Siemens Relay Replacement with Sound Dampening Hood

After I changed all the capacitors on the main board of the Beogram 4002 (5521) i am restoring right now, the 45 RPM circuit stopped working while listening to a record with The Boss. I sought help in the schematics and decided to replace the two main relays (part 8009020) as suggested by Rudy from Beolover.

I couldn't find any drop-in replacements with the same specifications and dimensions and because of the customs when importing from US (Beolover) to Denmark I decided to make my own version of Rudys relay replacement part.

I decided to use almost the same relay as Rudy (i'm using the highly insulated Omron G6K-2F-Y) and with a little help from the schematics and a caliper i managed to create my own PCB schematics using Fritzing.

Finished model in Fritzing

Figure 1: Finished model in Fritzing

After receiving the PCBs and relays from China I soldered everything (first time working with SMD) and tested it in the Beogram 4002. It was working as expected and even quieter than the old Siemens relay.

Finished PCB

Figure 2: Finished PCB

Finished PCB with relay

Figure 3: Finished PCB with relay

I quickly found out that it was super difficult to solder all the small header pins vertically and parallel to each other so there was only one thing to do! I 3D printed a small base with room for the pins and a PCB which i glued to the top of the base. The soldering base makes it super easy and fast to solder these replacements. I just add the pins and fit another PCB on top of them and solder. Voilá!

Soldering Base

Figure 4: Soldering Base

I wasn't completely satisfied with the clicking sound coming from the relays when lowering the tonearm or switching between 33/45 RPM so i decided to create a 3D hood with sound dampening material inside.

Tinkercad Model of the Sound Dampening Hood

Figure 5: Tinkercad Model of the Sound Dampening Hood

The sound dampening hood was made in Tinkercad with almost the same dimensions as the old Siemens relay so it's easy to replace. I printed it in PLA as usual with a width of 0.2mm and a temperature of 204 °C.

After playing around with various sound dampening materials i decided to use Melamine Foam which dampened the sound the most. I added a drop of glue to the inner top of the hood and added the foam.

Sound Dampening Hood with Foam next to the relay

Figure 6: Sound Dampening Hood with Foam next to the relay

With a small indentation in the hood the PCB could easily be slipped into place. It was locked in place with a drop of glue and soldered back on the BG4002 for further testing.

All put together

Figure 7: All put together

Soldered back in the Beogram

Figure 8: Soldered back in the Beogram

It works perfectly and it's almost silent. You'll have to struggle to hear it. I'm quite sure that B&O would use a silent relay if it existed back in the 70'ies so this is as good as it gets!

If you're interested in the relay replacements you can contact me right here.