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Beolover SyncDrive: DC Platter Motor Replacement for Beogram 4002 and 4004 (Type 551x and 552x)

Late Beogram 4002 and the 4004 (Types 551x and 552x), which have DC platter motors instead of the earlier synchronous AC motors usually suff...

Saturday, May 12, 2018

Beogram 4004 (5526): Restoration of the Electronics

After rebuilding the arm lowering and tracking systems of the Beogram 4004 (5526) that I am restoring right now it was time to look into the PCBs and the reservoir capacitor. This shows the main PCB in its original condition:
This is a detail shot of the platter motor control circuit:
I replaced all electrolytic capacitors, the RPM relay and the RPM trimmers:
The replacement RPM relay assembly is available to other B&O enthusiasts. Just send me an email or use the contact form on the right. Once this was done, I moved on to the reservoir capacitor:

This Beogram was fitted with a single capacitance reservoir, which I replaced with a modern 4700uF capacitor outfitted with a 3D printed adapter that allowed bolting it into place using the original mounting strap:
The next step was the restoration of the output PCB. This shows the original board:
I replaced the electrolytic capacitors and the output relay:
And this concluded the restoration of the PCBs.




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