Synthesizer Reparatur
5. November 2018
Repair Firstman SQ-01 Vintage Analog Synthesizer
17. November 2018

If you want to have the latest OS installed into your Roland TR-909, which is Eprom V4, you have to consider that the 909 will no longer react to a factory reset. It also renders the tape save/load function dead.

Why people want to have Version 4 installed?

Roland TR-909 V4 Service Information