Korg i5s annoying sound!

[virtuoso]

Hello,I still use this keyboard for some small venues,but lately it produce a strange ticking sound which occurs about 15-20 minutes after turning on,allthough it can not be heard when you play a sound,only when you don't play for about 3 seconds.I changed the internal battery but the sound is still apearing.

I recorded this effect on a PC so please hear it and hope you can give me some advice:

https://www.box.com/files/0/f/0/1/f_2112513833

[mash]

Hi virtuoso,
I don't have a solution to the ticking noise after 15 or 20 mins.
My Korg i5s has started making annoying "tearing" noises though, as soon as I press any key or hit the demo button. The noise continues until I press the "Global" button or stop the demo song.
I found a Korg i5s service manual is on: http://floppy.shugart.free.fr/materiels ... manual.pdf
The noise is still there ( headphones) when I disconnect the AMP PCB and loudspeakers so I think it's a problem with the main PCB KLM-1865. I've replaced the D/A converter IC TDA1305T but that didn't fix it. Would anyone have any suggestions or know where to buy a KLM-1865 circuit board ?
Thanks,
Mash.

[virtuoso]

Hi mash,it would help if you could record that noise to see what kind is,I still think that the sound on my case could be from AMP part,maybe some old capacitor,otherwise finding an old OPAMP or similar part could be hard thing to do.