The relay selects whether a flat of triangular pattern is applied to the wires. C2 NEG gives DC Test Pattern, POS gives the Triangular Pattern. In addition to these functions, the control of the Vertical Integrator Gain is in this device. In field C1 ON for low gain and OFF for high gain. As a tip toward avoiding some confusion when starting up either IPM or attempting to troubleshoot a problem it is often wise to check and set the settings on some of the above devices before doing anything further.
Problems can often be the result of some change in settings that goes unnoticed.
The list of suggested settings below should give a good starting point. Note that these commands should actually be sent and it should be verified that the Computer is actually changing them.