12V Radio Help

[ice_it_06]

Will reversed polarity take out a stereo ?

I had installed a car system in my sons house and was working fine off the deep cycle direct.

There is a 12V receptacle under the cabinet I installed the stereo. Upon plugging any other 12v product this receptacle worked just fine (ie vacume, lights)When I inserted the wires for the stereo it "blew" the 3amp fuse for the illimination to the deck and also appeared to have taken the power lead out as well.

I replaced the (3) amp fuse to the illumination line and I have nothing ?

I then took apart the deck to see if it had a "inline" fuse inside I might have blown but it did not.

The receptacle still works with everything else and I can reverse the plugs even on anything else.

Is a 12V car system different to where the wiring is not the same? It appears I blew the deck out which will not sit well with the kid or my pocket book.

I was trying to wire it inline to the receptacle just a foot from the deck instead of eight feet away to the battery.

[Whoaru99]

It sure can if the fuse doesn't blow first.

Polarity sensitive devices, like stereos, TVs, depth finders, etc. often have a diode across the power leads (inside the unit) that essentially causes a short circuit if the leads are connected backwards. This assumes there is a correctly sized fuse or circuit breaker to blow before the diode, other electronic tidbits, or the wires melt.

I understand the lights working, they are not polarity sensitive, but I'll be the vacuum cleaner ran, but ran backwards and wouldn't have vacuumed very well.

It almost sounds like there was no fuse in the power lead so something else had to blow/melt and that something sounds like the radio in this case.

You need to check the polarity of the receptacle before plugging any more stuff in or reversing the leads for a test. If it's the cigarette lighter style of plug, proper polarity is positive (+) on the center post/pin/contact, and negative (-) on the outer sleeve/shell/contact.

[ice_it_06]

Your assumptions are correct on two levels. The Radio did not have a fuse in line, and the vacume ran muuch better with the plug turned opposite of first attempt.

This house is used and prewired with all 12v items having older normal household plugs on all the lines. Nothing is marked on any plug or receptacle for connection.

I was going to put in a 12v cigarette plug in the receptacle. I should have removed the face plate and made sure the hot was to white and the neg to black. Then put in a fuse to the hot line which I'm sure is what blew the deck seeing it did not even power up the face after the illumination fuse blew!!

Thanks for your tip on the plug connection as I'll be putting in the 12v cigarette plug just for the new $180.00 unit of the kids I just trashed. I'll fuse it as well as having the dedicated plug.