Prodigy still making popping sounds, help

[18000rpm]

My Prodigy is making popping sounds:



It was working fine but the panels were dull, so I had the panels replaced. That took about 3-4 months and during that time the speaker was not used.

After replacing with new panels (by the local dealer) the pops started happening on one of the speakers.

So far we have replaced the transformer and power supply with brand new replacements from ML. I have also swapped the panels between the speakers and the popping stayed with the speaker so the problem is not with the panel. I have also cleaned the panel connectors using contact cleaner. Also checked it in the dark and did not see any arcing.

All to no avail, speaker still popping. Not all the time, but often (daily).

Anyone have any ideas? I've contacted ML support and they are out of ideas too. When the popping happens it continues to pop even with audio cables disconnected so the problem is not with the source or cables. Unplugging power seems to make it stop (there's still audio for a few minutes).

Help!!

 

[ttocs]

My first guess is bad capacitor.

 

[JonFo]

Wow, that's a tough one, as it sounds like you have replaced the significant components that could be the source of the issue.

But none of the passive crossover elements have been changed, right?

If so, then I'd agree with ttocs, most likely a capacitor in the high-pass x-over network. Prodigies are pretty old by now, and a failing cap is not surprising.

The only other thought here would be the connector between the xformer and the panel, and maybe it is a bit corroded, ill-fitting, etc.

 

[roberto]

Hola
Is the problem present with the speaker wire connected? To charge the panels first, play some music. Then turn off the amp and then disconnect the speaker wire. This looks to me a heavy electrostatic energy is building up from somewhere. That sound is a discharge. Check your ground of the house. The cd or dvd are electrostatic generators. And they polluted with this unwanted high frequency. Somewhere a static is building up and you have to find a way to channels it to ground.
I hope that you could find the failure. A faulty connection or a poor ground contact could be too

Happy listening!

 

[18000rpm]

Thanks for all the excellent suggestions. Some additional info:

When the speaker is popping and I disconnect the speaker wires, it continues to pop. Both speakers are plugged into a surge-protected power strip into the same wall outlet so I don't think grounding is the issue. But charge buildup sounds quite plausible. I have also tried plugging it into a different wall outlet directly and that didn't solve the problem.

Capacitors sound like a good place to look into. Here is a pic of the internals when the dealer was replacing the transformer (I vacuumed it lightly after taking the pic to remove the dust):



Link to full-res pic https://i.imgur.com/HhsBZtQ.jpg

Does anything stick out as a potential problem or likely needs replacing? Unfortunately I am not handy so I would need to take it somewhere to have anything replaced or worked on.

Thanks again for all the suggestions.

 

[Peter Hogan]

You can try swapping panels, to see if the popping follows the panel, or stays in the same speaker, that will let you know if it's the panel or speaker electrics.

 

[18000rpm]

You can try swapping panels, to see if the popping follows the panel, or stays in the same speaker, that will let you know if it's the panel or speaker electrics.

Yes I have done that and the popping stayed with the speaker, so it's not the panels.

Seems like the problem has been getting far less frequent now (the problem started after the speaker was unused for 3-4 months while I waited for new panels). Hopefully as I continue to use it extensively it becomes less of an issue.