MacVision serial adaptor is powered by a 9VAC (300 mA rating) power cube and produces +5 and +12 VDC for the digitizer (measured 5.01V and 12.14V with no load).

DB9

1 GND

2 +5VDC

3 GND

6 +12VDC

The adaptor also connects four signals (no DC power!) between Mac and MacVision:

Signal miniDIN8<->DB9

TD- 3 -->5

GND 4 <->1 and 3

RD- 5 <--9

RD+ 8 <--8

Connector ground shells do not have a DC connection to each other nor to the GND signal.