This blog post details the functional restoration of a Beogram 4002 (Type 5513) turntable from a client in Florida. A previous post documented the initial assessment of the unit.
Upon beginning the restoration, the turntable was in relatively original condition. However, the platter motor showed signs of prior work, evidenced by an incorrectly installed pulley.
To address this, the motor was removed and disassembled to extract and lubricate the bearings. This involved immersing them in motor oil under vacuum until air bubbles ceased to appear, indicating the bearings were properly saturated.
While the bearings were undergoing this process, other mechanical components were addressed. The carriage mechanics, including the arm lowering and lateral translation systems, were disassembled, meticulously cleaned using ultrasonic and chemical methods, and then reassembled. A key part of this process involved replacing a worn rubber washer on the damper plunger with a suitable replacement to ensure accurate and reliable arm lowering.
Another area of attention was the linkage connecting the damper to the arm. This required removing the sensor arm fixture, which revealed a common issue: a detached copper plate responsible for facilitating smooth arm movement in the up position. This plate was securely reattached using epoxy after cleaning off the old adhesive residue.
Next, the bulb-based tracking sensor light source was replaced with a more modern and reliable LED-based system. This upgrade included installing a potentiometer for adjusting light intensity during calibration. Additionally, a cracked carriage pulley, a common issue with these turntables, was replaced with a precision-machined aluminum replica.
Moving on to the electronics, two light bulbs in the RPM trimmer panel above the keypad were swapped with drop-in LED replacements. Further electronic restoration involved addressing the control system’s reservoir capacitor, which is prone to leakage and performance degradation. A new, higher-quality capacitor was installed.
The main PCB received similar attention. All electrolytic capacitors, the relay, power transistors, and the sensor transistor, which often suffers from reduced gain and unreliable record detection, were replaced. The sensor transistor’s biasing was calibrated for optimal performance.
A final electronic modification involved relocating a trimmer potentiometer to a more accessible location and verifying its functionality. The sensor response was tested and found to be well within acceptable parameters.
The output PCB was also refurbished. This included replacing the relay and its associated time constant capacitor and adding a switch to connect the signal and system grounds, a measure that can effectively mitigate ground hum.
With the electronics addressed, attention shifted back to the mechanical aspects. The transport lock bushings, often found deteriorated in DC motor Beograms, were replaced. The turntable’s enclosure was thoroughly cleaned to remove any debris from the old bushings.
The plinth guidance washers, although already upgraded to metal ones, were missing a crucial component. A missing washer was replaced, and a nylon replacement was used for another location to enhance performance.
Finally, the RCA plugs, which exhibited significant corrosion, were replaced with new, gold-plated connectors for improved signal transfer.
After a successful 24-hour RPM stability test, the turntable underwent a series of adjustments and calibrations. Platter height, level, and alignment were meticulously set, the sub-chassis was checked for free-floating movement, and the arm lowering limit was adjusted for optimal safety.
Further refinements involved replacing the counterweight’s fragile circlip with a more secure nut, ensuring accurate and stable tracking weight calibration. The tracking weight itself was then carefully calibrated using a digital scale.
After a thorough cleaning of the aluminum panels, the turntable was reassembled and treated to a test run with a meticulously cleaned vinyl record. Despite the successful functional restoration, some cosmetic imperfections on the plinth and keypad remain.
Further testing and observation are planned to identify and resolve any intermittent issues before returning the fully restored Beogram 4002 to its grateful owner.