Finally I reassembled everything and added a missing connector from the right speaker. In the beginning, the CD Player sometimes moved the head up and down without reading the disc. However, after some hours of playback it never happened again. Maybe there are some capacitors that need replacement? Unfortunately it seems the FM-Tuner does work since it is not possible […]
Month: July 2020
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 […]
Troubles with the slide servo relay
From time to time the slide servo relay does not switch. Till now I was not able to figure out the reason. By using the original circuit with the darlington amplifier of 7523 and 7516 the relay does not react in any way. A fun fact is that the delivered 12V are not converted into 5V (G & G1) but […]
Getting familiar with the tape deck mechanics
To be able to rewrite the code for the CPU I need to understand how the tape mechanics work. Unfortunately I was not able to get the service manual SER-1/5603 which contains the required information. Therefore, I it was necessary to do a reengineering of the mechanics. I surely disassembled the mechanics a thousand times to analyse its functions. In […]
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 […]