Repairing an Oltronix B602D Power Supply This is a repair and maintenance description of a 1970s linear bench power supply: the Oltronix LABPAC B602D. I bought this unit from a scrap dealer and managed to negotiate a good price. It is a classic 1970s linear laboratory power supply with two channels: 0–30 V at 1.4 A and 0–60 V at 0.7 A. The channels are fully independent, with an isolation voltage to each other and to chassis of ±500 V DC (according to the manual). It even features a “digital” voltage display. Oltronix was a Swedish company that produced high-end laboratory equipment; parts of the company still exist today and are based in the Netherlands. There is also a similar three-channel model, the B603D, which includes an additional 6 V supply. I opened the unit and cleaned out some dust before powering it on. “Take it apart,” as Dave Jones says. Internally, it looked reasonably good. On power-up, the 0–30 V channel worked fine, but the 0–60 V channel did not. I then...