Beomaster 7000 audible ticks when display changes value

[Kees De Groot]

Hello all, what a treasure this forum is!

I recently acquired a Beomaster 7000 in great condition with a pair of Beolab 9’s. It sounds great and works well in combination with the cassettedeck and CD player 7000. However, I noticed that when I change the volume a tick can be heard in the speakers (during low volume passages, or without any music playing). I think it has to do with the display lighting up, as it seems to be ever so slightly louder when an “8”is displayed versus e.g. a “1” (the more segments light up, the louder the tick). Is there any way to fix this, for example by replacing capacitors?

I have already changed the trafo from 220 V to 240 V and that reduced the heat output. I’m planning to replace the filtre-caps and the two relays. I’m wondering if I should take any other capacitors into account (perhaps in the front panel?)

Thanks in advance, hoping to get some input!

—Kees

[TK]

Possibly sounds like you are hearing the datalink signals that are sent via the powerlink cables to alter the display on a datalink-enabled speaker. How about when you change the source input – does that also create a “buzz-buzz” sound?

Just to geek out a bit – The electrical pulses (representing the inverse binary of the number) are picked up by the music signal in cheap wiring. Interesting that “8” is louder than “1” – probably has to do with the signal pattern.  In the actual signal, “8” would be a bitstream of “0111” and “1” would be represented as “1000”.   I’ve read that buying higher quality shielded cables helps with the problem, but it could also be a fun project to alter the datalink transmission protocol via a series of dongles so the datalink signal is sent via some other means, perhaps over WiFi.

• This reply was modified 2 hours, 47 minutes ago by TK.

[Kees De Groot]

Hi TK,

That sounds rather interesting indeed! I have decided to recap the BM using the kit provided by DK Sound Parts, I’ll see if that changes anything. The PL cables I have currently in use are made by B&O and are (I think) the MKII kind: they’re quite slender plugs (tiny Bang & Olufsen logo) with a thin cable. Should be the shielded kind. It should work, considering they are original cables! Changing source does not give the same ticks.

I can follow your reasoning as to why and how the pulses may be the cause. However, changing the bass/treble levels (and thus displaying different values on the display) gives the same ticks. Would you say the bass/treble information is also transferred to the Beolabs through Datalink the same as the volume level? In that case I had no idea the speakers were managing the EQ and not the pre-amp in the BM!

best, Kees

 

[Kees De Groot]

I just checked and when I switch SOURCE from AUX to TAPE (BC7000 switches on), the tick is also audible. Moving SOURCE to the BGCD7000 does not give a tick. I’m confused! I’m waiting for the service kit and will report back if that fixes it.

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