On the Speaker's board there is a transistor or something, I cant tell because it is burned, but there is a serial saying U3 below it, what is it and is it replaceable?
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Several things can cause a transistor to burn out. Water or moisture contamination is the most common. Also, voltage spikes in the charging system,low voltage due to poor or corroded grounds or loose connections,bad solder points due to age and vibration that creates excessive resistance on the circuit board.
hot transistors are usually shorted out, or driving a short!!
a multimeter across the 3 transistor legs (TO-3 transistors have 2 legs & the case which is the 3rd leg) will reveal if they're dead (remove the transistors first as the circuit may give a false reading) - if you get a zero ohms reading between any of the legs it's dead - don't forget to check the smaller driver transistors too,, as a dead main transistor will kill its smaller driver transistor
speakers are marked,, usually 4 ohms or 8, though sometimes 16 ohms - use a multimeter to ensure you have something very close to these values according to the label on the speaker box & measure from the wires at the point where they connect to the amp
power the unit without any speakers or speaker wires connected,, if the transistors still get hot, you're very likely looking at bad transistors
you probably burnt a transistor (power supply) thats what happened to my amp if you take the cover off the bottom you can see the circuit board and there will be these little black things with three legs on them, they will probably be melted and burn marks
you will have to send it in for repairs unless you can find a shop that repairs amplifiers around you
hope this helps!!!
If you have burnt the transistors that are located on the circuit board, then you wont be able to repair it I dont think because in the circuit board there are probibly mulitple layers of electrical wires the are extremely small and fine that would make it impossible to connect the transistor to the right layer. Try contacting the manufacturer though
I assume these are the complimentary pair that drive the speakers. On one of the speaker. You know I think you have a short in the speaker that it drives. Speaker can fuction even if there was a problem with it. I think what happened is when the original transistors shorted out it overloaded the speaker, but not to a point where it is burnt. There is nothing that can overload a power transistor except the speakers, I design a lot of amplifiers, the base input can overload it if you put dc in there, but that would make a the sound all distorted, I assume the sound seem fine. Solution is try connecting a known good speaker and I bet it wont burn out anymore. Even if the speaker look fine don't trust it.
I'm not familiar with that particular amp but generally, the only transistors that burn are the ones in the power supply. If the adjacent transistors had numbers like IRFZ44, IRF3205 or similar, the burned transistor is likely the same as the ones next to it.
Confirm that the center and right-most leg of the burned transistor and the transistor next to it are directly connected by large traces on the circuit board. Also confirm that the center leg goes to the large windings of the power transformer. If it passes these tests, the transistor is one of the power supply FETs. The numbers on the adjacent (parallel connected) parts will be the same as the burned one.
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