Hi! I am trying to repair my deaf bonce AAP 400.4 amplifier after I accidentally shorted the outputs, I think I’ve identified these mosfets as the problem but I can’t find where to buy them, it only says 2206 on it(I think S3 is the position on the board because there’s S3 written on the board where the mosfet is) does anyone know what brand/model they are? Or can I use some other mosfet instead of these?
Welcome to the technical forum. I do not like the response I am going to provide. I am in agreement with you if the S3 is on the board, it very well could be for the board location. Seeing the generic 2206 with no Manufacturere logo and possibley the board location on the chip itself makes me believe it could be proprietary. I have looked and I am unable to verify. Though I am not the only one that reads these posts and responds. Someone else might be able to help. So there are others in our group that watch. Plus our external customers, So hopefully someone might be able to help.
497-13589-5-ND (click here) might work as a replacement. However, there should be protection circuitry on the amp preventing damage to it, a lot of the time it can be a blown fuse. I might suggest looking elsewhere on the board for damage, circuitry more near the speaker output, could be one part in series such as a capacitor, resistor, diode etc. Shining a flashlight through the PCB board (once you have it out of the aluminum frame) is a good way to read for any brown spots on the board if a part is burnt.
Okay thank you! I’ve checked all the capacitors and don’t think they are broken although there is something fishy about two of them, they read 9200uF but say they are 4700uF. I just chalked it up to my cheap multimeter not being accurate because the resistance test checks out and they can hold charge. These two mosfets are shorted between drain and source which leads me to think they might be fried. The gates and sources of these moafets are connected to the same pins on the speaker outputs.
Hi antonkarlsen
Usually when something shorts the high heat generated will change the color of the board, clearly seen by using the flashlight method (shining through the board), but in a case like this where the output was shorted for only a second or two, this would not normally cause discoloration of the PCB making it harder to troubleshoot.
Sounds like you are on the right track however. It is possible the 4700uF are both in parallel to give roughly 9400uF. Once you narrow down which parts you believe are bad, measuring them individually when pulled-out of the board will give you direct readings so you would be able to verify the part is bad before ordering. Of course there always is the possibility that other parts may still be bad on the board, since when one part fails it may fail others.
The gates and sources of these moafets are connected to the same pins on the speaker outputs.
-I assume you meant the drains and sources?
Hello and thank you! I desoldered the two capacitors that said 9200uF and they were connected in parallel to make 9400uF like you said, I also desoldered the two mosfets I thought were bad but they too were good. I tried some other capacitors I was suspicious of but sure enough they were good too. I’m now stuck and don’t know what else to do or look for, I’m gonna test with another amp to make sure it’s actually my amp that is bad but I’m pretty sure it is because the sound doesn’t come trough the tweeter amp. I’ve tested every cap and every resistor and every diode and every inductor(even the surface mounted ones) and can not find anything faulty. The only thing I haven’t tested is the transformer(I think it is) it looks like a transformer at least, but I’ve searched the number on it and can’t find anything about it so I don’t know where,how and what the readings should be.
Hi antonkarlsen ,
Politely let us know your findings when testing another amp. The transformers are usually custom made and don’t normally fail, but you could make sure there is continuity in the windings by using continuity test or a resistance test on the lowest setting if you don’t have an auto-ranging meter. If the amp is indeed bad, it is most likely some very little part that opened up such as a chip of some kind. Some amplifiers use chip fuses instead-of or in-addition to external fuses typically marked F1, F2, etc… on the board. It is possible a chip fuse or some other small chip opened. However if they all tested good, you may want to check the solder welds, and that the board is clean (nothing spilled or no excess residue on it). It is amazing how a little excess flux on a board can render the entire amp useless from functioning.
Also there is some strange law that exists when you short out something, and it quits working, that something completely different happened simultaneously that has nothing to do with shorting out, such as the signal input line went bad, or something else not expected or remotely related. I have yet to understand this law 
Hello! Thanks for all the help but I think this is above my skill set now, I’m going to send it to professional to fix it as I’ve looked everywhere and can’t find anything wrong. I checked for fuses but couldn’t find any, neither replaceable or integrated chips. I’ve looked at every chip through a macro lens on my phone but all looks fine. I couldn’t get a hold of another amp to test so I switched the head unit instead and the noise still persists, I tried continuity testing the transformer but I don’t know which pins should have contact and which should not, and I don’t think a split second short would damage it anyway.
Thanks for helping me!
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Hi! I tested the amp earlier and found that if I don’t connect the rca’s there is no noise but as soon as I connect the rca’s the noise starts. It’s like a high pitch screech and a rhythmic popping coming through the speakers. I used a triple shielded cable and ran it far away from any power wires and the rca does not even need to be connected to the head unit to make this noise.
Hello,
You may want to check your jacks to be sure the solder joints are good also try using different cables if you have any available to see if that makes a difference.