Korg DW-8000
Another so-called “brick” on my workbench —something I’m not particularly fond of. The instrument showed absolutely no signs of life when powered up. A deeper investigation revealed that the power supply was at fault, specifically the loss of one of the +5V rails feeding the digital circuitry.
Interestingly, this power supply provides three independent +5V rails and one -5V rail, mainly because of the large number of digital ICs used in the instrument and their considerable current requirements. On top of that, the original design left very little power margin in both the transformer and the affected supply rail.
I replaced the faulty 7805 regulator, all electrolytic capacitors, and the rectifier diodes. To improve long-term reliability, I also replaced the remaining 7805 regulators with modern, higher-current versions and applied fresh thermal compound.
Once the synth powered up, it became obvious that a large number of keys weren’t working. The DW-8000 uses a keyboard similar to the Yamaha DX7, featuring metal contacts rather than the more common rubber contacts, although without velocity sensitivity (one contact per key). Those contacts had oxidized over time, causing many of them to fail. I used professional Kontakt Chemie products to remove the oxidation, protect the contacts from future corrosion, and properly service them.
After these procedures, the instrument was fully restored to working order. As a final touch, I replaced the RAM backup battery and fitted a dedicated battery holder for easier future maintenance.
