Hi,

I search the service manual for the technics synthesizer SX-AX7. The power supply isn´t working well. Only LCD backlight is lightning. Output voltages are .15V, +15V and regulated voltage of 5V.
The measurement revealed -15V, +15V and 3,5V. The 3,5V are to low for the integrated circuits.
The 5V are generated with a mitsubishi circuit 5291 (DC DC converter) and a zener diode of 5V and a transistor 2SB953A and various resistors and capacitors. Today I will check this components.
It would be better with wiring diagram.

Wolfgang

 

To switch on the synthesizer the 5V reduced to 2,4V. Not enough to the circuits. Without service manual it is difficult to determine where the error occurs.

 

Hello,

You already have a thread for this:
Service manual Technics SA-SX7 Keyboard

One is enough.

Bertus