My first Sinclair calculator to add to the collection, a Sinclair Cambridge from 1973, as with most things from Ebay this arrived in very grubby condition and in a dubious ‘not tested’ state. The first thing I noticed was that someone had tried to ‘fix’ the battery terminals, which had corroded due to leaking batteries. After a bit of terminal cleaning and rebuilding I tried to turn it on – a little temperamental but a single ‘0’ was displayed…. a good sign. Or so I thought. “1+5 = 343656”, Hmmm, my maths might be a little rusty but that isn’t the correct answer. The display also kept flickering on and off.
On closer inspection I noticed that the previous ‘fixer’ had been fixing something on the main chip as well, solder was bridging a number of the chip legs – how did that happen?
I removed the solder bridge and replaced the two capacitors.
Guess what – “1+5=6”, well that was an easy fix. Following reassembly and cleaning I now have a fine, working, example of the Sinclair Cambridge 🙂