Beogram 4004 From Canada: Mechanical Disassembly

 Today I disassembled the mechanical parts that make up the Beogram 4004 floating chassis and tangential arm assembly.  I do that so I can make sure everything is cleaned, checked and ready for lubrication.

The first step is to remove the floating chassis from the cabinet base.
That means disassembly of the lock down screw assemblies. Those are the three assemblies that have the rubber bushings that often need replacing.

Here is one of the three.  

To my surprise the original bushings on this Beogram are still in good shape.  I expected them to break and crumble when I pushed on them but they remain intact and still have some flexibility.

It is rare to find the original bushings still in this kind of shape so I will keep them.
I will, however, treat them with some Meguiar's Professional Vinyl & Rubber Cleaner & Conditioner.
I let the bushings soak overnight with the conditioner.

Here is the floating chassis removed from the Beogram cabinet.  Ready to take a deeper dive into the mechanical components.

Overall this Beogram is extremely clean.  The mechanical parts look like they are correctly in place too.
I did a quick check of the tonearm to fixed arm spacing and it is right at the desired 7.7mm distance.

I opened up the servo motor that drives the tangential arm assembly because it looks like the damping material around the motor housing is beginning to deteriorate.

I have seen this vibration damping material completely turn to dust.  This one still has structural integrity. However, I feel it is nearing the end of its useful life so I will replace it with some new damping material.

Next I removed the tangential arm assembly from the floating chassis to get to more areas I wanted to examine and clean.

From this point I can clean and lubricate the parts that are fixed to the floating chassis and I can work separately on the tangential arm assembly.

Here are some parts on the tangential arm assembly.

On the underside of the tangential arm assembly is a small signal transfer board. The phono audio signals (left and right) change from the very thin, enamel coated wires that go through the tonearm pivot assembly to larger, color coded (and shielded) cables that take the signal over to the Beogram PCB 8 Output Board.  You can also see the underside of the solenoid for arm lowering.

I removed the light source assembly from the tangential drive tracking sensor as I will be replacing it with the Beolover tracking sensor LED light source.  This also gives me a chance to clean and check the tracking sensor and the diaphragm that is mounted to the tonearm pivot. 

I also have the tonearm lowering damper removed. It was not moving very well even with the air valve adjustment screw completely removed.
After taking it apart I saw that it has some very thick grease installed. I will clean all of that off and lubricate it with some PMX-200 (Dow Corning 200 fluid).

I cleaned off the old oil and grease mixture from the tangential drive spindle components. The grease and oil mixture appeared as expected. A dark grey color.  But it likely has some dust mixed in with it from forty years of use so it is best to clean it and then apply a new lubricant.

The service manuals for the Beogram 400x turntables vary quite a bit on what is described for lubrication of the parts. The manual for the Beogram 4002 Type 5523 and 4004 Type 5526 don't even call out anything for the damper cylinder.  I found an earlier Beogram 4002 service manual however that calls for the Dow Corning 200 fluid and was able to find some.

Here is a photo I keep of my Beogram 400x lubrication products.  These are per the various Bang & Olufsen Beogram 400x service manuals.

Modern lubricant substitutes can be used of course. I just like trying to recreate the original ones :-).

My next post will get into the tonearm assembly. With the tangential arm assembly removed I can perform most of the restoration work on it including some of the mechanical adjustments.