The 'super quartet' is a mixture of TR-707 drum samples and JUNO-106 synth architecture forming a 4 voice juno and a 2 voice no-noise juno..with unfortunately no user RAM backup battery. Original patches can be loaded apparently but not saved on board! On the upside it is compatable with most JUNO-106 software I read and patches can be dumped via MIDI from JUNO-106. ALso it has velocity sensetivity where the Juno does not. Difference in Chorus someone mentioned. Not sure what.
Always verify power supply voltages if problem looks like it could remotely be power supply related. See JUNO-106 regarding module failures etc.
Roland may still have some parts for these. If there's something you can't find including bbd's
Contact Sound Doctorin'
12/06 GOOD NEWS!!!! I've purchased and tested one of the 40 euro module redesigns. GREAT WORK! This should drive the price of the used modules down since these are way more reliable and sound identical! Here is the Module Retro page. This device must be hard wired which takes a few minutes but well worth the effort to get something in using common 13700 ota's.