Recent content by xratedpez

  1. xratedpez

    Noisy Amp Circuit

    For those who might be interested, I did an additional test last night. I swapped out preamps, from a Sony TA-2000f to McIntosh C28. The interesting new finding is that the noise persisted until the McIntosh powered on-- then the noise vanished. The self-powered amps now seem to be working as...
  2. xratedpez

    Noisy Amp Circuit

    Hi Folks, Trying to diagnose a noisy (buzz) in a pair of self-powered speakers - LV1020 by Braun. The buzz/noise comes from the midrange and tweeter only. I've replaced a variety of transistors due to other audial artifacts ("popping") which ultimately was traced to the BC157 transistors...
  3. xratedpez

    Braun LV1020 tri-amped active monitors restoration and noise issues

    Know this is an old post Josh but hoping I can help. The popping/crackling is likely a BC157A (or B) in the amplifier section of the affected channel. I have two of these amps that have exhibited this exact symptom.
  4. xratedpez

    Transistor Substitution Help...

    Does anyone know if any of these transistors I listed above are known to go noisy? I have 3 out of 4 of these units that exhibit the same exact behavior.
  5. xratedpez

    Transistor Substitution Help...

    You are a scholar and a great human being-- thank you!
  6. xratedpez

    Transistor Substitution Help...

    Hi Folks, while transistor substitutions had sometimes been difficult in the past, I'd taken a couple years off from doing restoration work and it seems even fewer through-hole components are available from reputable dealers (Mouser, DigiKey) now. I feel like I've looked up dozens but all are...
  7. xratedpez

    Transistor Sub

    I've uploaded the entire schematic here: https://imgur.com/E9T3tcy The issue is in mid-range circuit. I've replaced all transistors in the pre-amp stage. (I think) I've isolated the noisy transistor to the diode/transistor mentioned above. Lots of older silicon in this unit.
  8. xratedpez

    Transistor Sub

    I would want an hfe in the 'C' band, correct? Does the transition frequency matter for this application? Thanks!
  9. xratedpez

    Transistor Sub

    Here's the schematic, if it helps. Don't necessarily need a metal can transistor (I can adapt the case style). T632 in schematic:
  10. xratedpez

    Transistor Sub

    Anyone have a suggestion for readily available sub for BC341? I've found several but all are either 20 bucks a piece or NLA. Thanks!
  11. xratedpez

    BAX13 Diode Replacement

    Yes! Midrange circuit of tri-amped speaker. I have lots of noise as soon as I turn it on (generally). I've replaced the transistors in the pre-amp section and using a signal tracer (i believe) I've isolated the issue to the D631/T632 section of the circuit.
  12. xratedpez

    BAX13 Diode Replacement

    Anyone know a reliable equivalent to the old BAX13 diode? I've searched this forum and others and haven't turned up anything (which is a new experience for me!) Thanks in advance.
  13. xratedpez

    Transistor Replacement

    I'm not seeing a noise figure listed for the BC171B anywhere. It's an old device, maybe before they listed noise specifications?
  14. xratedpez

    Tube Preamp Transformer Meltdown

    Any tips on where to go for a replacement transformer?
  15. xratedpez

    Tube Preamp Transformer Meltdown

    No, in this unit I kept them as close to original as I could find.
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