USB failure

[Rod]

I'm after some guidance after the usb in the motorhome stopped working.

I can't find a blown fuse and everything else is working.
Before I cut it out and replace it I am trying to confirm it has power.

I have checked across the black and red wires by using a pin and exposing a little wire and get 1v.

Checking the earth to another socket gives full continuity with a continuous alarm.

Checking the live to another live socket gives a bleep on the alarm and a reading of 800. Testing on ohms for a complete circuit.

It looks like the cables are still okay but what would only give me a 1v reading.

Any advice welcome.

Thanks Rod

 

[trevskoda]

May be a brake in the pos line, bad connection fuse etc, try running a pos wire from a fuse to unit and see if that gets it running.

 

[ProDave]

USB is 5V. the van is 12V. So each USB socket will contain it's own voltage regulator.

Post some pictures, it is unclear what you are measuring. There must be more than one USB socket in the van. Are all dead or just this one.

 

[Rod]

USB is 5V. the van is 12V. So each USB socket will contain it's own voltage regulator.

Post some pictures, it is unclear what you are measuring. There must be more than one USB socket in the van. Are all dead or just this one.

It's only this socket that's not working

I've measured the voltage across the wires in the back of the socket as described above.

 

[trevskoda]

It's only this socket that's not working

I've measured the voltage across the wires in the back of the socket as described above.

Thats from the stoneage and a low powered unit, ebay has replacements with higher amp outputs

 

[ProDave]

It's only this socket that's not working

I've measured the voltage across the wires in the back of the socket as described above.

So the wires connecting to the back are the 12V in. If those are only reading 1V then there is an issue with the wiring feeding it. A blown fuse or failed connection somewhere. A case of follow the wiring and see where it goes and what it connects to.

You could take the whole socket off and test it elsewhere, I would do that by feeding it from a bench power supply set to 12V

 

[MERL]

If you're reading 800Ω between the positive of one socket and the positive on the other then you've got a high resistance connection somewhere in the positive supply to the socket, almost certainly a corroded contact. Tracing cable runs can be almost impossible sometimes, if so your best bet is to find another 12v positive nearby and run another supply cable to the socket.