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View Full Version : How to wire new head unit


ricford
07-18-2012, 11:24 PM
Finally bought a new head unit for my boat: Kenwood KMR-700U. The old Clarion that came with the boat hasn't worked since I bought the boat. I'm very happy with the unit but, just curious how you guys wire the power to the head unit. There are 2 "power" connections, one that connects to the battery to hold presets and clock settings, and the other that is supposed to connect to the ignition so that the head unit shuts off with the ignition. I find this annoying when skiing or riding because the engine is constantly being shut off and restarted when changing riders, etc and the tunes stop. I'm thinking of connecting directly to the battery. What do all you audiofiles do? The only downside I can think of is when my 19 year old son forgets to shut it off and drains the battery.

swatguy
07-18-2012, 11:46 PM
You can wire it its own accessory switch....... this way it can give the constant power with the key off.

ricford
07-19-2012, 07:52 AM
I thought of that, but it doesn't really gain anything. You still have to remember to shut it off when you're done. I was just wondering if anyone else wires it that way.

mzimme
07-19-2012, 08:22 AM
I thought of that, but it doesn't really gain anything. You still have to remember to shut it off when you're done. I was just wondering if anyone else wires it that way.

I just did a search on some auto shutdown relays and came across this site:

http://www.curioustech.net/timers.html

You might email greg and tell him you want a timer to cut power at whatever number hours you think would be appropriate. I would think a 4-5 hour timer on that relay wouldn't interrupt your listening time unless you're coved out with the radio on for a long time. It also wouldn't kill the battery in 4 hours just running a head unit in the event that you forget to turn it off. Also make sure you mention your application, as it looks like the highest power output is 6amps, and that won't be enough for a head unit. You'll probably want 10-15amp power output (if they can make that happen).

Do you run any amplifiers, or does the head unit power all of your speakers in the boat?

Looks like it could be a pretty useful solution if they can customize that to your needs.

mzimme
07-19-2012, 08:28 AM
Actually thinking about a relay more, you could just wire the head unit up per the instructions (to shut off when the key shuts off), but wire a timer into that circuit, so the radio stays on for an additonal 20-25 minutes before the timer relay shuts it off. You'd be able to turn your key off, and have the radio stay on while you switch riders.

That's probably the best way to wire something like that up.

ricford
07-19-2012, 09:42 AM
Actually thinking about a relay more, you could just wire the head unit up per the instructions (to shut off when the key shuts off), but wire a timer into that circuit, so the radio stays on for an additonal 20-25 minutes before the timer relay shuts it off. You'd be able to turn your key off, and have the radio stay on while you switch riders.

That's probably the best way to wire something like that up.

Excellent idea! You'd think, being an electrician I might have thought of that myself. I will investigate 12V timer relays. Thanks.

ricford
07-19-2012, 09:49 AM
In answer to your first question, yes I am running an amp and a powered subwoofer, but they are controlled by the blue wire from the head unit, so if I shut down the head unit they shut off as well. I think the timer relay is the way to go. If I'm lucky I might even be able to find one laying around at work.

mzimme
07-19-2012, 12:50 PM
Another idea would be to get a new ignition switch that has Off-acc-on toggles, rather than just off/on.

ricford
07-19-2012, 09:49 PM
It has an acc position, but it shuts off in between no matter how fast you turn the key, and then it takes about 15 seconds to reconnect to the ipod or memory stick.

charrison327
07-10-2013, 04:15 PM
it's great to find old thread with suggestions. i installed a new head unit today and wired to an acc that was not being used per swatguys recommendation..... i was tired of it not keeping memory also. when i turned it off for people to ski or board, i would turn it real fast. there was a slight pause, but it would keep memory. however, if i turned it off for a while i would have to reset everything. works like a charm now

ricford
07-10-2013, 05:43 PM
Glad it helped you out. I haven't done the relay thing yet, but I did wire it directly to 12V. Just have to remember to shut it off. Haven't drained the battery yet.

73blue
07-10-2013, 06:13 PM
My new Sony head unit has a timer you can set to turn off after so many minutes of inactivity (changing stations, volume, etc)

charrison327
07-10-2013, 06:27 PM
yeah, i think mine does too. i remember seeing something about it in the manual as i glanced through it. it's a sony also, but can't remember the model off the top of my head.