EV ELX112P Loud popping sound after power on

[magicaltrevor70]

Hi,

Really hoping someone can help me with this. I have two EV ELX112P Powered speakers, one of which has started to pop some time (30s - 1min) after powering up.

There are two inputs each with a level control, and after a bit of experimentation, I found that if I keep the level 2 control down to minimum, I don't get the popping sound. I'm guessing that there's some problem with a capacitor in this input circuit, but just wondered if anyone had heard of something like this before I get it repaired.

[magicaltrevor70]

OK, it's not specific to an input stage, repeat tests have shown that I was wrong about that.

So does anybody know what might be causing this? I can probably do simple tests, I'm comfortable taking things apart and I have a multimeter, I just don't have any electronics knowledge.

I should add that this happens with nothing connected to either input, I have tried it in my rehearsal space and at home so it's not related to the building power, and I have a second identical speaker that is fine.

[g1]

The amps in these are usually replaced as complete units. There is no service information available. They use SMPS and class D amps, which are things repaired only by experienced technicians.
You could probably try swapping different boards between your good and bad units, but even if you identified which board is defective, you would not be able to buy a replacement board, just the entire electronic module.
Here is an example of the replacement unit:

EV Electro Voice ELX112P Amplifier F.01U.174.478 - Speaker Exchange

[magicaltrevor70]

Ouch...annoying. Thanks!

The speaker works OK after the popping, so I can keep the volume down on power on (which stops the popping), wait until it's 'warmed up' then turn up the dial. Dunno how long it will last, but it's been OK like this for months

[AudioSystemsEngineering]

Just in case anyone else lands here: open up the amp module and power it on. make sure there is nothing metallic that can drop onto the amp !
Using something insultated - like a sharpie marker pen - carefully tap each of the T0-220 devices - there are some TIP31/32 transistors and a few other bits.
I found that one of these had picked up mid-range vibrations and the legs had broken off due to metal fatigue - i've seen this in several powered speakers by different manufacturers.
once you've replaced the device, use some silicone to stop it vibrating in the future.

[magicaltrevor70]

FYI I had these fixed by an electronics guy. The fix on the receipt says:

Found 2 transistors breaking leads, replaced, glued, test OK
Transistor 2SA1837 PNP 230V 1A TO220
Transistor 2SC4793 NPN 230V 1A TO220

[lennykhmel]

Trevor, I have the same issue, and the popping stops after it warms up which takes up to a minute. Did it get worse for you that you had to repair it? How much was the repair?
Thanks