Vintage Synth Explorer Forums

The Roland JX10 and others have a vacuum fluorescent display powered by a small transformer oscillator. Today, because of the constant 15kHz vibration of the core, wires are breaking and the display goes dark. Roland is no longer stocking this part and Sumida will not produce a run of less than many thousands of units.
I have "autopsied" a coil and posted the results for anyone with a blind JX and the patience to re-wind the transformer


Pins are numbered clockwise when seen from the pin end (foil side of board)
Windings are all clockwise when seen from the TOP end of coil

Pin 1 and 2 27 turns #34 - this is the driver winding

Pin 3 and 4 17 turns #36 - these are the center-tapped filliment
Pin 4 and 5 17 turns #36

Pin 6 and 7 8 turns #36 - this is the feedback winding
Pin 7 and 8 148 turns #36 - this is the -38-volt winding
Pin 8 and 9 36 turns #36 - this is the -43-volt winding

Can this problem cause the screen to get extremely bright too?
My MKS-70 has this problem, all the segments get illuminated and it's just impossible to read anything...
I also noticed that the illumination also depends on the amount of segments that are supposed to be on, so if the text that was supposed to appear is really short, it is less bright than if it was a long text...


Thanks in advance

Paulo