Doesn't the plus need a resister soldered into place somewhere to provide termination power?
Edit: apparently a diode and a resistor, according to techknight
https://68kmla.org/forums/index.php?/topic/17130-scsi-ports-not-working-on-3-mac-pluss-confused/&do=findComment&comment=169787
Edit: apparently a diode and a resistor, according to techknight
https://68kmla.org/forums/index.php?/topic/17130-scsi-ports-not-working-on-3-mac-pluss-confused/&do=findComment&comment=169787