I installed a sony stereo into my 97 Integra and I keep blowing the 7.5 amp fuse under the hood labeled as backup. I figured I would replace it with a 20 amp fuse since 12v x 20amp = 240w and I have a 200w stereo it would give me an extra 20w to work with. Ten seconds later the fuse blew. Suggestions?

 

The fuse blows because the load is too high.

NEVER replace fuses with bigger ones, you can burn your car to the ground.

The wiring in the stock radio harness/plug can not supply the current needed by "high power" aftermarket HUs, the fuse is there to protect the wire installing a bigger fuse can at the very least damage the wiring harness, and at worst, kill you.

Treat your HU as an off-board amp, run a power wire to it, run a 12-10 gauge fused lead from batt. to behind the HU, connect the HUs 12V constant, [yellow] to it, don't forget to cap off the now unused stock 12V constant, and replace the fuse with the proper 7.5A one.

The 12V switched lead, [red] and illumination leads, [orange and orange white] if your HU has them, along with the ground, [black] can stay connected to the stock radio harness, if the HU is not connected to the metal dash sub-frame with a metal back brace, [or ISO mounts] as it should be, add a 12ga ground strap from the chassis of the HU to the chassis, [dash sub frame] of the car.

You will notice an improvement in SQ and even SPL, the HU will run cooler, and you will not be blowing fuses or burning wiring harnesses. 94

 

I replaced my 7.5amp with a 10amp and then a 20amp. After blowing the 20amp, I replaced it with another 7.5amp and its still working. The HU is a 200w peak. Im assuming when you say to run a fused lead, you want me to run a wire with a fuse as an intermediary. This is a replacement for a stolen deck. I dont have any kind of a system and I don't think the amount of work you are suggesting is actually required. Why would I have to run a fused lead if there is already a constant 12v power wire supplied directly into the harness? Im not trying to be a jerk, just trying to understand.

 

The stock 12V constant and the ground can not supply the current, [amps] needed by the aftermarket HU, the wiring was designed to supply current to a stock HU, [less then 2x7W RMS], your HU is probably around 4x17W RMS, a lot more current is needed to properly power the HUs internal 4ch amp then can be supplied by the stock wiring.

It's really not that hard or very much work to run the fused power lead from the batt. to behind the HU, the results are worth it, but that's up to you, it's your car and your, just don't replace fuses with bigger ones, that's a no no. 94

 

I ran a fuseable link and found out that the reason I kept blowing fuses is because the electrical tape I used somehow got undone and wires were crossing. Thanks for the help.

 

You got lucky you didn't set something on fire with that 20 amp fuse during those 10 seconds.

 

Thanks a billion for the info.