This EMU SP1200 vintage drum computer came in with the following error description: Device turned on, but did not load any sound or OS. The 5V voltage was clearly underestimated at 4.3V. The 5V voltage regulator measured around 100℃. Desoldering and testing under load the voltage still was still too low.
I replaced the faulty voltage regulator with a modern setp down regulator (drop in replacement).
That makes the EMU voltage much more stable and temerature is now around 25℃ instead of 100℃! I measured all electrolytic capacitors and replaced the tantals. Floppy disk drive still had no read / write function. On customer request exchanged against a modern HxC drive. I also detected Bouncing buttons. In consultation with the customer, all buttons were replaced with new ones and, in addition, all sliders were cleaned.
I’m documenting repairs for my reference and yours. I do synth restorations and repair with a specialty in vintage synthesizers, drum machines and other vintage gear, based in Düsseldorf, GERMANY
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