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?
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Beomaster 4000 - extra components not documented
2 replies
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
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