry my Englisch is not so good and I have problems to understand the text.

Is it right, that some IRF3710s make problems? But the IRF3710s looks different from the IRF3710. Can I build in the IRF3710 or IRF3415?

IRF3415=V-MOS, 150V, 37A, 150W, <42mê(22A)

IRF3710=V-MOS, 100V, 49A, 150W, <25mê(28A)

With of them I have to installed?
I want to install the IRF3710. Is this ok?

And another question: The IC HIP4080AIP can also be damaged? So I have to change it with a new HIP4080AIP or can the IC be ok and I have not to change it? Perry Bain write that the IC 4080 often goes defect.

Regards and sorry for my English.

Jörg
 
Sorry for the confusion. The lower case 's' on the end of the part number IRF3710 was plural, not part of the part number.

I only suggested the IRF3415s as a temporary fix if you had them on hand.

I did a bit of testing on two amplifiers. The first was a Brutus BXI1606D. The IRF3710 (no suffix) worked in it.

The second amp was a Hifonics XS1500.1 Stealth. I had previously installed IRF3415s in it and the amplifier worked well with them. I installed IRF3710 FETs and the amplifier would immediately go into protection. Even before the speaker protection relay would engage, the amp would go into protection if audio was driven into it. I pulled the IRF3710 FETs and installed the IRF3710Z (note the Z suffix) FETs in the amp and the amp worked as it should.

In many amplifiers using the HIP4080 IC, the non-suffix IRF3710 FETs are not a good replacement even if that's the original part number that was used in the amplifier. I've had limited experience with the Z suffix version of the 3710 but they seem to be significantly different in their operation. I asked another tech if he had found any amps that had a problem with the Z suffix version and he hadn't.

It's always better to change the HIP4080 IC. They almost always fail when the outputs fail.


One more note... The supplier (Digi-Key) part number is IRF3710ZPBF (PBF = lead free). The part number on the FET is IRF3710Z. The assembly line code has the letter 'P' in it indicating lead free. See attached.

I know that this may be more information than you wanted but this can help avoid the problems that I've encountered.
 

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The Z version of IRF MOSFETs features a body diode with much faster reverse recovery (lower Qrr and Trr, see datasheets). This makes a big difference in class D output stages because a cross conduction spike is always produced during reverse recovery on each switching cycle, and the slower the body diode and the faster the turn on, the bigger the spike becomes. When a set of "standard-body-diode" MOSFETs are placed in a circuit whose gate drive (and current limiting) is designed for "fast-body-diode" types, this spike may cause false triggering of the overcurrent protection or may even blow the MOSFETs. The "standard-body-diode" types need slower gate turn-on to tame the reverse recovery spike at the expense of more heat wasted.

"Z" IRF parts are preferred for class D output stages, even if the original wasn't (it could have been a special lot anyway). On the other hand, body diode does not matter for push-pull power supply MOSFETs.
 
JoergST:
I tried the IRF1310N in some of the amplifiers that were finicky about the FETs used and they didn't work. They had the same problem as the IRF3710. If you get the IRF1310 FETs to work properly or if you use a variation of the IRF1310, please post your results.

Eva:
Maybe you can help determine why some FETs work and other don't. The Trr and Qrr don't seem to be the determining factor. This is what I've found.

Amp A (HIP4080 based system):
IRF3710 did not work Trr=140nS Qrr=0.67uC
IRF3710Z works Trr=50nS Qrr=0.1uC
IRF3415 works Trr=260nS Qrr=2.2uC

Amp B (MTX6500 and similar with less than 75v rails)
SSP45N20A works Trr=210nS Qrr=1.67uC
SSP45N20B does not work Trr=245nS Qrr=2.27uC
IRF3415 works Trr=260nS Qrr=2.2uC
 
Perry Babin said:
JoergST:
Eva:
Maybe you can help determine why some FETs work and other don't. The Trr and Qrr don't seem to be the determining factor. This is what I've found.

Amp A (HIP4080 based system):
IRF3710 did not work Trr=140nS Qrr=0.67uC
IRF3710Z works Trr=50nS Qrr=0.1uC
IRF3415 works Trr=260nS Qrr=2.2uC

IRF3710: Qg=130nC max. | Qgd=43nc max. | Crss=72pf typ.
IRF3415: Qg=200nc max. | Qgd=98nc max. | Crss=340pf typ.

Given the same gate drive circuit, IRF3415 will turn on much slower due to the increased Crss and Qg. This is something to consider.

Amp B (MTX6500 and similar with less than 75v rails)
SSP45N20A works Trr=210nS Qrr=1.67uC
SSP45N20B does not work Trr=245nS Qrr=2.27uC
IRF3415 works Trr=260nS Qrr=2.2uC

IRF3415: Qg=200nc max. | Qgd=98nc max. | Crss=340pf typ.
SSP45N20A: Qg=117nC typ. | Qgd=49nc typ. | Crss=255pF typ.
SSP45N20B: Qg=133nC typ. | Qgd=67nc typ. | Crss=120pF typ.

Again, given the same gate drive, SSP45N20B will probably turn on much faster than the other two due to the lower Crss, while having a slower body diode.

Actually you could patch these amplifiers to use whatever similar parts you have in stock by tweaking the gate resistors. I use to do it that way, mostly because I don't get many amps to repair and I can't afford storing a lot of different pars. If you double the value of the gate turn on resistor (be careful to keep the same or greater turn off speed) you will probably get IRF3415 to work in these two amplifiers, and also SSP45N20B.

For 100V and less my favourite device is IRF540Z (do not mistake with the other older versions). Check the datasheet and you will see why. You can repair most low-voltage class D stuff with it, although it may require slowing down the turn on due to the low gate charge and capacitances.

Note that those damn manufacturers are making class D automotive subwoofer amplifiers with ultra-low-cost surplus or discontinued parts that were never intended for class D. They use to take the "last time buy" bargain offers that the manufacturers use to get rid of the stock leftovers of transistors that are going to be discontinued.

BTW: I'm starting to plan a compact 12V-powered 4x150W full-range class D amp and it will use IRF540Z. The class D control scheme is going to be my own derivative of self oscillating UcD (see class D forum). The power supply is going to use IRF2907Z (this is a total winner too, you can replace almost anything by one or two pairs of these).
 
Gate charge and capacitance are high, but Rds-on is only 0.0035 ohms so one of these can replace several higher Rds-on devices resulting in little overhead for the driver circuit. Think of those amplifiers with 6 pairs of IRFZ34N (Rds-on=.040 ohm). Other of my favourites used to be IRFZ48V and HUF75344 (now discontinued).
 
Hello every body. I have an amplifier like this. I receive from a friend. Six transsistors from power suplly area are burnt.

I want to know if i change those transistors, if it exists any problem, i reffer to other electronics components that can be damaged. I forgot to say... i found some resistor damaged in the front of the transistors(100Ohm) I found original transistors and they aren't cheap.... and if i put those and they get damaged i will kill myself.

Could you say what to ckeck? Six of the transisitors are good(12 total), and the amplifier works fine, i heard a coil noise, and the idle current is about 2A. I can't explain how this amplifier works with so much burnt transistors....

Sorry for my english....
 
As long as the supply with the low voltage supply windings is operating, the amp will operate (at reduced power).

You need to confirm that you have a good drive signal for the FETs that failed. Measure the DC voltage on the gate pads (where leg 1 of the FET solders into the board). It should be the same as for the FETs on the other side of the amp.
 
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