Korg SDD-1000
Today, an unusual guest arrived at my workshop: a Korg SDD-1000 digital delay unit. According to its owner, the device had stopped powering on.
The first thing that came to mind was, of course, the built-in power supply. After a brief inspection, it turned out that the fault was indeed located there. The rectifier diodes forming the bridge rectifier had failed. Their purpose is to rectify the voltage supplying the 5 V voltage regulator, which in turn powers the entire digital section of the unit. As a result, the 5 V supply was missing, making the effect appear completely dead.
Besides replacing the diodes, which was my first priority, I also replaced all the electrolytic capacitors in the power supply module. The unit is quite old, and the capacitors were certainly no longer within specification, as confirmed by my measurements.
I also repaired the power cable mounting, as the cable had been cut and joined using a standard electrical terminal block. Needless to say, this was not a particularly safe solution.
With these relatively simple and quick repairs, the unit was brought back to full working order.
