Can I test speakers with a multimeter, and if so what sort of reading would I be looking for. I have a speaker which started to crackle and now stopped working, I can access the speaker to test it if I cannot get a reading from the back of the radio. I just want to eliminate a faulty speaker from the wiring. Swapping speakers will not be as easy.
TIA
Perhaps, but considering your reason it may be an intermittent fault that will intermit itself away the moment it sees the test leads.
A resistance somewhere from 4 to 16 ohms is usual. Probably marked on the back. Certainly not zero or nigh-on infinite.
Get a little transistor radio and connect its speaker in parallel with the one in the car. Don't turn up the volume very far unless you want to set the radio's magic smoke free. If it still crackles/stays silent the speaker may well be faulty. If it sounds fine (if perhaps a little on the quiet side, considering what you're asking a little radio to do) then the speaker is good.
Andrew
Now it's stopped working, well...if the speaker is the culprit, your multimeter should give an 'infinitely large resistance' reading, i.e.open circuit.
You don't have to take out and test the speaker directly. If the *output from the radio* connected to a known working loudspeaker is sound ( :)) then you can assume the original speaker is defective. Alternatively, wire up a known working portable radio to the *input leads of this speaker*; even if there is a mismatch of input impedance, if the speaker is OK, you can still get some sound without crackles.
Er.. wrong, surely? You can assume that either the speaker or the wiring is defective.
Step after that is to test the speaker itself - then if that's ok, it's the wiring. Which would be quite high up my list of suspects.
cheers, clive
Probably a bit lower, as it's an inductive load, but certainly a bit more than zero, and below 20 ohms. You should hear a click from the speaker as you connect the meter, though it may be faint.
Single driver speakers usually have a DC resistance pretty close to their nominal impedance. The wire and connectors will add some. So something like 6 ohms would be typical for the whole circuit. A burnt out speaker or wiring will read near infinity - 10s of thousands of ohms. Sometimes a speaker can be damaged physically so it still gives a correct DC reading. but produces little or no audio.
And since when did inductance have an effect on the DC coming from a multimeter? ;-)
Andrew
"Thanks for the tips, I am pretty sure I will be able to diagnose the fault now.
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