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Old 12-26-2002, 08:59 PM
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On my new radio (mc402) the power supply has a red and a black wire,which one is for the positive terminal? The red wire has a in line fuse. Thanks Bobby [img]/infopop/emoticons/icon_confused.gif[/img]
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Old 12-26-2002, 10:26 PM
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On a power supply, red always denotes positive. Typically the fuse is only on the positive wire, although I've seen fuses on negative wires too.
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Old 12-27-2002, 05:44 AM
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Red is positive, usually the fuse is inline. [img]/infopop/emoticons/icon_wink.gif[/img]

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Old 12-27-2002, 05:51 AM
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I am sorry and I mean no disrespect, but if you are unsure of black & red power leads with an in-line fuse on one, then perhaps you should not be attempting electronics installations on your boat.
That said the above was correct. I hope you are not thinking of cutting the antenna cable or putting on your own PL259. Your radio is important. Installation is one thing, working correctly is another.
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Old 12-27-2002, 06:15 AM
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Tides, This would be true for positive systems but not for a negative systems. In telecom we use -48 volts for all our equipment and red means negative. [img]/infopop/emoticons/icon_biggrin.gif[/img]
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Old 12-27-2002, 07:47 AM
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Never say 'always' or is it: never say 'never'. Med66, let's 'ass-u-me' the system is a 12v positive ground system! [img]/infopop/emoticons/icon_razz.gif[/img] [img]/infopop/emoticons/icon_biggrin.gif[/img]

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Old 12-27-2002, 08:56 AM
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Yes, I was assuming all power supplies in question were positive.

[This message was edited by TidesHHI on 12-27-02 at 02:15 PM.]
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Old 12-27-2002, 10:25 AM
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Tides, I was talking about positive and negative ground systems. You will have positive and negative connections, but it is wired in reverse of a positive system thus having a - 48 volts instead of a positive 48 volts. Almost all telecom equipment is -48 volts. [img]/infopop/emoticons/icon_wink.gif[/img]

We had a master electrician working on converter from -48 volts to 110V. He kept on telling my boss that the system did not work. I went over and looked at how he had it wired and found he had the red in the positive and the black in the negative. I told him to reverse the cables and he refused, he told me I was going to damage the equipment. I took a screwdriver and changed it myself and the unit started working.
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Old 12-27-2002, 11:14 AM
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I know how to do simple electrical work. [img]/infopop/emoticons/icon_wink.gif[/img]
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Old 12-27-2002, 12:05 PM
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Thanks for the info. Bobby [img]/infopop/emoticons/icon_smile.gif[/img]
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Old 12-27-2002, 01:29 PM
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Bobby,
I'm suprised Thon didn't chime in yet, but here's something I saw him post once that makes sense.

Remove the in line fuse and fuse the radio only once (where its connected). Usually this will be a fuse block. I also recommend keeping the terminals as dry as possible by putting all connections and terminal blocks in a small plastic box. You can get one at Home Depot or make your own like I did from starboard. Do not splice anything (use terminal blocks and ring connectors).

I have been doing things this way for about six years and have yet to have 1 electrical problem. Before this I had butt connectors corrode and terminal blocks stop conducting due to a suprisingly small amount of corrosion. Keep all connections in a box! [img]/infopop/emoticons/icon_wink.gif[/img]

Sea Ya,
Scott
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