Question Speaker crossover failure

nigelk1

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Hi,
The crossover in one of my speakers appears to have failed and I’m having trouble diagnosing what is actually at fault.

The symptom is a very small sound initially and then nothing. I’ve swapped the crossover from another speaker and everything works ok, so it appears to be the crossover.

The resistors have test ok with a multimeter, but I’m not sure what the yellow things are. I’m assuming capacitors but they don’t have farad information on them, they are something like 42.0j 100v or 18.0 j 100v and I don’t know what this means.

Can anyone help please ?
 

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The capacitor values are likely to be in uF and will be non polarised capacitors.

I would start by checking for dry joints and re-flow every joint on the board before you start swapping out capacitors.
 
The capacitor values are likely to be in uF and will be non polarised capacitors.

I would start by checking for dry joints and re-flow every joint on the board before you start swapping out capacitors.
 
OK thanks. I will give that a go first.
 
It didn’t appear to make any difference, I’m still not getting any output.
 

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Have you tried a volt meter to check continuaty from both ends of each of the caps ? I had the same issue with some old missions and the culprit was a dead cap.
 
Depending upon the voltmeter, you should set it to a low Ohms range and then when you measure across the capacitor you should see a low resistance that then rises over a few seconds.
 
Thanks guys, i had been reading up on testing capacitors. I only have a basic meter, see pic, but will give it a go. I had a go at drawing a schematic from the board, which I think looks like this.

I will see how the testing goes, and will compare to another which I know is working.
 

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I had a go at testing them this morning and it wasn’t very successful.

The 18.0 one gave an expected response but I didn’t get anything really from the others. The only difference when I checked a working one was that I also got a response from 20.0 one also.

I suppose this could mean that I’m checking them wrong, or they are all broken.

I set my meter to ohms In auto mode for the test.
 
With a capacitance meter it's always a bit hit and miss. Worth checking the inductors (coils) as well.

The capacitors will not normally be applied to the bass speaker, only the mid and hf drivers, so I would expect the bass speaker to still work even if the capacitors had failed.

Have you checked the switch is working correctly?
 
The inductors have continuity and some small resistance level which is expected, there is no labelling though so not sure exactly what to be looking for on these.
I’ve found out from another forum that the J means a tolerance of +/- 5% .

The switch is a weird one, it seems to have continuity in either position so I’m still working on this.

I’ve corrected my diagram so here’s a new version.

I have mid range and high range drivers in the box, 2 of each
 

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From the looks of that, even if all the capacitors were open circuit you would still get audio through the mid / bass speakers. The soldering around the 4 pin connector in the middle of the board looks a little suspect. I would be tempted to de-solder this, clean up the connector and re-solder.

You are looking for any common components if there's no sound - and there's very few of those, just the switch and an inductor or 2.
 
Good point, there should be something coming across that switch no matter which position it’s in, through the inductor to the speaker. So the connector is a good bet.

I’ll test the connectivity through it first.
 
I did some more checking and resoldering, and it appears to be working now. Not sure what was actually stopping it from working, but I will keep an eye on it.

Thanks for all of your help, it was very useful.

Nigel
 

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