Beomaster 7000 Humming Sound

[Sakul7]

Hi everyone,

I recently got my hands on a beautiful Beosystem 7000 and two Beolab 8000 speakers. Basically all parts have/had some issues, was glad to see that there’s such an active community 🙂
The speakers were initially not working, but I could resolve that with the usual foam replacement and minor fixes in the power supply.

Now I’m trying to fix the rest of the system and am a bit lost on the Beomaster 7000. I found several forum entries, but none were close enough to my issue to help me.
Functionally, everything seems to work fine. However, there is a rather loud static humming sound.

Issue: With both speakers plugged in via Powerlink there’s a very noticeable humming sound.

I tried to narrow down the issue, here’s what I go so far:

1. I tested the speakers with the line input and with a Powerlink to 3.5mm cable directly connected to my phone. Both work fine, no humming or other issues.
2. I tested different input sources on the Beomaster (CD via Beogram CD 7000, Phone via 3.5mm to Powerlink plugged into CD input, same plugged in to Tape input), all result in the same humming issue.
3. Tested the headphone jack at the front, cannot hear any humming here.
4. Switched around between output 1/2 and L/R setting on speakers. Does not have any influence, the humming is always there.

Two interesting things I noticed:

1. The humming increases significantly when the second speaker is plugged in. I.e. with one speaker it’s relatively quite, with both plugged in it, each is humming louder than the single one before. As noted above, which output is used does not make a difference.
2. When using the remote, I can hear the button presses in the humming (sort of similar to a phone receiving something next to a speaker).

I’d be very grateful for any tips on how to proceed or narrow down the issue. I have experience with electronics in general, but none with fixing amps, so I’m unsure where to start the troubleshooting.

Any help would be much appreciated!

Best regards,
Sakul7

[Mark-sf]

You haven’t mentioned which country version you have, but since both components have two-pin AC plugs, I would start by testing them in the same wall outlet without a power strip and flipping one plug if possible to see it the hum lessons. When you do this ensure that no other connection goes to either component including antenna cable. It is quite possible that it is a crossed ground or phase issue when the units are plugged into different outlets. Also a cable antenna or TV connection that has a CATV connection can introduce hum. This test will let you narrow it down.

[Sakul7]

Thanks for the response!

Everything was bought in Germany, so 230V with 2 pin plugs.

I tested with different sockets and flipped the cables around, but to my ears nothing changed, always remained the same volume and tune. Also when I plugged the CD source back in.

Are there any components that are prone to fail in these units? I read in several places that capacitors might go bad with age, could this cause something like my problem?

[Author]

Posts