Yes probably. What model is it? I repair and restore old HP calculators. One thin about all the models from 1972 through the early 1980s that use a battery pack - do not power the calculator off the adaptor alone - these models used a working battery pack as part of the adaptor voltage "regulation" - if you power off the adaptor without the battery a much higher voltage will get into the calulator and can permanently damage it. If you dont have a working battery pack, the only way to test it is with a bench power supply set to a safe voltage. For many of these models I install a lithium battery system and USB-C charge port so we no longer have to mess around with old leaky batteries and HP's poor implementation for charging them. Some of the models that are like this are: 35, 45, 55, 65, 67, the 20-series (21, 22, 25 etc) and the 30-series (31E, 32E, 33E, 33C, 34C etc). After these, the "Pioneers" came out (11C, 15C etc) which dont use a power adaptor and are safe.