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Beogram 4004 plate suddenly slows down

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Danielle
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Danielle posted on Tue, Feb 25 2014 6:08 AM

Hello,

I have a Beogram 4004 that my father gave to me. I believe it is a 1978 or 1979 model.

The last day and a half I have had an issue where on 33, the sound suddenly drops as the plate begins moving much slower. I checked and the belt was on correctly when this happened. I assume there is a problem with the belt-turning motor. When I started it up later in the day, it worked fine for a while, until the same slowness suddenly started in again.

I am comfortable taking the plate/covers off the rig but I am not very proficient with some of the terms I've seen in other forums, and many people didn't have the 'sudden' change of speed like I was seeing. If someone could explain to me how I can diagnose this issue, I'd really appreciate it.

A bit of history here: The beogram wasn't used for about 10 years before this last year. It was working a year ago, but after studying abroad a year, I returned and now have this problem.

Thank you! 

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Dillen
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Dillen replied on Tue, Feb 25 2014 7:00 AM

Welcome to Beoworld !

These Beograms are famous for speed problems but most are quite easy to fix.
The speed setting trimmers on the main board can act up, so can the speed switching relay (where fitted) and
the fingerwheel-operated potentiometers on the operating panel.
Finally, the motor itself can be in need of cleaning and lubrication to its bearings.
All a bit technical, I'm afraid but, as said, fixable.

Martin

Danielle
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Danielle replied on Thu, Feb 27 2014 12:51 AM

I believe the potentiometer dials are operating correctly, as they still worked even when the plate was moving slowly. A B&O technician told me my potentiometers were in better shape than most Beo 4004s, since the back lights were originals and still working well.

It's safe to remove the motor by unscrewing it and removing it, right?  I'm planning on opening it up to see what's going on inside.

Where would I purchase new parts, if something is broken or worn out?
Where do I check the speed switching relay and the speed setting trimmers? 

Sorry to ask such simple questions. I'm trying to study this and learn it all for myself, which is difficult for a girl who grew up in the CD era. Sad

Andrew
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Andrew replied on Thu, Feb 27 2014 1:09 AM

Hi Danielle

The speed relay and trimmers are mounted on the PCB inside the Beogram underneath the platter (large circuit board). I would get them cleaned up before I begin looking at the motor as they are usually the source of the problem, not in all cases, but I'd prefer to check those before I begin to disassemble a DC motor which isn't easy to come by :)

The fact the globes are original doesn't have anything to do with the condition of the fine speed control dials on the top plate but the fact it continues to slow down even when these are worked suggests its likely the relay or the trimmers on the PCB inside the machine.

Hope this helps.

Andrew

Danielle
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Would you direct me to the speed relay and trimmers? Here is a screenshot of my board. Again, sorry for the lack of technical knowledge in this. I appreciate your help.

xSpxtPN

Rich
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Rich replied on Wed, Mar 26 2014 12:33 AM

I had issues with my 4002 not too different from you.  I will try to find that old thread for reference.

The trimmers are probably the round pieces to the right (in your photo) between the two orange and white wires.  They have a slot in them a small flat head screw driver will fit into.  If you put the small screw driver into the slot, you can "exercise" the trimmers by turning them all the way to the left, then all the way to the right.  "Exercise" them about 25 times and you may cure your problem.  Easy to do.  But then you have to reset your speed.  (I tried replacing these trimmers but that wasn't the ultimate answer in the end.)

The relay is the cube to the far right (in your photo) below the orange and white wire.  Sometimes cleaning the contacts of the relay solves speed issues.  Not as easy.


Danielle
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Danielle replied on Wed, Mar 26 2014 12:40 AM

Thank you so much, Rich!
Do you know how to reset the speed after exercising the trimmers?

Let me know if you find your old thread!  

Rich
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Rich replied on Wed, Mar 26 2014 12:43 AM

Rich:

I had issues with my 4002 not too different from you.  I will try to find that old thread for reference.

Check this old thread.  Lots of advice on speed issues.


Rich
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Rich replied on Wed, Mar 26 2014 12:45 AM

Danielle:

Thank you so much, Rich!
Do you know how to reset the speed after exercising the trimmers?

Let me know if you find your old thread!  

You're welcome.  I bought a strobe and speed disc, but you should be able to get very close by ear if you have an LP of something you know very well.  I imagine it can be done electrically if you have the service manual and the right test equipment.

Old thread link above.


Danielle
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Danielle replied on Wed, Mar 26 2014 12:52 AM

Oh, wonderful! Thank you! I will give this a shot tonight/tomorrow and see how it goes. 

Søren Mexico
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Download a speed disc, print on cardboard, cut to size, as you are in the US you will need a 60 Hz speed disc, then using a normal old light bulb you can adjust the speed.

What I would do is: change electrolytic capacitors and trimmers (potentiometers) and get a new belt, then adjust the speed, and if there are still problems, then and only then go for the motor.

Collecting Vintage B&O is not a hobby, its a lifestyle.

Danielle
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Where can I find electrolytic capacitors and potentiometers for the 4004? 

Søren Mexico
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Here or ask Martin (Dillen) on this forum, but if you dont know how to solder and a little bit of electronics, dont try it yourself.

Collecting Vintage B&O is not a hobby, its a lifestyle.

Danielle
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Great. Thanks again, everyone.

Søren Mexico
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Now dont give up, its a nice turntable and worth saving, keep us updated

Collecting Vintage B&O is not a hobby, its a lifestyle.

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