Sub is blowing fuses!! :(
My basslink sub stopped working a few months back. There was no power at all. I decided to troubleshoot it today and found a blown fuse. I went to the store and picked up another 20A blade fuse. The sub finally powered on. However there was still no audio. The power LED was solid and the Servo LED would fade in and out gradually. 5 second fade in, 5 second fade out, approx. I unplugged everything and plugged it all back in and bam. No power. Checked the fuse and it was blown. What's the most likely reason that this would happen?
Car Audio & Video - Infinity - BASSLINK Car Subwoofer
Answers & Comments
The issue is most likely a short in the amp internal circutry where power is essentially flowing without resistance acrosss the short. You may or may not have sound or crackling noise as it depends on where the short is.
If you are electronically inclined, I suggest the folliowing:
- disconnect all power and open the amp up
- look for any burn marks around the circut board and parts.
- first focus in on the area where the power comes in - see if any diodes (black cylinders with stripes on them) are burnt / cracked
- next have a look at all the MOSFETS. These should be 3-legged components and will likely be mounted to the shell or heatsink. Look for any burn marks or cracks on these.
- also look for any wire or component that may be shorting other components. Generally all wires should have shielding and all components should be soldered firmly. Anything crossing other components could be a problem.
If you find any burnt/cracked components, they will need to be replaced.
Here is a sample image showing the MOSFET chips to the top and bottom on the aluminum rail.
http://memimage.cardomain.com/ride_images/3/2514/3981/31284490262_large.jpg
Its hard to tell from the images what the charred piece is - but looking at the area, Id say its in the power supply now. You have to pinpoint the burnt components. It could be as easy as finding the parts and replacing them. I think the reason why you get 30 seconds of life is because the charred component is shorted, but not completely. Essentially, its like a half broken dam, water is rushing out, but not all at once. If it were all at once, the fuse would blow immediately.
The capacitor in my amp blew in the same place, could be an increase in current caused by a bad amp transister.
I'm gonna put a larger voltage rated 1000uf capacitor @ 200 volts and repair the burnt circuit board trace that was vaporized. If the problems persist then it's most likely a bad power transister.