Learnbydoing
New member
Nikon claims the pin out on the sync port of the 120mm medical nikkor lens with built in ring flash is a trade secret. Baloney, it is a secret only if you do not know how to use a multimeter. The pinout is as follows: center ground, inner pin 3VDC (trigger voltage used in SC-20 cable connected to PCI port on camera or hotshoe adapter), outer pin 5VDC used for SC-22 3-pin cable connected to hotshoe. I made a SC-20 replacement (this cable is ridiculously expensive if bought used from Germany or Japan) using a standard PCI sync cable ($3 in the used bin at the camera store. Note that it does not matter what is at the other end since that is cut off) and a standard 3 pin desktop computer fan connector. The middle pin on the connector is removed leaving a gap close to that between the pins of the lens sync port. Then the remaining pins are shortened by pushing them into the fan connector. Next the plastic tab is cut off to match the new pin length. Then remove the wires from the fan connector, cut off most of the PCI sync cable, strip about 3/4 inch of the cover and the wires inside. The black wire should be neutral and the white 3VDC (but you should test before soldering the wires to the top of the pins (exposed as part of the shortening process). After soldering paint all the exposed joints with liquid electrical tape, then when dry, tape the soldered area to the cable for strength. Insert the new connector so that the neutral pin is in the middle and the hot pin is innermost. Mark the neutral on the connector so polarity will be correct.
