A Texas Instruments Nspire I had developed an fault where it would turn on, but after a minuite or two it would freeze up. The screen would stay on, but the calculator would become completely un responsive. My initial thought was a dodgy capacitor. I took it apart and tested them with an ESR meter and they all looked fine. The calculator was making a curious humming noise whilst it was glitching which was somewhat puzzling. After a closer visual inspection I noticed that the battery compartment makes contact with the main pcb by some springy metal clips that rely on pressure to stay connected. One of these had worn down the copper coating on the pcb and was no longer making a good contact (you can see this in the bottom right of the left most image below). The simple fix was to bend it slightly to the side so it made contact with a fresh part of the pcb trace which is plenty wide enough to accomodate this. After reassembly it works just fine. I can only surmise that the contact between the metal spring and the pcb was not good enough to provide enough current for the calculator to fully work and as for the curious humming noise?
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