adding mobile sound to a boat/Old Mercrusier with Single reset fuse

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rocket1968

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Feb 18, 2008
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I am adding some audio equipment to a boat with a 1974 Mercruiser 165 and all I see for a fuse is the single red reset button on the top of the engine. Is this the catch all for all circuits? I am very good at mobile electronics but this is sort of a stumper. I am leaning towards adding a fuse box off of the battery and then a remote switch to power this box up.
 
U

Uraijit

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Re: adding mobile sound to a boat/Old Mercrusier with Single reset fuse

Can't help you find the fuse box, but if indeed, there is no fuse panel on this boat (seems like a long shot), I would add a fuse panel, and power it with a relay off the ignition, rather than just using a switch.
 
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wakeboarddude

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May 21, 2007
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Re: adding mobile sound to a boat/Old Mercrusier with Single reset fuse

What type of sound equipment, like a stereo? I have an aftermarket car deck in mine and i just run power directly from the battery with an in-line fuse and a master toggle near the headunit. Very simple and cheap.
 
ziggy

ziggy

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Re: adding mobile sound to a boat/Old Mercrusier with Single reset fuse

Is this the catch all for all circuits?
Click to expand...
i ain't the pro at electrcity thats for sure. but i'm gonna say yes to that question. hope someone who knows for a fact will answer..... best i can see in lookin at the wireing diagram for my 75 w/ indicator light, that 40A breaker is the only circut protection. it leads to the ammeter... which best i can see powers up everything else on the dash. for switched, fused power. apperenty ya take it off the back of the ammeter on the switched side. the red/white wires. has two of them on that terminal. load not to exceed 35A. pick up ground off the back of the ammeter too. that's my speculation..... service manual #2 has the wireing dia. i refered to.

myself... i did like others are saying. i ran two wires from the batt. up to the dash... fused at the batt. i put in a 6 fuse aftermarket panal from here on iboats as i had more than just a radio i wanted to power up. yes, this is non switched power....
 
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wakeboarddude

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Re: adding mobile sound to a boat/Old Mercrusier with Single reset fuse

ziggy said:
myself... i did like others are saying. i ran two wires from the batt. up to the dash... fused at the batt. i put in a 6 fuse aftermarket panal from here on iboats as i had more than just a radio i wanted to power up. yes, this is non switched power....
Click to expand...

I originally had this set up but my stereo would cut out at higher volumes. Someone told me it was a poor ground. I replaced everything and changed over to grounding the stereo to the block, now no problems. And still super simple.
 
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heyttown

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Re: adding mobile sound to a boat/Old Mercrusier with Single reset fuse

If your just running a new head unit, I would run straight from the battery and have a small inline switch and fuse to kill power to the head unit...If your running amps and multiple speakers I would run a fuse block just for the audio equipment....I normally fuse each amp individually,plus an inline fuse for the head unit.
 
Bondo

Bondo

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Re: adding mobile sound to a boat/Old Mercrusier with Single reset fuse

Ayuh,.....

There Shoud be a fuse block up by the helm, maybe somewhere Under the dash.......
 
ziggy

ziggy

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Re: adding mobile sound to a boat/Old Mercrusier with Single reset fuse

There Shoud be a fuse block up by the helm
Click to expand...
that's what ya'd think would be the case. that's for sure......
however i've not been able to locate a fuse block on either my 72 or 75 boats. both 165 mercruisers.... i aslo don't see any fuse's or fuse blocks in the wireing diagram.... i will admit. i remember seeing at least one inline fuse holder in the wireing on my 72 trisonic.... what it was for i can't remember......

Someone told me it was a poor ground. I replaced everything and changed over to grounding the stereo to the block,
Click to expand...
that's what one of the wires i ran goes too. ground is from block to fuse panel, stereo grounded to fuse panel. 2 connections.... believe i used 8 awg wire from the run......
 
Don S

Don S

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Re: adding mobile sound to a boat/Old Mercrusier with Single reset fuse

Moving to Electrics, Electronics and Trolling Motors (not engine)
 
tashasdaddy

tashasdaddy

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achris

achris

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Re: adding mobile sound to a boat/Old Mercrusier with Single reset fuse

I have a policy when adding electrics to boats... Engine electrics and 'other' electrics should NEVER be mixed. I know that Merc say that accessories, up to 35A, can be run from the instrument panel.. Bad idea! keep the engine separate, that way if (when) you have a problem in the future you have already halved the area to start looking in. It's also much neater. That adds to reliability and ease in fault finding. What I do is to run a pair of 6mm cables to the dash, one red the other black, for obvious reasons. Get a red junction box and a black junction box.... you can see where this is going.

The big red reset button on the engine is just that, a reset button. If you get an electric short, the breaker will pop. that button will reset it. If you haven't fixed the problem, it will just pop again. Yes, it is on the main positive feed to the engine. Another good reason to keep engine electrics separate. You don't want a shorted radio killing off your power to get home!

Chris.............
 
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