I just bought a Dumont 274 scope, and it seems to be missing an 8 pin plug of some sort that attaches to the back of the unit. With out it the unit won't power up because the circuit is incomplete. Can some one tell me what the part is? Also I would like to have the schematics. Thanks in advance.

: I just bought a Dumont 274 scope, and it seems to be missing an 8 pin plug of some sort that attaches to the back of the unit. With out it the unit won't power up because the circuit is incomplete. Can some one tell me what the part is? Also I would like to have the schematics. Thanks in advance.

More than likely it is just a voltage selector. Trace the connections from that connector and you will likely find that one will be a line cord connection, and the rest should be transformer taps. Verify this BEFORE proceeding. The next task is to determine which tap, when in doubt, start with the highest resistance (most windings of the smaller guage wire) ;this should be the 220/240volt tap. Fortunately tubes are more forgiving than solid state to over-voltage and short circuit conditions provided that they are not for great amounts of time, so watch the tube filaments and shut it down if they appear to be too bright, chances are in that event that you connected to the 90/95 volt tap.