USB input on stereo won’t work

[WICKER55]

I have just installed a new stereo in my aluminum boat. The stereo works great when the boat is sitting in the driveway on all inputs (tuner, USB-I use the USB a lot). When I put the boat in the water and turn on the stereo the USB input drops out and will not play. The radio still Works but not USB. I thought maybe the outboard was interfering with stereo so I wired the stereo to a dedicated battery but go the same result. Has anyOne experienced this before and know how I might address it?

 

[Alumarine]

Doesn't make sense that it works in the driveway only.
Does it work in the water with the motor not running?
Where is the ground going from the stereo?
Have you contacted the stereo manufacturer?

 

[WICKER55]

That’s a good question. I had already planned to check that the next time I take it out, I figured someone would ask. Think tomorrow will I will go. Anything else I might check? The ground from the stereo is going directly back to The negative post on the dedicated battery that the stereo is fed from. I tried talking to manufacturer but they were no help.

 

[WICKER55]

I took the boat out yesterday. Started stereo when boat was on the trailer, launched it and USB tunes were still playing. As soon as I started outboard the USB dropped out.

 

[Alumarine]

Why not tell us what motor?
If it's unregulated maybe it's putting out too much voltage?
Have you checked the volts when the motor is running?
When you say dedicated battery do you mean the stereo is connected to a standalone battery that is not connected to the boat electrics in any way?

 

[dingbat]

I tried talking to manufacturer but they were no help.

Because the symptoms make no sense.
The 12vdc to the radio simply feeds the Internal power supply that reduces the voltage to component level requirements. The USB port is powered from the internal power supply. In theory, if the radio works the usb should.

Need to eliminate a few variables:
1. Does the port work with the motor runnng on the trailer?
2. Does the port work on the water with the engine off?
3. How many ohms from radio’s chassis ground to the battery
4. Voltage at the radio with the motor running?
​​​​​​

 

[WICKER55]

Think I figured it out. Last time I launched the boat the ignition switch would not start the motor. The key actually turned right around. After installing a new ignition switch And replacing the 20 amp fuse under the cowl the motor started fine and the USB feed to the stereo worked Even with the motor running. I figure it must have been some sort of interference from the bad ignition switch which affected the stereo. Anyway, thanks for your help.