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Old 01-10-2017, 06:42 PM   #1
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Default I'm test driving a Garmin 74 sv

I have an older Garmin that I'm going to replace with a Garmin 74 sv.

Before I permanently mount the Garmin (drill holes, etc.) I'm going to mount it on a clamp on Ram mount on the hand rail on my CC.

I have an extra power cord that I'd like to connect the GPS to my 12v cigarette lighter socket and plug in.

This seems almost too easy.

I figure once I get it where I can see it and access it, I'll mount it.

What am I missing? Thanks.

Last edited by Bayou Dularge; 01-10-2017 at 07:17 PM. Reason: .
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Old 01-11-2017, 05:18 AM   #2
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Not following what your are really asking, just make sure the power supply to the gps is fused correctly.
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Old 01-11-2017, 05:37 AM   #3
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Thanks. Using a fused 12 v plug - so I think I should be good.

Thanks
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Old 01-11-2017, 06:00 AM   #4
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Thanks. Using a fused 12 v plug - so I think I should be good.

Thanks
no...the outlet you are using probably uses a fuse that is rated much higher than the unit requires....if you are going to use an accessory outlet you should use the inline fuse supplied with the unit to protect it properly....or reduce the outlet protecting fuse to the proper rating....
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Old 01-11-2017, 08:36 AM   #5
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Ok, nit picky technicality here - the fuse is NOT there to protect the unit. Its there to protect the wiring going to the unit.
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Old 01-11-2017, 10:44 AM   #6
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Well the 74sv is combo unit so it has sonar as well. If you want to check sonar ability you will need to connect a compatible transducer as well. The unit I believe goes into the simulation mode if no transducer is connected. Your older Garmin transducer is most likely not compatible with the 74sv.


if you have any other NMEA0183 devices they will need to be wired up as well such as a VHF requiring GPS data via NMEA0183.


Jim
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Old 01-11-2017, 11:27 AM   #7
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Not using the sonar on mine.
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Old 01-11-2017, 11:52 AM   #8
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Ok, nit picky technicality here - the fuse is NOT there to protect the unit. Its there to protect the wiring going to the unit.
well then i would guess a lot of electronic companies would use fuses larger than 2 amps on delicate electronics as the wiring to them is capable of handling much higher amperage....

but i digress...
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Old 01-11-2017, 08:18 PM   #9
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The fuse is there to protect the wiring not the device. Looking at ohms law there is no way a fuse can protect the device. Fuses only slightly larger than the device's max current draw are used because there is no sense stressing the wiring more than necessary if the device shorts.
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Old 01-12-2017, 04:15 AM   #10
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The fuse is there to protect the wiring not the device. Looking at ohms law there is no way a fuse can protect the device. Fuses only slightly larger than the device's max current draw are used because there is no sense stressing the wiring more than necessary if the device shorts.
i understand your point but the difference between a simple board failure inside a device and a catastrophic failure is potentially the size of the fuse protecting it...it has nothing to do with ohms law...the wiring to most electronic units is heavy enough for an internal short to cause more damage than it has to if protected by the proper sized fuse....when a low voltage internal circuit becomes a high voltage circuit components may be damaged that would not have if the proper fuse was utilized...if you would like to apply ohms law, which you seem to have a fondness for, it might become clearer...
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Old 01-12-2017, 05:01 AM   #11
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Not sure what you're trying to ask, but you'll love the unit.
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Old 01-12-2017, 05:40 AM   #12
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Not sure if there's a question in there somewhere, but you'll love the sonar on it for finding winter holes in the marsh holding trout near Dularge.
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Old 01-12-2017, 07:51 AM   #13
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Gentlemen, the fuse is there to protect your electronic device/devices and wiring. The wiring must be large enough to be able to draw the current required to blow the fuse should the wire or device have a short or degradation of some kind, otherwise the wire will get hot, burn off the insulation, melt and possibly cause a fire. The fuse or breaker should be sized properly so it blows when the device draws more than normal current, this does not mean a direct short to protect the electronic device.


An example of how a fuse protects an electronic device, this is just one example.


My Garmin Radar GMR 1224 xd2 has a fuse going to the pedestal, I believe it is 7.5 amp fuse. Should the radar antenna be blocked by something preventing it from spinning up and the radar is turned on, the fuse will blow protecting the radar rotation motor, drive gears and the power supply supplying power to the radar pedestal. If the fuse was too large or did not exist the radar would be damaged and costly to repair.


