[gamlemis]

Hi,

i am rebuilding a BM 8000, today i have tested the power amplifiers on the bench, the idle adjustment went well 18 mV across the test points, but the offset voltage i cannot adjust to correct value when adjusted to lowest voltage 0,3 V the 100 ohm trimmer is all the way to one side??

the lowest output DC is 0,3 V ??

i have tried to renew the transistors in input diff amp. with matched transistors but this did not change anything?

Both amplifiers has the sam DC output of aprox. 0,3 V??

Can anyone give me a clue of where to search for this error?

Kind regards

Claus

[gamlemis]

Hi again,

the answer to above is:

both the audio input terminals has to be grounded to P37 (when amplifiers is out of their original compartment) to make this adjustment! otherwise one side of the input differential amplifier is undefined 0 !

now DC offset 0,0 mV

Thanks to Beolover, have a nice day

[Author]

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