Beogram 4002 (5513): Rebuilding the Arm Lowering and Tracking Mechanisms, and Installation of a New Carriage Pulley

After rebuilding the PCBs of the Beogram 4002 (5513) that I am restoring right now, it was time to rebuild the arm lowering and tracking mechanisms. Usually these decks have some issues in this department due to hardened lubricants. This unit did not have problems in the lowering damper section, but the damper-to-arm linkage was severely stuck and only moving since the pin on which it moves had come loose. As usual I took the arm lowering section with the damper apart first, following the 'action sequence' in this department. This video shows how to rebuild the tone arm mechanism in detail. Here are a few impressions of this particular unit. The arm lowering mechanism:

After taking it apart for cleaning and lubrication:

After I put it back together, I removed the sensor arm to get at the damper to arm linkage:

This video shows how to get to the damper to arm linkage and re-lubricate it.

When I tried to remove the linkage for lubrication, it came off together with its pin onto which it was seized:

I needed to take it to my workbench to press the pin out. This is a slightly tricky procedure which greatly benefits from a piece of wood with a hole in it:

I put some motor oil on the exposed part of the pin and then pressed it though using a vise and a second piece of wood to protect the pin surface:

I did this a few times forth and back until I was able to remove the pin by hand:

then I reinserted the pin, which makes a decent press-fit with the sensor arm assembly:

Then I put the linkage back on including the small spring that presses it towards the sensor arm assembly:

Then it was time to bolt the sensor arm back in and do the arm parallelism adjustment. Both sensor and tone arm need to be parallel in lateral and vertical directions, and they must be orthogonal to the carriage rails.

the first step is to align the sensor arm base orthogonally to the carriage rods, and then align the sensor arm parallel to the base.

After that the tonearm needs to be aligned parallel to the sensor arm by shifting the small plate behind the tonearm counterweight:

Once this is done the vertical parallelism needs to be adjusted. This arm definitely needed it:

This can be done with the lower set screw in the back of the arm assembly:

Once this is done the arms are parallel in both directions:

This concluded the basic arm adjustments (tracking weight and arm lowering limits will be done once the  platter and sub-chassis are adjusted). The next step was to replace the tracking system light source with a LED based replacement unit to ensure long-term stability. The original incandescent bulb based assemblies are no longer available, and so an LED replacement is a great idea. This shows the original setup:

and after replacing it with my replacement part:

This shows the old and new parts in comparison:

The LED is in the same spot as the filament of the light bulb, ensuring drop in functionality of the replacement part. There is a video that shows the tracking sensor installation and adjustment procedure in detail.

The final part of the tracking system rebuild was to replace the old plastic carriage pulley with a turned aluminum pulley provided by Nick of Beoworld. This shows the original pulley:

The original pulleys have a tendency to crack and go wobbly, so this is a great upgrade to ensure trouble-free operation down the road. I'll be happy to get you in touch with Nick if you would like to install such a nice pulley in your Beogram 4002! (he also has them for the Beogram 4000 and the older AC 4002 types). This show the aluminum pulley installed:

Absolutely beautiful! This is Beolove!