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Old Yesterday, 02:20 AM   #1
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Join Date: Jul 2014
Default Audiobahn amp turns on briefly and turns off

I have an Audiobahn A8000T amp. A co-worker told me it could be the diode, so I replaced that, and tested it. It didn't change the results and the MOSFETs would actually catch fire. I noticed a few cracked afterwards and replaced them. Now, the amp will turn on (no more fire ) but it will only stay on for a second or two. It doesn't go into protect mode, it lights up, and the fan starts rotating, only for those few seconds though. Any thoughts on this?

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I replaced all 8 of these MOSFETS on the board.
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Old Yesterday, 02:56 AM   #2
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Test the output transistors to see if they are shorted. When they short they will fry the transformer section. If they are shorted work back through the amp section to see what else failed. Sometimes they take the drivers with them.
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Old Yesterday, 10:56 AM   #3
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Location: Dona paula, Goa
Check the output dc offset of the amp. Connect the DVM and then, power it ON.

Gajanan Phadte
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Old Yesterday, 03:06 PM   #4
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Quote:
Originally Posted by gmphadte View Post
Check the output dc offset of the amp. Connect the DVM and then, power it ON.

Gajanan Phadte
In my experience it's not a good idea to power up a car amp when it's shutting itself down. They quickly destroy themselves. I usually test output transistors for shorts with no power applied first. Usually larger amps like this are driving subwoofers and the outputs fail hard from the heat.
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Old Today, 05:39 AM   #5
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Are you sure you want to go pulling components one by one for cold testing.

Best of luck.

Gajanan Phadte
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Old Today, 09:32 AM   #6
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No need to remove anything to test for a shorted output. Quick test with an ohm meter.
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