We present our system for polygraph quality control, i.e., gain adjustment and zero correction of the amplifiers and recorders of two polygraphs that are used for monitoring blood pressure and ECG in cardiac catheterization. We examined the zero drift and frequency characteristics of the equipment, for which the gain and zero level of the amplifiers and recorders showed unstable drifting for several hours after the power supply was turned on. We devised plugs for adjusting the amplifiers and recorders. These simple devices made it easy to adjust gain and zero level, and therefore improved the quality control of the equipment in everyday practice.
