Purpose -The purpose of this paper is to study high-voltage interactions in polymer thick-film resistors, namely, polyvinyl chloride (PVC)-graphite thick-film resistors, and their applications in universal trimming of these resistors. Design/methodology/approach -The authors applied high voltages in the form of pulses and impulses of various pulse durations and with different amplitudes to polymer thick-film resistors and observed the variation of resistance of these resistors with high voltages. Findings -The paper finds that high voltages can be used for trimming of polymer thick-film resistors in both directions, i.e. upwards and downwards.Research limitations/implications -The research implication of this paper is that polymer thick-film resistors can be trimmed downwards or upwards practically using this method. Practical implications -The practical implications of this paper is that one can trim the polymer thick-film resistors, namely, PVC-graphite thick-film resistors, in both directions, i.e. upwards and downwards, by using this method. Originality/value -The value of the paper is in showing that high voltages can be used to trim downwards and also upwards in the case of polymer thick-film resistors. This type of trimming is called universal trimming, developed first time for polymer thick-film resistors.