I have tested the new CPU replacement board outside with a 12V supply. When finally mounting it to the uProc board and used the 6.4V supply of the board I run into one issue. The clock signal for the CD-CPU should be 5.8MHz but was flat. One issue have been the two capacitors I was using for the 7805 to […]
Category: μ-Proc Panel
A sound machine full of miracles
The last days I designed the PCB to replace the original tape deck CPU with the ATmega1284P. After ordering the PCB I decided to run the hardware self-check of the CPU – the circuit can be found in the datasheet – to evaluate what part of the CPU is broken. Since I have not had a 10MΩ resistor I had […]
Replacing the CPU internal resonator for the clock speed
LThe tape deck CPU generates the 5.3MHz which are also used by the CD CPU. This it is necessary to keep the resonator and find a replacement in the final circuit. During the first tests I used the old CPU just to generate the required clock speed. However, it can easily replaced by an inverter gate in a 74×04 logic […]
Writing the LCD driver
First step of replacing the tape deck CPU is to write a driver for the LCD display to be able to see what is going on. The display consist of two MM5452N, serial lcd drivers which are still available nowadays. Checking the display is also a good change to proof if the hardware is working and if that may caused […]
Replacing the tape deck CPU
As the analysis has shown the tape deck CPU is broken and I am going to replace it with a modern 8-Bit Risc CPU, the Arduino. Since the tape deck CPU controls the Play/Stop/Pause buttons of the CD-Player I get, in the first step, the keyboard working. To get the pressed buttons a matrix of eight output and three input […]