electical problems with a Yamaha MT8-X

[Stef7]

Hi all,

i have voltage problems with my MT8-X. The entire Tape section doesn´t work anymore. It is hard to find the problem since i don´t have any schematics and don´t know the output voltages of the PSU. I´ve changed already the 7812, 7805 and the M5230L (i don´t know what the 1274 should be, my local dealer says it should be a Transistor?!??!).

All i know is that the output voltage of the 7812 connected on CN048 seems to be too few, because the LED´s start to light when i make a bridge on FR001. The 5230 provides also some volts, but the Mitsubishi main controller and nearly all parts around it doesn´t get any voltage (5 Volts completely missing). There also two parts are missing nearly the LB1649 Motor driver, one capacitor marked as C053 and one resistor marked as R048 (maybe Yamaha removed them or anyone else, maybe it is ok). Does anyone know replacement parts for the A114/C114/C116 Transistors (integrated 10K-Resistor)?

It would be very nice if someone can help me with suggestions or any voltage references of the PSU/CN025 or schematics of the PSU/Tape control board.

Thanks

Stef







I don´t know where i should start to search because i don´t know any voltages