BeoGram 400X · Open source part
The original sledge motors in the BeoGram 4000 series can get noisy and unstable, and their bearings can't be serviced. I replace them with a modern Portescap motor, with a Maxon motor as the alternative.
The sledge motor in the BeoGram 4000 series drives the carriage through the servo belt. The tracking servo steps it during play, and it runs at full speed when the carriage travels in and out. It doesn't wear as quickly as the platter motor, but now and then I find a noisy or unstable one, and they're hard to restore because the bearings are fused into the motor housing.
The original motors were the Maxon 2023.913-11.111-002 and the Escap 22 C11 210 1. I replace them with the Portescap 22DCP Athlonix, the modern motor Portescap (formerly Escap) recommends in place of their original.
It fits the original housing and is silent at low speed. At full speed it runs a little fast and has a low hum, which I damp with new foam in the housing. Its 2 mm shaft is slightly larger than the original's, so I designed a 3D printed pulley to fit it.
The Maxon DC-max 22 S also works as a replacement. Its speed constant is within 2 rpm/V of the original's 608 rpm/V.
Replacement sledge motor for the BeoGram 4000, 4002 and 4004: the Portescap 22DCP Athlonix, which replaces the original Escap 22 C11 210 1. It fits the original housing. The 2 mm shaft is slightly thicker than the original, so it needs a new pulley, or the original pulley drilled out to 2 mm. It runs silently at low speed and with a low hum at full speed.
More work
Relay replacement
The original relays in the BeoGram 4000 series wear out with age. I replace them with my own relay PCBs, built around modern Omron relays.
LED tracking sensor
The BeoGram 4002 tracks the groove with an optical sensor lit by an incandescent bulb that dims with age. I replace it with a calibrated LED on a small PCB.
LED RPM adjustment lights
The bulbs behind the 33 and 45 rpm scales on the BeoGram 4002 and 4004 panel have usually burnt out after more than 40 years. I replace them with a warm white LED PCB of my own design.
Speed testing with SpinDex
Every BeoGram 400X I restore is speed tested with SpinDex, an open source RPM logger I designed for the BeoGram 4000 series.
RIAA preamp
A new RIAA preamp for the BeoGram 4002, built around the OPA2134 in the same form factor as the original board. The second SMD prototype is built and tested.
Pickup mount
The plastic tab in the BeoGram 4000 pickup mount can break with wear and age. I replace the mount with my own nylon part and flexible PCB.
Restoring the keypad and chassis on a BeoGram 4002
Decades of use wear through the varnish and black paint on the BeoGram 4002 keypad. I strip it, have it professionally painted and refit it to the chassis.
Tell me about your BeoGram 400X and I'll get back to you.