Beogram 4002 Type 5513: Going over the chassis and mechanical parts

The two circuit boards that require recapping and other restoration work are done. Now it is time to dive into the Beogram 4002 cabinet and look in more detail at the electro-mechanical parts.

I like to remove the floating chassis to work on it. I plan on taking a lot of the tangential arm assembly apart anyway so removing the floating chassis makes that work easier for me.

As it turns out it also reveals some hidden problems.

I originally thought the three chassis lock down bushings were still good. They appeared to be intact but opening up the lock down mechanism proved otherwise.

First sign that the bushings were not in as good shape as I thought.

The more I handled the old bushings the more they fell apart.

Fortunately Beolover makes a set of replacement bushings so I quickly ordered a set from him.

Next up, a look at the condition of the tangential arm drive assembly.
I opened up the ball socket that houses the nylon nut the drive spindle rotates in to move the tangential arm assembly forward and back.

The old grease had started to harden up on this Beogram. The service manual says it should be an oily consistency. I will clean all of that off and reapply a new coat of lubricant.

Here are the tangential drive components removed and cleaned up.

When I reassemble the drive components I will also replace the original plastic pulley with a new, aluminum one I got from Beolover.

The above photo also shows that I had replaced the arm position sensor lamp with a new LED light source.

Here is the original LED.  They typically go out by now so I removed it and tested it. The LED was indeed dead.

I used an amber colored LED to replace it.

I will fine tune the lamp position as related to the angle its light hits the arm position sensor. There is a service manual adjustment for the expected sensor voltage when the lamp source is on.

I removed the original lamp source for the tangential tracking sensor as I will be replacing that light source with Beolover's LED replacement module.

With the light source module removed I can see that the metal tracking sensor shutter (that is attached to the tonearm base) looks like it is positioned correctly.

It mustn't rub on the black plastic housing of the tracking sensor but should be close to it. The service manual calls for a 1 mm gap.

The rest of the components that make up the tangential arm assembly are clean and move freely. I can see a few places where service manual adjustments will have to be performed but the arm lift and lowering  mechanisms move easily.

Other than a couple drops of synthetic oil on pivot points I don't see anything else that needs to be taken apart on the arm assembly.

I lubricated the tangential arm drive spindle with a new mixture of Rocol 1000 and Mobile NUTO H32 as called out in the service manual. There are other options if you don't have access to those products. I have collected some though so I like using what B&O originally used.

For the two shaft tie-rods that the tangential arm assembly rides on I applied a thin coat of white, DX Molykote paste.

The floating chassis is reassembled.  I just need to install the Beolover replacement bushings for the chassis locks then put everything back together in the Beogram cabinet base.