Robotics Education & Competition Foundation
Inspiring students, one robot at a time.

Bye Bye Bye Boombox


Entry ID #: 2245
Created: Tue, Jan 12, 2016 12:19 PM

VEX Team 8390 Texas Instruments Online Challenge One teacher's trash is a robotics student's treasure! We acquired a 1990's-style boombox — an Emerson Model PD6810 Portable CD Player with scratched Nirvana CD inside — out of e-waste and disassembled it. Rather than taking a broad survey of all the electronics, we identified and learned about the functions of components on the main PCB since it is the control hub of the CD player. The one-sided circuit board contained three integrated circuits, a doughnut-shaped (aka toroidal) inductor, many resistors, 10 green polyester film capacitors, 26 orange ceramic capacitors, 16 blue electrolytic capacitors (one of which was leaking), a few connectors, and a heat sink. While no Texas Instruments components were found, the circuit board (valued at $278.95 on eBay!) included a Toshiba Single-Chip CD Processor (model TC94A29FAG), a Toshiba integrated circuit (model TA2157FNG), and a Silan Microelectronics integrated circuit (model SA1469PH). By researching manufacturer data sheets, we found that TC94A29FAG is a CMOS digital IC that translates analog information into digital information and back using A-D and D-A converters. It has four clocks, allowing the IC to interface with multiple components. This chip contains a 4-bit microcontroller and has 64 pins for input and output, power supply, and clock inputs. Toshiba TA2157FNG is a 24-pin chip that amplifies radio signals and interacts with the laser to read the CD by translating reception of reflected light from the CD to the speaker through the A-D and D-A converters. The Silan Microelectronics chip is a 28-pin motor driver that includes amplifiers and an internal thermal shutdown circuit to mute output in the event of a short circuit. Having zero prior knowledge of what a PCB is about, this machine opened up an entirely new world of electronics to us; however, sadly, it will never again play “Smells Like Teen Spirit."


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