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RCF325As make me crazy

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  • RCF325As make me crazy

    Hello there.

    I have had two RCF325A, with the problem known as "replace all MMBTA42/92 transistors" and it works. Thank community for the info.
    Unfortunately, one of them has +HV voltage on bass output rail. It seems that TL393 IC in error sense circuit is not working (I am waiting for the replacement, Mailman hurry up!!) because Error led is off, despite the irregularity.
    Nevermind, I know that irregular conditions are present and, for now, I am ignoring that problem. The main problem is the presence +HV voltage on output rail despite the fact that every component in power supply is OK, including both FET IRF/IRFP.
    Can you make me a suggestion, if you have any, based on your experience?

    Thank you, in advance!
    Slavisa, Bosnia

    Ofc...here is the sch. https://goo.gl/images/sZnL3G
    Additionaly, removing both fuses and measuring I have found +HV on the Q16's collector. Upper driving transistors are all ok.
    Can someone describe functioning of the power circuit about power FETs, I am not quite sure how it works..?? Does it switch between hi and lo voltage on output transistors
    Last edited by Misley; 10-25-2016, 07:26 PM. Reason: Adding the sch

  • #2
    It would be helpful, well essential really, to post the schematic. Without it there's nothing to comment on.
    Experience is something you get, just after you really needed it.

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    • #3
      Q13 desoldered collector. Now it is OK.

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