Jim
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Old 01-12-2017, 04:16 PM   #14
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Quote:
Originally Posted by bladenbullet View Post
i understand your point but the difference between a simple board failure inside a device and a catastrophic failure is potentially the size of the fuse protecting it...it has nothing to do with ohms law...the wiring to most electronic units is heavy enough for an internal short to cause more damage than it has to if protected by the proper sized fuse....when a low voltage internal circuit becomes a high voltage circuit components may be damaged that would not have if the proper fuse was utilized...if you would like to apply ohms law, which you seem to have a fondness for, it might become clearer...
...when a low current internal circuit becomes a high current circuit...
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Old 01-12-2017, 04:29 PM   #15
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Originally Posted by jfwireless View Post

My Garmin Radar GMR 1224 xd2 has a fuse going to the pedestal, I believe it is 7.5 amp fuse. Should the radar antenna be blocked by something preventing it from spinning up and the radar is turned on, the fuse will blow protecting the radar rotation motor, drive gears and the power supply supplying power to the radar pedestal. If the fuse was too large or did not exist the radar would be damaged and costly to repair.


Jim
You make a fair point. I hadn't considered the possibility of a piece of electronics perhaps temporarily consuming more than it should. Still, using an inline fuse to protect against something like that seems like a dubious protection strategy on the part of the manufacturer. I can see a slow-blow fuse being used that way but that is usually part of an internal circuit and not the mains (and it usually has strict instructions associated with it). Regarding the radar motor, i would think that a built in self resetting motor protection circuit breaker (MPCB) would be better and I would be surprised if the Garmin didn't have one. Don't know.

I guess the real telltale about just what the manufacturer's expect in the way of protection is warranty coverage. Do they say warranty void if wrong fuse is used? Maybe, but I haven't seen it. Kind of the same with AC appliances. They never say only hook it up to a 15 amp circuit, never to a 20 amp one. I know that those are shared circuits but still, no implication of equipment protection there.
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Old 01-12-2017, 04:38 PM   #16
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Devices with motor circuits are very different from pure electronics. The fuse in your mfd, radio etc is there to protect the wiring - not the device.
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Old 01-12-2017, 04:40 PM   #17
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I have this unit with the transducer. It's a great piece for the money. I wish someone would discount the upgraded map though.
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Old 01-14-2017, 11:19 AM   #18
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Originally Posted by Yrral3215 View Post
Devices with motor circuits are very different from pure electronics. The fuse in your mfd, radio etc is there to protect the wiring - not the device.
I apologize for the hijack but this is the kind of misinformation that gets people in trouble....have a nice day...
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Old 01-14-2017, 11:32 AM   #19
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I apologize for the hijack but this is the kind of misinformation that gets people in trouble....have a nice day...
I agree that misinformation is bad. Here is the first one of hundreds of references that pops up for you when you do a Google search. Try looking at the ABYC Standards for marine wiring and do a little research instead of promoting old wives tails.



https://www.jamestowndistributors.co...t.do?docId=108

Quote:
What is circuit protection?

Circuit protection is the intentional installation of a "weak link" in an electrical circuit. This is a fuse or circuit breaker, referred to here as a circuit protection device or CPD.

What is the CPD protection against?

Prevention of wire conductor overheating and resultant burning of the wire insulation is the primary reason to install a fuse or circuit breaker. In some cases they are also installed to protect electrical or electronic equipment from damage.

How does fire start in an electrical circuit?

Fire results when too much amperage travels through a wire. Amperage is electron flow through a conductor. If too much amperage flows through a wire, enough heat can be generated to melt and burn the wire insulation or surrounding materials.
Yes, there are some cases where the fuse is designed to protect the device - as in motor controllers for example. However, those are the exception to the general rule.
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Old 01-14-2017, 01:52 PM   #20
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Quote:
Originally Posted by Yrral3215 View Post
I agree that misinformation is bad. Here is the first one of hundreds of references that pops up for you when you do a Google search. Try looking at the ABYC Standards for marine wiring and do a little research instead of promoting old wives tails.



https://www.jamestowndistributors.co...t.do?docId=108



Yes, there are some cases where the fuse is designed to protect the device - as in motor controllers for example. However, those are the exception to the general rule.
I guess the second half of the paragraph wasn't worth highlighting...lol...

of course wiring needs to be protected,....but delicate circuits in electronic equipment need protection also...
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