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Afternoon,
My son plays the piano and we were fortunate to be given a Korg concert EC100H electric piano for free recently. It’s had a few issues with the speakers that I’m now trying to rectify.
When you turn it on the right speaker (blue and black wires) has a static noise for 10-15s, and then goes quiet. There is no sound coming from that speaker when you play. The other is mostly fine but has a lot of reverb on the low notes and I discovered today the speaker cone is damaged. Easy fix to replace the speaker but I can’t work out why the other one doesn’t work apart from initial static. I’ve swapped the speakers over and both work. I’ve traced the wiring back to the main circuit board and wires intact. All the visible components look fine, nothing bulging, blown or noticeably damaged.
Does anyone have any ideas of how to get it working again? Thanks very much Chris
Video: https://streamable.com/p1e2hs
The fact that both speakers work suggests it's something else. Does it work fine with headphones? Do any of the capacitors look like they're bulging/burnt out?
The fact that both speakers work suggests it's something else. Does it work fine with headphones? Do any of the capacitors look like they're bulging/burnt out?
It’s fairly old so only has aux output. All capacitors look fine. Strange one!
Evening, any inspiration gang? Thanks
It might be easier to get a small amp that will connect via aux out.
When you say you've traced the wiring back, do you mean to the white pcb or the green one?
Back to the white pcb
The video is no longer available.
I'd certainly try plugging headphones or something into the aux to help see whether the problems go back to the pre-amp or are limited to the power amp/speaker side.
You can get basic multimeters for 10 plus pounds that'll help you diagnose things like this. Ideally, you want a better one that can test capacitors, but even being able to test voltages and resistances helps. For example, you can check whether the speaker coil is intact or blown.
Electrolytic capacitors are a common failure component and they can dry out without being visibly damaged.
Yeh try an external amp/speakers via the aux out?
Thanks everyone. I’ve dug out some old speakers and waiting on a new cable tomorrow. Will report back. Cheers
Back to the white pcb
That's the power amp board, so there should be a low level left and right channel coming in from the other PCB. I reckon it's the pair of black and red cables on the right. I would check those connections and then swap if the keyway makes it possible. That would prove if problem is on the PA board or the digital board. If handy with a soldering iron, by default I'd reflow the digital pcb in case of a dry joint. I'd assume (but could be wrong) the static burst could be some kind of signal detect circuit - when that channel gets no signal it shuts off after a delay.
Thanks for the advice. A few false starts but external speakers seem to work (still have the static at the start). Thanks again