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Friday, May 8, 2015

Beogram 4000: Adjustment of the Tonearm Height and Tracking Force

The big things are pretty much done in the Beogram 4000 that I am restoring right now (except polishing the hood...I am saving this for a day when I can't make it to the gym. Polishing is always a nice workout...;-). So I am now focusing on the details. I noticed that the tonearm rested considerably higher than the sensor arm when in lifted position. Here is a picture taken from the front of the two arms:

While this is nothing important with regard to sound quality etc..., it just does not look great. After I consulted the manual, which prescribes to adjust the arm to the same height as the sensor arm, I did the adjustment. It is pretty simple. There are two screws in the back of the arms that set the upper and lower limits of the tone arm movement. They are accessible after taking off the carriage cover (it can simply be pulled up and away from the arms). The two screws are indicates with red and blue circles:

The red one sets the lower limit. Obviously, this needs to be set that the tonearm lowers the stylus slightly below the platter ribs (the manual prescribes 0.5 mm below the high portions of the ribs - please, do this measurement with the belt removed...;-). The blue one sets the upper limit. This is the one I adjusted. The other one was set correctly. A few turns and I arrived at the right tonearm height:

Beautiful! On to the tracking force adjustment. It is crucial that the pickup tracks the groove at precisely the right weight it has been designed for. In the case of the SP15 cartridge that came with this Beogram 4000, the proper weight is 1g. A while back I made a video demonstrating this adjustment on a Beogram 4004. The setup is identical on the 4000:

The important thing about this adjustment is that one needs to adjust the zero weight first with the weight that is in the back of the tonearm. Once this is adjusted, the correct tracking weight can be determined using a tracking force gauge by adjusting the weight dial in the back of the arm. In previous Beograms it turned out that the tracking force scale on the arm is often less than accurate. The Beogram 4000 however seems to be precise in this aspect. My measurements showed that the adjusted weight is very close to the measured one on the gauge.

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