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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...

Showing posts with label stylus. Show all posts
Showing posts with label stylus. Show all posts

Monday, August 24, 2020

Update of MMC Cartridge Box for MMC 1-5 Cartridges

A while ago I designed a storage and shipping container for MMC cartridges. Initially this container was only outfitted with an insert for the old style MMC20 cartridges.

I just designed a new insert specially designed to hold and protect the newer MMC1-5 cartridges:
It opens like a book. Just stick the cartridge in the specially molded holder:
The inserts are printed from flex filament, i.e. are a bit elastic for a gentle and safe fit of the cartridges.
That is how they look closed. A little window shows what is inside:
Beolovely! Like all our parts these boxes are available to other enthusiasts!



Wednesday, November 18, 2015

Beogram 4002/4004: Adjusting the Tonearm Lowering Limit

While the Beogram 4002 that I currently restored has safely returned to its owner I still owed a report on the final tonearm adjustments. Beolover blogs all tasks that are performed during a restoration! So here it is as promised:

An important adjustment on the tonearm assembly is the arm lowering limit. This limit prevents the needle from hitting the platter ribs in case the photosensor in the sensor arm fails. The electronic control circuitry has no way to detect this issue and prevent the arm from lowering. If the sensor fails the system will interpret it as 'record present' and lower the arm. This is the main reason why B&O came up with the lower platter rib areas, which are located at the touch down points for LPs and singles. This allows giving the arm a lowering limit that can be below the surface of the record, while still prevent the stylus from being shaved off by a rib should it ever touch down without a record present.

I made a short video about this important adjustment:


After I did this adjustment, I also adjusted the zero weight of the arm (see here for a video how to do this) and installed a nut and a washer to replace the original retaining washer that keeps the counterweight adjustment screw in the assembly. Unfortunately this washer results in a lot of play in the mechanism, which can result in a change of the zero force adjustment during shipping and set-up, i.e. is not acceptable for a Beolover restoration! Here are a couple of pictures showing the original setup,

and the modified one:
All good now in the back of the tonearm assembly!