I am trying to revive an old (and well-loved) analog phono preamp which has a PC Game Port for power supply. Since PCs with game ports are ancient history, I bought a USB-to-D15 adaptor cable. However, I checked it with a voltmeter and it does not provide +5V and GND on the standard game-port pins: it has -12V on some pins that should be +5V. Before I attempt to modify it, can anyone tell me what pinout the preamp requires? Especially, which pins does it use for +5V, GND and any other essential signals?
If it’s possible to obtain a schematic for this aged preamp, that would be even better!
Thanks,
Bob