Weird fuse problem - keeps blowing - scratching my head here...

**gthing** · 08-21-2007, 04:05 AM

So today while on a road trip, my carputer suddenly shut down and everything went dead, including my in dash clock. Simple enough - it's a fuse, right?

Sure enough, a 15a fuse in my fuse box had blown - this is the one that controls the stereo and goes to my carputer. It is a mac mini being run off of a Carnetix p1900 power supply.

I replaced the fuse, only to have it blow again after about 30 seconds. I tried several different things to try to narrow down the problem and burned through about 4 fuses before just scratching my head and giving up.

The fuses don't blow immediately, but always within the first 30 seconds. Does anyone have any common troubleshooting ideas or tips to help me figure out what's wrong?

**pate60** · 08-21-2007, 05:14 AM

your probably drawing too much current... i am assuming your running your computer off this fuse as well if so... try leaving the stereo off, when using the pc and vice viser then try it and see if it still occurs.

if that is the way you've wired your system, it would be best to run new cabling specifically for the computer.

**DarquePervert** · 08-21-2007, 07:34 AM

Yup. Your PC, stereo & clock are drawing more than 15a of current, causing the fuse to blow.
The fuse is doing its job by blowing.

I agree that you need to wire your computer to another circuit, preferably one that powers ONLY the PC.

**gthing** · 08-21-2007, 07:18 PM

I don't have a stereo - only my computer and my touch screen, and only the computer is on the stereo circuit (so, it is on its own).

I know a blown fuse means that there is too much current, but the problem is that is has worked fine for a year and now all the sudden it blows fuses after 30 seconds - I can't figure it out.

**RedGTiVR6** · 08-21-2007, 07:31 PM

you have a short somewhere.

a nicked wire or loose ground, etc.

**parksgm** · 08-21-2007, 08:27 PM

Originally Posted by RedGTiVR6

you have a short somewhere.

Yep...unless you changed something else on the system, a short is the most likely culprit.

The fuse probably takes some time to blow because you are not exceeding the 15A rating by much, inclusive of the short, and the result is that the fuse S L O W L Y O V E R H E A T S and melts...resulting in the delay you are experiencing.

**Pokey** · 08-25-2007, 11:17 AM

A couple of things you might check..

the guage of the wire being used to power the computer, the smaller the wire the more resistance, more resisitance, greater voltage drop on the wire, meaning your computer is not getting enough voltage, thereby making the computer ps to draw more current to makeup for the lack of voltage. Personally I use 7ga...

add up all your devices, harddrive, video card, etc.,etc.. current requirements.. might be that you are right at the limit of your fuse.. go a fuse higher. If you have access to a ampmeter, throw that in series with your fuse and see exactly what you system is pulling.

And, it might be that you're getting into the summer time and your fan is working overtime...

I would check it with a ampmeter to see where you stand.. make sure it can read more than you're measuring, or you will blow the fuse in the meter..

Good Luck