Doc uses a magnifying glass to see the time circuit control microchip while Marty looks at the repair instructions.

Doc looks at time control circuit

Doc examines the time circuit control microchip through a magnifying glass.

"This was science? / Doc held the tiny charred object in front of him, examining it as best he could in the lantern's light. Not that there was much to examine; a melted blob that didn't mean much of anything to an inventor with a background based solidly in 1955. He was perplexed, but he was thrilled as well. So much was going to change in the next thirty years, and Doc Emmett L. Brown was going to be there to see it all, and even invent something to help it along!"
—From Back to the Future Part III by Craig Shaw Gardner (quote, pages 20 and 21)
"Unbelievable, that this little piece of junk could be such a big problem."
—Doc Brown

The time circuit control microchip was a device essential to the working order of the DeLorean time machine, namely the time circuits, and was manufactured in Japan.


After the DeLorean was struck by lightning during the Hill Valley Thunderstorm in 1955, sending Dr. Emmett Brown back to 1885, the microchip shorted out, burning to a charred color. The lightning also destroyed the flying circuits fitted during the DeLorean's hover conversion in 2015 — meaning the car would never fly again.

Doc's younger self and Marty McFly found the DeLorean buried in the Delgado Mine and recovered the burned-out microchip. Working from the repair instructions and the schematic diagram placed in the car, 1955 Doc used readily available 1950s components to replace the microchip — allowing the time machine to work again, at least to reach temporal displacement. The resulting boxframe unit of 1955 components making up the new time circuit control, which included vacuum tubes, were attached by straps to the car's hood.