Instructable user KevinRestoreIT used extensive imagery to document the restoration of a 1978 Texas Instruments Speak & Spell educational toy, highlighting the internal technology.
The toy contained a sophisticated speech synthesiser as well as a complex power supply to operate the vacuum fluorescent display.
The power supply had evidently been damaged due to the incorrect application of a power adapter, and someone had previously attempted a repair that was unsuccessful.
Upon closer inspection, Kevin determined that a schematic for a similar power board used in an alternative version of the Speak & Spell had been reversed, resulting in the need to replace both transistors to ensure functionality.
Following the repair, the Speak & Spell operated with an AC adapter but not with batteries, and so minor adjustments were made to resolve the issue.
The startup sequence was filmed using a scope and shown in the referenced video.
