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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...

Friday, August 11, 2017

Beogram 4004 Type 5526: Electrical & Mechanical Work Complete...First Play Test

I will begin this post with a picture of the Beogram 4004's first play test. It feels great to listen to some Stevie Ray Vaughan playing while I compose the blog report.

To get to this point from the last post I had to install the two Beolover replacement LED modules for the speed trimmer indicator lamps and run the 24 hour platter speed stability test.

Here are some pictures of the speed indicator LED replacement.































The LED lamp replacements on this speed trimmer circuit reduce the load on the Beogram motor control enough to show up as a final improvement on the 24 hour speed stability test. This of course goes hand in hand with the Beolover restoration of the DC platter motor, new trimmers on the main board and the new RPM speed selection relay.



Here are two plots of the 24 hours speed tests I performed on this Beogram motor. The first one, back in May, was with the Beogram before any restoration. The second plot, from the last 24 hours, shows the dramatic difference in the platter speed test results after the completed mechanical and electrical restoration work.


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