Bringing a 1974 Sinclair scientific calculator back to life
When a reverse tech treasure isn’t working, the natural next step is to try to fix it. [Adam Wilson] found himself in this position when he acquired a 1974 Sinclair Cambridge Scientific calculator, and his progress with the device makes for interesting reading.
First of all, it’s something invaluable for all old Sinclair enthusiasts, it has found a solution to the original battery connectors prone to failing. A few parts stocked by RS can be used as spares, which should save a lot of Sinclairs with crispy connectors.
Saving the connectors should have fixed the calculator, but only served to reveal that it had an electronic fault. Some detective work has traced this back to the power supply, which is a small switching circuit. The 1974 chip and associated coil had both failed, which instead halted the project. A second repair or spare Cambridge Scientific was found and luckily it turned out to have a working circuit board. So [Adam] has a working calculator, and hopefully succumbs to the temptation to shoehorn into one power supply from 2022 to make the other work.
Anyone curious about this somewhat unusual calculator should take a look at our teardown.