Wiring Issue

[Spencer54]

Help me out here.

I have wire running from front to rear to power AV kit, now it was working fine.
All of a sudden its stopped working.

I can get 12v if I use a multimeter but no power to use anything.
Is it possible its corroded somewhere?

[g8dhe]

Humm, unlikely to be corroded as such, but where exactly does it terminate in the front to pickup the +12volt supply ? Is there a fuse in the added wire ? What sort of connectors are you using ?

[cmm303]

Are you measuring the 12v immediately at the AV equipment supply? In which case does it still read 12v when the AV is switched on?

[Simon Jones]

It could be a duff earth connection rather than the live that is the problem. Could also be a fault with the AV kit so try powering it from a different source to eliminate one or the other.

[Spencer54]

This is whats bugging me - earth tests OK, as I run a test lamp and it lights up - but not to that power source.

Interestingly I have a battery test meter connected and it registers as powered but really low.

[cmm303]

This is whats bugging me - earth tests OK, as I run a test lamp and it lights up - but not to that power source.

Interestingly I have a battery test meter connected and it registers as powered but really low.

If you are measuring between the positive of the load (AV or test lamp) and earth then that suggests that either the earth point isn't good (causing its voltage to rise, thus reducing the difference between it and +12v) or the 12v has a high resistance (causing it to drop volts). Eliminate which one by measuring volts between different points along the path from supply to earth.

[maxi_77]

Sounds like some form of poor connection which allows you to see the full voltage but has too high a resistance to carry current. The weirdest form of this I had was a partly blown fuse which really was difficult to find