I have a Roland AC-100u, an amp that seems to be broadly similar in design to the JC77 and other Roland amps. Not sure what years these were made, but it's not surface mount circuit board.
It has a chorus and reverb effects circuit, and the amp is producing a weird high frequency squeal noise right about at 3500hz with effects off, and 2900hz with them on.
It's coming from the effects (reverb / chorus) PCB. I guess this is "clock noise." When I pull the power to that PCB the noise goes away. Is there anything that can be done about it? The PCB itself is unobtainium and it's the one section that is surface mount.
Any help getting to the bottom of it appreciated. Schematic attached.
It has a chorus and reverb effects circuit, and the amp is producing a weird high frequency squeal noise right about at 3500hz with effects off, and 2900hz with them on.
It's coming from the effects (reverb / chorus) PCB. I guess this is "clock noise." When I pull the power to that PCB the noise goes away. Is there anything that can be done about it? The PCB itself is unobtainium and it's the one section that is surface mount.
Any help getting to the bottom of it appreciated. Schematic attached.
Last edited: