Heathkit IT-28 Capacitor Checker Repair & Restoration

These units were sold as kits to be built around 1968. I didn’t know much about the unit so before powering it on I opened it up for an inspection. It was filthy! After cleaning the terminals and DeoxIT’ing the switches and knobs I powered it on for the first time and the Magic Eye Tube lit right up, green and bright.

Unfortunately, I had no voltage on the output in any of the Leakage Switch positions. That turned out to be a wide-open 22K resistor. After changing out that resistor out along with a dozen others that were out of tolerance, along with a handful of old paper capacitors, I had good voltage at the output terminals in every position, from 3VDC to 600VDC.

A quick calibration later and I was able to measure resistor and capacitor values, check capacitors for leakage against their voltage rating, as well as use the EXT STD input to determine the values of “unknown” resistors.

This project was a success (not always the case!), and what a beauty of a unit.