A Roland TR-909 Analog Drum Machine in for repair. This one is from the producerteam of the group Fragma. I know these guys since years. They told me, that when switching on the 909, it comes to life, functions for half a second playing the crash cymbal and then went dead again. Then the TR-909 waits a few seconds to do that again, and that cycle goes for about 5-10 minutes. After that the Roland TR-909 behaves normal.
Measuring the 5V rail quickly showed, that the 5V was just over 4,3V, and slowly climbing.
It looked like a capacitor charging curve. So I changed the filter cap and voila: The Roland TR-909 was operating normal again. While I was hin here I decided to re-cap the whole PSU, since the next issue wasn´t far away.
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, GER.
Get in touch about your synth situation!