has anybody modified their Juno 106/HS60? AI told me an FM Filter mod is possible, as well as adding an external LFO with more shapes, but then could not provide me with references. Im an avid circuit bender, and can read schematics for the most part, would love any feedback or guides if anyone has done this or similar.

 

There are some interesting modification options for the Roland Juno-106 or HS-60 that are well-known in the synthesizer community. Here are some approaches that might be relevant to you as a circuit bender:

1. FM Filter Modification
FM (frequency modulation) modification of the filter is technically possible, but requires deeper modifications to the circuitry. The Juno-106 only has one LFO with a fixed sine waveform, but by adding an external LFO or modifying the internal circuitry, the filter could be modulated in new ways. Unfortunately, there are no specific instructions in the provided sources, but similar projects have often been solved by adding CV (control voltage) inputs to integrate external modulators.

2. External LFO with Additional Waveforms
The Juno-106's internal LFO only offers a sine waveform. To use additional waveforms such as square or sawtooth, you can build an external LFO circuit and connect it to the synthesizer's modulation path. One option would be to feed signals via the Bender input or other free pins on the board.

3. Chorus-In Modification
A well-known modification is the addition of a "Chorus-In" input, as described on a modified HS-60. This allows external audio sources to be fed through the characteristic Juno chorus, creating new timbres.

4. MIDI Control and Extensions
For better control via MIDI, there are projects like the Kiwi-106 upgrade, which offers additional modulation options and expanded MIDI functionality. This might be interesting if you want more modern control.

5. Filter Automation
There are reports of users attempting to directly control or automate the filter CV signals. This could be achieved through external CV control or MIDI-to-CV converters.

Circuit Bending Tips

Study circuit diagrams: The Juno-106 is well-documented; you can find circuit diagrams online (e.g., on deep!sonic).
Use test points: Many synthesizer boards have test points that can be used for modifications.
Safety Precautions: Since the Juno-106 combines analog and digital components, you should be careful when experimenting to avoid damaging any ICs.

If you have specific questions or need support with a particular modification, the synthesizer community on platforms like Gearspace or Reddit is often helpful.

https://www.matrixsynth.com/2011/04/roland-hs-60-modifications.html

https://www.reddit.com/r/synthesizers/comments/1e2pkoz/juno_106_filter_automation/
https://www.deepsonic.ch/deep/docs_manuals/roland_juno-106_anleitung.pdf
https://www.sequencer.de/synthesizer/threads/roland-juno-106-und-control-change.89709/
https://gearspace.com/board/electro...8167-roland-juno-106-filter-voice-tuning.html