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biasing voltage of hitachi hma-9500

adeel

adeel

Active Member
hi friends i just restored and upgraded hitachi mosfet power amp hma-9500 .i need help to adust biasing voltage of on gate of fetes i see minimum voltage i can adjust is 290mv . As no service manual is avialable for hma-9500 . only service manual for hma-9500 mark 2 is avialable which having different circuit . i set the dc offset near 0mv and biasing to 290mv . Any friend can tell me what will be biasing voltage for mosfetes . thansks.
 
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Perhaps not a specific answer witout service manual . Its first time setting biasing of a mosfet amp so don't understand what are basic rules to follow when setting biasing of mosfet .
In mark two of hma-9500 there are test points in board so one can easily follow and can set biasing but in mark one no testing points .
 

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