Roland A33 MIDI Power Supply Board

Synth Repair
1

Hello Syntaurians,

I have a question on a Roland A33 power supply board 7695002000. The D1 1N4001 protection diode was split in half and the C1 100uf cap was blown out the bottom and it only had 0.62V output Vcc. I think the Q3 BD371C transistor is failed since the regulated output is not ~5.8 VDC. There is a zener diode D5 BZX79C that I measured it’s output to be 5.8VDC. Wondering if someone has a good replacement for the BD371C NPN IC?

Thanks and I like the Syntaur YouTube videos.

2

Continuing the discussion from Roland A33 MIDI Power Supply Board:

Hey All,

Good news was able to replace the diode and capacitor with exact parts. The rectifying NPN transistor DB 371C is no longer made so found a 2N6715 with similar specs and install them all with success. Was able to power up and controller lights lit and changed state on pressing the button. Will take the next step in verification of the MIDI in and out functions to a sound module. What are any of your favorites classics as in hardware or new computer based modules?

Thanks
Wayne