Beomaster 4500 IR Noise/Buzzing

[jacope]

Hi all,

I have a Beomaster 4500 (type 2963, SW 1.6) and Beolink 7000. Every time I press a button on the BL7000, I get a pretty loud and definitely noticeable buzzing noise through the speakers. Just a pulse, not a sustained noise. Happens on both Powerlink and Speakerlink. I noted that this issue does NOT occur when using a Beolink 1000 or BEO4 , which makes me think it has something to do with the IR Transmitter section. I replaced a blown 10uf cap (5C110) which I was hoping would solve the issue, but it remains. Couldn’t find anything else of note on PCB5, other electrolytics tested good. Fixed a few dry joints but they were not relevant to this circuit.

Has anyone seen/fixed this problem? Any ideas would be great, thanks!

My B&O Icons:

[jacope]

I have also confirmed with my phone cameras that the noise occurs every time the 4 IR transmitter LEDs flash. The noise does not change with the speaker volume – always the same, even at zero.

My B&O Icons:

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