JBL Eon 615 smokes

[Bigdrums]

Hi all: Back once again for the unequaled advice given by everyone here, THANK YOU

I have a JBL Eon 615 PA speaker that smokes just about every time I use it. I've only used it twice. I have taken the amp module off the back and can see the parts that are heating up and smoking. C21 & C34. The plastic outer covering is melting and expanding quite a bit. I believe these are .47uf film type caps. Fairly small, about 1/4" by 1/8" by 3/8" rectangular They can be found on the attached schematic on pg 12, lower right hand corner near the "tympany" logo.

The speaker still is working normally except for the smoke and sound pretty good. Can any one tell me what these caps are supposed to do in this circuit and what might be the likely cause of them going up in smoke?

BTW I have another just like it that works fine (no smoke) and a few extra amp modules that I believe produce no sound even after booting up normally. Harman, JBL's parent company seems completely unwilling to warranty this in spite of just last year having it replaced (they call it repaired) but they don't repair anything, just replace parts. And since all the parts were replaced with new ones, I say it is a replacement, not a repair. Shame on them!

jbl_eon615 (2).pdf

[x-pro]

We can see the matching frequency of 600 kHz on pin 4 of U2B.
Then we observe the 300kHz frequency on the left (according to the diagram) pins L1 and L2 relative to Common. For now without signal, without load.
These capacitors should be polypropylene capacitors, at 63V.
Check R19, R28, C23, C28, C31, C32, С19, С41, R21, R27. You will have to unsolder the capacitors for checking.

[The Dude]

Those caps look like part of a low pass filter. I can't imagine why they'd smoke, unless underrated or leaky. I'd just try replacing them.

[stereomonostereo2]

I'm glad you posted this as I ran into the same issue. A customer brought in a JBL EON 615 that was making weird noises that i determined were in the PCB with the processors. I ordered a new panel, installed it, bench tested and sent it on its way. That night, the panel smoked the same caps that you listed. I contacted the distributor and they sent a replacement panel. I installed it, bench tested and sent it on its way. Same result. Towards the end of the band's third set the caps smoked. This time I removed the small PCB from the burnt unit and installed it in the original panel. Since then it's been running fine with no issues. I still don't know why the two new panels blew those capacitors, unless its a flaw from the factory?