Not 100% sure, but I believe the power supply to mother brd. connection is a Molex to tinned pins connector on either the power supply brd. or mother brd.. On the 85662A display unit the tinned pin oxidizes and becomes resistive causing resistive voltage drop and heating. If the Molex white nylon start to brown then this is your problem. Cleaning both the pin and jack may solve the problem, but if it got hot enough you may have lost the spring tension on the socket side. Rebending that contact might work, or you may have to replace that spring contact. Usually it is only one pin, the one with the most current draw.
Don Bitters
