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This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022

 

Beogram 3000 not muted

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kimvdk
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kimvdk Posted: Mon, Jan 25 2021 6:14 PM

Hi,

 

I already have another thread on this Beogram 3000 (speed problem):

https://archivedforum2.beoworld.org/forums/t/45479.aspx

Still waiting for the oil..

But I have another problem with the turntable. It's like the turntable doesn't mute when not operating (should it?). If the turntable is turned off and I gently touch a sheet of paper on the stylus, I can clearly hear the noise in the speakers. I thought it should be muted when turned off.

Also when I play a record there's a "semi loud" popping noise comming from the spealers when the styles is going down/up on the record.

Maybe the two problems are linked together?

The turntable is connected to my amplifier through a RIAA preamplifier, but since the styles is also "active" when not turned on, that couldn't possisbly be the problem, could it?

 

Best regards,

Kim

kimvdk
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kimvdk replied on Sat, Feb 6 2021 2:07 PM

I've made a small video of the problem.

https://youtu.be/PfopJPqEv0I

You can hear the popping noise 3 times:

  1. Needle touches the record
  2. Needle raises from the record
  3. The motor turns off

Could it be a grounding issue between the turntable and preamplifier?

Or maybe these old capacitors that needs to be replaced inside the relay housing?

Thanks,

Kim

 

sonavor
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sonavor replied on Sat, Feb 6 2021 3:14 PM

If there was a grounding problem you would hear an annoying hum all the time.
The sound you are hearing is normal for an unmuted phono signal. I have a transcription turntable without any muting circuit and it does that same thing. 

I am not familiar with the workings of your particular Beogram but that does look like it could be a phono signal muting relay. 
Can you observe the relay assembly when the Beogram is turned on to see if there is any activity there?
It likely works off the lowering mechanism to unmute the signal so there may be a switch involved to operate the relay.
Does the service manual have an adjustment procedure for it?

-sonavor

Dillen
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Dillen replied on Sat, Feb 6 2021 3:32 PM

That's the start(stop relay.
The muting switch is a passive sliding switch sitting near the tonearm base, operated by the lift/lower arm.
The tonearm wires and the output signal cable all go to the muting switch (unless your Beogram has the socket for an internal RIAA, in which case
the socket sits in between).

Martin

kimvdk
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kimvdk replied on Sat, Feb 6 2021 5:21 PM

Ok, so it is not a grounding issue.

This is the back of the turntable and the tonearm base (I believe) with a red square:

Could it be that the switch should be cleaned with contact cleaner? (how can I get to the it without breaking anything)

Should I care about the capacitors (I find it strange though, that there appears to be an electrolyte capacitor when the whole unit is driven by ac..) I have red that many capacitors are failing on old electronic gear.

Appart from this the turntable is working very well (appart from that it doesn't always want to lift and return the tonearm when the record is finished, but thats a minor problem I think).

Kim

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