The ornamental design for a volt-ohm-ammeter, as shown and described.
FIG. 1 is a top plan view of a volt-ohm-ammeter, showing my new design.
FIG. 2 is a front elevational view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a left side elevational view thereof;
FIG. 6 is a rear elevational view thereof;
FIG. 7 is a reference front elevational view thereof in use; and,
FIG. 8 is a top and right front perspective view thereof.
The broken line showing of a circle and indicia are included for the purpose of illustrating non-claimed subject matter and forms no part of the claimed design.