Often, this is caused by a loose grounding lug. Open the chassis and check the grounding wire; adding a lockwasher to the terminal lug often solves the issue.
Known for its "musical" 3-band EQ (High at 12kHz, Mid at 2.5kHz, Low at 80Hz). 2 Aux sends, 2 Stereo FX returns, and Stereo Tape I/O. Soundtracs Topaz 12 4 Manual
High-quality technical diagrams and schematics can often be found on the Internet Archive . Often, this is caused by a loose grounding lug
I fall into the latter category. Or at least, I did for six agonizing weeks. Mid at 2.5kHz
Yes—with conditions. The is not strictly required to operate the mixer. The channel layout is intuitive. However, if you plan to: