I currently have a DD30 and a DC2 on my bench, both with a lot of excess noise in the audio signal. Meaning, during quiet parts of a tape (or simply pressing play without a tape), as well as during winding in either direction, I hear a lot of electrical/motor noise through the headphones. All the PCB screw are installed and everything is properly grounded as far as I can tell. I'm going to try replacing the muting transistors on both. Is this a viable fix? Is there anything else I can try to get rid of the noise? Thanks!
In case anyone is curious, it ended up being a grounding issue after all. Soldering a short wire from headphone ground to negative battery terminal solved my issue. I also had cracked traces on that very narrow section of the PCB next to the Play button, reinforced those with a couple cap legs. Now I just need a donor volume pot, as this one is very worn and is not quite balanced at low volume.
