Help! This is a circuit from an actual Kurzweil SP2SX piano but it is faulty and failing to supply -5 volts to the pin 4 supply rail of two op amps (4580). I drew the circuit on EC to try and figure out why its failing under such a small load and frankly Im not surprised! There is also a lot of ringing on the output which I cant get rid of. Maybe there is someone out there more knowlegable than I who can mod the circuit to work better that it is. The top most supply rail was 12v with 5v going to the op amp but I changed it to 5v because it made no difference. The two larger caps on the right were originally 3300uF but changing the values brought the output up to nearer 5v negative and you can get more or less voltage by changing values of these caps. The output was fed to a 79L05 regulator, this probably cleaned up the output but then the circuit put out Negative 4.3v which seems too low. The other rail of the afore mentioned op amps is +5v, so I assume the negative rail which is this circuits output should be Negative 5v.
