By popular request (really, I got quite a few emails about this!...;-), I finally completed my Beogram DC motor restoration video! It demon...
Monday, May 22, 2017
Beogram 4004 (5526): Restoration of Arm Lowering and Tracking Systems
After a first look 'under the hood' and a discussion with my customer about what should be done I set out to rebuild the arm lowering mechanism and the tracking system. This shows the arm lowering mechanism in place:
I took it apart and cleaned and lubricated the components:
After reassembly, I realized that the solenoid was not bolted in the correct position. This can be seen by the alignment of the solenoid lever that did not align in parallel with the threaded rod that drives the carriage when fully extended:
I shifted the solenoid until parallelism was achieved:
Then it was time to look after the linkage that connects the damper with the tonearm. This requires the removal of the sensor arm. This shows the arms from the back:
and after extraction of the sensor arm and removal of the linkage (be careful not to loose the small spring that is under the linkage - it easily jumps to an unknown location in the space-time continuum...;-):
After cleaning and lubricating I reinstalled the arm and adjusted the arm parallelism:
The next step was to replace the incandescent light source of the tracking sensor with a Beolover LED based replacement unit. The original set-up is shown here:
This shows the original and the replacement in comparison:
The LED is approximately in the same position like the filament of the bulb. This picture shows the replacement installed:
The final step is cleaning/re-lubricating the threaded rod that moves the carriage and the installation of a new pulley (provided by Nick - let me know if you would like to obtain such a pulley and I will be happy to get you in touch). This shows the original plastic pulley:
They are cracked in most Beograms, i.e. I usually replace them even if they are still in decent condition such as this one. Beolover restorations aim to achieve long-term reliability and so we usually exchange all parts that have an established failure history. This shows the new aluminum pulley installed:
Beolovely! On to restoring the PCBs and replacement of the reservoir capacitor.