Beomaster 4000 – extra components not documented

[Mogens Ranneries]

Hi Forum. I am recapping another Beomaster 4000, but this version has 2 extra trimmers in the output stage, and I cannot find any documentation stating how to adjust them. It seems that they may effect the center/symmetri voltage of the output stage. See attached picture, which I scanned from the in-lay schematics. Unfortunately is does not say anything about adjustments. The extra trimmers are position 585 and 586 (right channel).

Anyone who has seen this version and knows the adjustment procedure?

[Dillen]

Adjustment of potentiometer pos. 585 and 586

Connect oscilloscope to the speaker output

Amplifier is fed 1 kHz sine, until clipping starts

Capacitor 4.7uF is mounted across C-E of TR43

Resistor 190ohm 23Wa (part# 5107005) is mounted across C-E of TR46

Potentiometer 5Kohm pos 585 is adjusted until distortion on negative peak

Resistor is moved to C-E of TR47

Potentiometer 5Kohm pos 586 is adjusted until distortion on positive peak

Left channel is adjusted as above

Martin

[Author]

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