Microvision

The manufacturing process used to create the Microvision's LCD was primitive by modern standards. Poor sealing and impurities introduced during manufacture has resulted in the condition known as screen rot. The liquid crystal spontaneously leaks and permanently darkens, resulting in a game unit that still plays but is unable to properly draw the screen. While extreme heat (such as resulting from leaving the unit in the sun) which can instantly destroy the screen can be avoided, there is nothing that can be done to prevent screen rot in most Microvision systems.[9]

A major design problem on early units involves the fact that the microprocessor (which is inside the top of each cartridge) lacks ESD protection and is directly connected to the copper pins which normally connect the cartridge to the Microvision unit. If the user opens the protective sliding door that covers the pins, the processor can be exposed to any electric charge the user has built up. If the user has built up a substantial charge, the discharge can jump around the door's edge or pass through the door itself (dielectric breakdown). The low-voltage integrated circuit inside the cartridge is extremely ESD sensitive, and can be destroyed by an event of only a few dozen volts which cannot even be felt by the person, delivering a fatal shock to the game unit. This phenomenon was described in detail by John Elder Robison (a former Milton Bradley engineer) in his book Look Me in the Eye; Robinson described the issue as having been a significant enough issue during the 1979 holiday season (with up to 60% of units being returned as defective) that it resulted in significant panic among Milton Bradley staff and required extensive modifications to both later Microvision units and Microvision factories (the former being of his own design) to better dispel stray static charges.[10]

The Microvision unit had a twelve-button keypad, with the switches buried under a thick layer of flexible plastic. To align the user's fingers with the hidden buttons, the cartridges had cutouts in their bottom (over the keypad). As different games required different button functions, the cutouts were covered with a thin printed piece of plastic, which identified the buttons' functions in that game. The problem with this design is that pressing on the buttons stretched the printed plastic, resulting in the thin material stretching and eventually tearing. Having long fingernails exacerbated the condition. Many of the initial games were programmed to give feedback of the keypress when the key was released instead of when the key was pressed. As a result, users may press on the keypad harder because they are not being provided with any feedback that the key has been pressed. This resulted from a keypad used for prototyping being different from the production keypad; the prototyping keypad had tactile feedback upon key pressing that the production units lacked.