Achieving a smooth tonearm transport (BG4000)

[etype76]

I’ve been enjoying a fair bit of music on the 4000 this week and most kinks have been dealt with (until the next one).

Now, my attention is on the smoothness of the tonearm mechanism as it travels back to the start position. Although it’s stable it vibrates a bit much for my liking. There are also 2 distinct clicks as it moves back, not sure if this normal kind of hard to identify where from. I wonder is it’s the red plastic indicator slider.

I basically used silicone grease on rails and threaded shaft. I’ve read about the proper grease mix B&O used but it’s unobtainable where I am although there are plenty of other greases on the market such as “super lube”.

Any recommendations on how you got a pleasant operation of this transport?

[Jonathan McCall]

I’ve used dry lubricant on my Beogram 4500 – Molykote D321R, although yet to see how it performs, as I’m chasing a couple of other gremlins.

[hcraig244]

The vibrations you mention could be caused by a number of things, I too have used silicone grease on the threaded shaft, however i removed it from the rails as it was collecting dust and although not causing any noticeable issues i felt that it wasn’t necessary, look to the drive pully and its alignment to the motor spindle pully, also check that the threaded shaft is not bent….i have seen this in the past. Regarding the clicking sounds on the return run this will be the slider contact switches getting operated as the arm returns, you wont normally hear this on the way in as the arm moves relatively slowly compared to the run out.

enjoy

[etype76]

Thanks all, I removed the silicone grease and applied a thin layer of a multi-purpose grease and the vibrations are lesser. I’d like to ask another question but I’ll put it here whether or not related. This concerns the pulley. Playback is fine but the pulley makes its first revolution once the stylus hits the record after about 10 seconds…then it revolves a couple of times as if to ‘catch up’. This can be visually observed looking at the tonearm and sensor arm. Is this normal? I don’t remember seeing it previously but I may be wrong. As I say, playback seems unaffected.

[Mark-sf]

The servo should not activate as the arm is lowering. It sounds like the tonearm needs tracking adjustment. Follow the procedure in the service manual.

[etype76]

Hi, I’m not quite sure what you mean. The servo motor spins as the arm assembly moves towards the record. The arm lowers but there’s a significant delay before the first revolution of the pulley. I checked a video I took a couple of months ago and the first revolution occurred pretty soon after the stylus drop. What specific adjustment relates to this in the SM?

[etype76]

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I thought I could embed a video but obviously not. I can’t delete it either.

• This reply was modified 2 days, 13 hours ago by etype76.

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[hcraig244]

Ok

Your tracking servo is working fine, the servo is only activated after the tone arm is lowered..check out the video Belover posted on U tube for a good explanation of the circuits involved

craig

 

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