Roland SH-1 Synthesizer Repair Service. A regular customer brought me this analog sweetheart. Sample and hold did not work properly. The "sampled" sound was not kept stable and "echoed" strongly, especially at low playback speeds.
At first I suspected cold solder joints. But on closer analysis, the S&H circuit got too much noise, so that multiple triggers were triggered. However, so that the entire noise level on the trimmer did not have to be reduced, I modified the S&H circuit a little and weakened the input signal a bit.
As before, I cannot understand that technicians only replace the power supply electrolytic capacitors on these devices, but leave this plague of Matsushita destroyers in the device. That this "purple" plague destroys our beloved synthesizers is well known and is well documented on my website.
I then cleaned the keyboard contacts and the audio jacks. These were also badly corroded. Just click on the picture for an after / before effect.