I'm having trouble biasing a Rogue ST-90...

Discussion in 'Audio Hardware' started by marmil, Jan 21, 2023.

  1. marmil

    marmil It's such a long story... Thread Starter

    If anyone knows anything about doing this, please contact me privately. Tks.
     
  2. Strat-Mangler

    Strat-Mangler Personal Survival Daily Record-Breaker

    Location:
    Toronto
    It would help if you could elaborate as to what it is about it you're experiencing issues.
     
  3. marmil

    marmil It's such a long story... Thread Starter

    The instructions (pg 6: http://www.rogueaudio.com/manuals/Stereo90_Manual.pdf) explain how to do it but no matter what I do I can't get the meter to move. My best guess at the moment, is that the meter got shook up somehow coming fro Detroit to CT...
     
    Strat-Mangler likes this.
  4. avanti1960

    avanti1960 Forum Resident

    Location:
    Chicago metro, USA
    trouble with all 4 tubes or 1?
    try working the rotary switch back and fourth about 100 times in case there might be corroded contacts.
    the potentiometers have a lot of travel- make sure you are going from end to end.
     
  5. marmil

    marmil It's such a long story... Thread Starter

    All 4.
     
  6. avanti1960

    avanti1960 Forum Resident

    Location:
    Chicago metro, USA
    i would e-mail or call rogue audio. they are extremely helpful
     
  7. marmil

    marmil It's such a long story... Thread Starter

    That's my plan for Monday AM.
     
    Strat-Mangler likes this.
  8. vinylontubes

    vinylontubes Forum Resident

    Location:
    Katy, TX
    Honestly, this should be straight forward. The only issue I could see is that all of the tube circuits to the meter are closed. You need to bias each tube individually. That means closing each circuit one by one. The default setting should be with all of the circuits one, then one by one close the circuit set the bias the reopen the circuit to move to the next tube. At the default setting, there should be no voltage on the meter.
     
  9. ghn5ue

    ghn5ue Forum Resident

    I am assuming there is also no sound through your speakers? If that is the case, it is a power supply issue. There is one fuse hidden under the metal cover over the circuit board that could cause your issue. A broken or dislodged wire could also be your issue. Was there any smoke or unusual sounds when you powered the amp up the first time? If not, it is probably something simple like the fuse or a wire breaking off the circuit board in shipping. These amplifiers have the transformers mounted on a suspended plate to keep vibration out of the chassis. Because of this, there is a wooden board that is supplied by Rogue that is bolted from the underside of the amp for shipping. If that is not installed, the transformers would be rattling around which could cause wires to break where they attach. This is covered in the instruction manual you can download from Rogue. They refer to the board as a shipping pallet, but it is just a flat piece of wood. Fixing a broken wire would not be a complicated repair, but with the high voltages of tube amps you should have some electronics experience before poking around under that metal cover over the circuit board.
     
  10. marmil

    marmil It's such a long story... Thread Starter

    I got it to work. It was user error.
     
    aorecords and Strat-Mangler like this.
  11. ether-bored

    ether-bored way out west

  12. marmil

    marmil It's such a long story... Thread Starter

    Ain't it the truth!!
     
    ether-bored likes this.
  13. aorecords

    aorecords Forum Resident

    What were you doing wrong?
     
  14. marmil

    marmil It's such a long story... Thread Starter

    That, I haven't quite figured out. I think it was an odd combo of things including reading a passage from the manual incorrectly over & over & over...
     
    aorecords likes this.

Share This Page

molar-endocrine