Akai 4000DB Reel to Reel Preamp

I unsoldered and re-soldered the trimmers for level ajustment of recording, playback and monitor. Now when I turn on the recorder there is a noise coming from the two channels, what could it be? What should I do?

I attached the video with the behavior of the machine.
 

Attachments

  • akai.mp4
    3.2 MB