Question about Nitro BMW-482 Car Audio Amplifier
I took out my subs in December and left the amp
and wiring as is. Two days ago I went to put my subs back in and the
amp would not turn on. There was a blown fuse. I replaced the fuse but
the amp blew the new one in two seconds.
I have, since then, taken the amp out of the car, hooked up brand new wires directly to the battery (positive battery terminal to positive input, amp ground to the negative battery terminal), ran a new remote wire and removed all other inputs and outputs from the amp (ie. No RCA inputs from the deck and no speaker load or wires to the subs). It is now an amp with three wires. A power, a remote, and a ground.
The amp STILL blows fuses.
I have taken it apart today. I'm definitely not an electrical engineer; although I wish I knew one. I am looking to see if anything appears out of the ordinary - nothing does. All components look pristine, in tact, and well maintained. There is a circular donut with black, red, and copper coloured wires wrapped around it (all those wires are copper - about 18-20 gauge) I don't know what this is or how to check if it is the problem.
There is a coil with a thick black stick inside of it about an inch long. I don't know what this is, what it does, or how to test if it is working.
Basically, my question is, with this set of symptoms, can anyone come up with a reasonable diagnosis? If the amp is blown, that's fine, but it worked when I uninstalled the speakers in December. So, what could have possibly happened since then to blow the amp? There was no load on it.
Anyway, thanks in advance for the help!
Additional Details 2 minutes ago Model is:
BMW-482 2Ch MOSFET Bridgeable Amplifier
Serial No. 100420199
It turns on for two seconds and seems to be "working" until the fuse blows. Originally when the subs were still connected, it gave the "puh" sound when the power first turns on. This was normal for the three years that I had the amp running perfectly.
I didn't push it to its max either. I never turned it up very loud.
It probably has shorted output transistors.If it's like many of the Asian amplifiers, the outputs will be larger than the rest of the devices clamped to the heatsink. If you measure the resistance between the legs of any individual output transistor and read anything near 0 ohms, the transistor or one in parallel with it is likely shorted and will need to be replaced. You'd have to remove it from the board for definitive testing.
The donut is a power transformer. The coil with the black stick is an inductor.
The following page will help acquaint you with the components inside the amplifier.
Amplifier Repair Primer
Posted on Aug 15, 2008
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