8 replies to this topic

[Loco69]

Hi I'm putting my car back together and have started work on the dashboard however the voltmeter keeps blowing fuses I'm guessing it's faulty I did do lots of grinding near it soon wondering if some filings have got into it.

It's a smiths gauge with a +ve feed coming from number 2 blade on the fuse box and another wire running to earth.

Any ideas would be appreciated

Thanks

Andy

[slidehammer]

What about putting a multi meter on it to see if +ve is going to earth (ie a short circuit). Whist the grinding might have put filings in there they are quite well sealed if the bulb holder is fitted.

[Loco69]

How do I do that test with a multimeter

[smurfomatic]

Set the multimeter to resistance (often there's an option which beeps when it detects zero resistance) and connect it to the terminals.

[Loco69]

So if I get a beep when connecting the two terminals the gauge is ok?

[slidehammer]

No the gauge should have internal resistance, so should show some resistance (in the internal windings) not a straight short to earth.

[Loco69]

Ok thanks I understand what I'm looking for now

[KernowCooper]

Put one probe on the + terminal of the smiths and the other on the body with the meter on Ohms the meter should read "0" indicating no circuit to earth. Check the smiths meter has the fibre washers under the terminals as this would cause a short if missing/split

[xrocketengineer]

An ideal (theoretical) voltmeter should have infinite resistance. On the other hand an ideal ammeter should have no resistance at all. Neither case happens in real life but it comes close.