HARMAN KARDON HKTS220SUB/230 humming noise

[Charlie86]

I have a problem with in HARMAN KARDON HKTS220SUB / 230.  It started humming even if it is not connected to any source.  The sound is very similar to that in the video.

 https://youtu.be/CkMOZc1W9Jw

I found a service manual but unfortunately I can't help myself with it.

 https://elektrotanya.com/harman_kardon_hkts_220.pdf/download.html#dl

I also tried replacing three capacitors and a resistor from link below, but Subwoffer is still humming.

https://www.ebay.com/itm/Reparatur-Set-V2-0-fuer-das-Netzteil-HKTS210SUB-230-Harman-Kardon-13-Teile-/363266392654

Any idea, how to repair it?

[cdev]

Is it the power transformer? If so, maybe you can replenish the varnish and dry it out in an oven. Search on transformer hum. Sometimes a vacuum is also used to suck out the air so the the varnish penetrates deeper.

[Charlie86]

Hi,

It uses switching power supply. Humming is comeing directly from speaker. Speaker vibrates.

[cdev]

You should check the capacitors for bulging or leaking, and/or high ESR. Loss of the filter function from caps drying out will make such a hum. Nine times out of ten, this is whats wrong, unless the receiver is fairly new.