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Monday, December 7, 2015

Beogram 4000: Adjusting the Tracking Force and Replacing the Strange Original Front Center Cabinet Guiding Washer

The Beogram 4000 that I just finished up is now running smoothly. I am playing 'Song for My Father' by Horace Silver (unfortunately a reissue, since the original first pressings are unaffordable these days...sigh!!), which is one of my favorite jazz tunes while writing this post.
Before I got here, however, I still had to do a bit of work on this Beogram: Adjusting the tone arm weight and limits. I also replace the strange standard guiding washer that is typically found installed in the front center guiding slot to ensure a straight movement of the plinth when it is pushed back to secure the aluminum panels. Here is a picture of the original washer including the shoulder bolt:

This awkward setup just does not work well, and consequently later Beogram 400x have a much better design based on an eccentric washer shape. I recently designed 3D printed replicas of this design since they often crack in 4002 and 4004 models that are outfitted with plastic versions of it. See this video for their installation. The parts are available via my Shapeways store (five washers are needed to replace all of them).

Here is a picture of the new washer installed together with a new M3 bolt (note the much lower profile of the assembly, which is beneficial when installing the aluminum panels as chafing is avoided):

After this small detail, I did the arm adjustment. Most important are the zero weight and tracking force calibration and the proper adjustment of the arm lowering limit, which can be the final stop gap that keeps the platter from ripping the needle out of the MMC cartridge in case of a failing photosensor or misadjusted sensor bulb. Earlier I posted videos about these two procedures (tracking force calibration, arm lowering limit). Equally important is the improvement of the weight adjustment screw assembly, which I usually upgrade with a M3 nut and washer. This allows to permanently fix the adjustment in place, which is critical for a successful out-of-the-box setup when I send the turntable back to Italy. The original setup with the locking washer is too flimsy, which can result in a change of the calibration during shipment. Here is a picture of the installed nut:

And here the needle on the tracking force gauge at 1g after adjusting everything:

Ah...Horace Silver via a perfectly adjusted 4000 and my Beomaster 6000 4-Channel - perfect pairings!...I am in Beoheaven..;-)

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