Monitor Audio RSW-12 - crackle and popping sound

[dobrykamil]

Hello

I've got above model and it works in general, but instantly after powering on, subwoofer produces very annoying crackle and popping sound. I believe this is another, common issue with this model. Most information on the internet is regarding hum, buzzing sound etc. caused by dodgy +15V, -15V rail caps.
I've managed to repair different MA subwoofer with exact symptoms in the past - BXW10. Problem is, amplifier for RSW12 comes with two IR2110 mosfet drivers working in full bridge circuit.Long story short, I've replaced both bootstrap caps (that was the case with BXW10) but it didn't help at all. I don't have SM yet, but I've emailed MA support team, so hopefully they'll come back to me soon. I believe problem is caused by one of the caps, because popping sound goes away (not entirely, becomes less frequent) once the unit warms up a bit.
Has anyone came across with this problem before?

Cheers

[petehall347]

Re: Monitor Audio RSW-12 - crackle and popping sound

popping is most times transistors

[momaka]

Re: Monitor Audio RSW-12 - crackle and popping sound

I believe problem is caused by one of the caps, because popping sound goes away (not entirely, becomes less frequent) once the unit warms up a bit.

That's a good clue there.

Heat usually affects two things the most: solder joints and electrolytic capacitors. When electrolytic capacitors are made warmer, their ESR spec improves. So it's possible you may have more bad caps in the unit, even if none look visibly bad (not uncommon for caps to go bad without showing it.) Likewise, solder joints inside the unit also get affected by heat, as things can expand and contract from the heat. Of course, it's also possible to have marginal (electrically leaky) transistors, as petehall347 suggested above.

With that being said, I advise you open the unit and inspect all solder joints first. Also take note of any caps that might be located in hot spots, especially small ones - those would be the first ones to fail. While at it (and waiting for MA to reply to you, which I don't think they will, TBH), you should post some pictures here.

[matyka]

Re: Monitor Audio RSW-12 - crackle and popping sound

Hello,

I would need some help with my BXW10 produces very annoying crackle and popping sound could you please let me what did you replace it. I don't see any bulging capacitor's.

Cheers