Garmin sounder blowing fuse!

[seagulljim]

My Garmin 451s has been a good little unit and worked fine until recently.

Using a multimeter I have confirmed that a full 12 volts is getting to the unit through the pins. As soon as the unit is plugged in though (not even turned on, just plugged in), the 3 amp fuse blows .This has repeatedly happened and I have already fried quite a few fuses testing it.

The male pins on the unit as well as the female connector on the plug look undamaged and in very good condition.

Would this seem to suggest that the fault solely lies in the unit itself? If so can it be opened up and fixed? Should I be looking further into the electrics setup on the boat?

I am no expert so any troubleshooting tips would be much appreciated!

 

[GA_Boater]

Have you done any electrical work recently and the fuse started blowing afterwards?

On the input pins of the unit, check for a short between ground and the 12 volt pin. If it shows a short, something popped inside and I don't think you can much except replace it. If you get a new unit, you can do exploratory surgery.

 

[seagulljim]

Have you done any electrical work recently and the fuse started blowing afterwards?

On the input pins of the unit, check for a short between ground and the 12 volt pin. If it shows a short, something popped inside and I don't think you can much except replace it. If you get a new unit, you can do exploratory surgery.

Thank for your response. No electrical work has been done lately, although as always I have been regularly disconnecting and connecting the different leads to the battery terminals.

I set my multimeter to the ohm position and connected the black wire to the ground pin and the red to the power pin. It shows 3.3 kilo-ohms (not OL). Have I done that right? Does that demonstrate a short and that something has gone inside?

Thanks again

 

[StingrayMike]

Is there anything else connected to the unit or is it just the pwr/data cable?
Sounds like the unit is bad. When you "disconnect the leads to the battery terminals, do you mean you are actually disconnecting the factory garmin cable from the actually battery terminals? If so, could you have accidentally swapped the red and backs, even for a second??
Your meter reading doesn't show anything wrong. A short would be "zero" ohms and an open would be "OL" on the meter, That resistance is more likely just the internal circuitry, but we wont know for sure, Garmin would though.
There is nothing inside that is serviceable, unless you have some electronics knowledge to identify a bad component and the ability to change it out, so pretty much what GA said, get a new one and play operation with that one, or call Garmin and see how much they will charge to fix that one.

 

[dingbat]

I set my multimeter to the ohm position and connected the black wire to the ground pin and the red to the power pin. It shows 3.3 kilo-ohms (not OL).

No.. checking resistance doesn’t tell you a thing in a power circuit.

Set the meter to read continuity then touch the red and black pins. The meter should read open.

If you get a reading you have a short in the unit. Time for new unless you know PCB level troubleshooting

 

[seagulljim]

Is there anything else connected to the unit or is it just the pwr/data cable?
Sounds like the unit is bad. When you "disconnect the leads to the battery terminals, do you mean you are actually disconnecting the factory garmin cable from the actually battery terminals? If so, could you have accidentally swapped the red and backs, even for a second??
Your meter reading doesn't show anything wrong. A short would be "zero" ohms and an open would be "OL" on the meter, That resistance is more likely just the internal circuitry, but we wont know for sure, Garmin would though.
There is nothing inside that is serviceable, unless you have some electronics knowledge to identify a bad component and the ability to change it out, so pretty much what GA said, get a new one and play operation with that one, or call Garmin and see how much they will charge to fix that one.

Just the power/data cable is connected. I had to charge the battery out of the boat so disconnected the single power lead as well as the multiple different ground leads that come from different devices. I have done it a fair bit without issue in the past. I'm quite sure they weren't accidentally reversed.

Garmin were no help- just said I should try a third party repair place or ditch it for a new one.

Thanks for the suggestions anyway!

 

[seagulljim]

No.. checking resistance doesn’t tell you a thing in a power circuit.

Set the meter to read continuity then touch the red and black pins. The meter should read open.

If you get a reading you have a short in the unit. Time for new unless you know PCB level troubleshooting

Thanks for the clarification. I tested for continuity and it wasn't reading open loop. Came up with .185...

Sounds like confirmed short in the unit..

 

[dingbat]

Thanks for the clarification. I tested for continuity and it wasn't reading open loop. Came up with .185...

Sounds like confirmed short in the unit..

doesn’t sound right. Most meters read zero or infinity. Mine beeps on continuity.

If it where me, I would tear into it before declaring it dead. Any wire shorts would be obvious. Most likely the power supply has shorted.

 

[seagulljim]

doesn’t sound right. Most meters read zero or infinity. Mine beeps on continuity.

If it where me, I would tear into it before declaring it dead. Any wire shorts would be obvious. Most likely the power supply has shorted.

Yeah I've had it open and looking for the issues. As you can see one of the components looks a bit blackened and burst so might be the culprit. From what I hear the other culprits could be the three big capacitors. I'm not much of an expert in the area so maybe someone can help me interpret it before I throw it out once and for all..

https://photos.app.goo.gl/LMBGqLKQk7QzbrSm8


https://photos.app.goo.gl/zdYYeg1Rx7Ur6NtD9


https://photos.app.goo.gl/deNkoDQVDH3DtgQdA

 

[MTboatguy]

That cap is shot, it has shorted out and overheated causing the case to break, I would bet that is your problem right there, used to happen on computer motherboards of certain brands all the time, you will have to desolder it and get the markings off of it and put a new one in its place and pray that shorting out didn't kill something else.

 

[StingrayMike]

also if you can remove the circuit board and look at the back you might be able see any other damage. Look at the connections soldered on the back of the board and look for burnt marks between the 2 solder points.

The issue now might be being able to get the correct replacement components. If you can read the markings on top, you might be able to get a new cap.

 

[levittownnick]

Before replacing that unit I would be damn sure that the input polarity is not reversed.

 

[dingbat]

To smoke a cap like that something bad happened.

Hook the wires up backwards? Loose a voltage regulator?