Sony’s boombox series from the 80ies with a special technology for bass improvement had the strange name “DoDeCaHorn” and is probably not well known outside of Japan.
The top of the line models were CFD-700 and CFD-900. The 700 has a 5-band equalizer with mechanical sliders and a mechanical switch to change the functions to Tape, Radio, CD, AUX, that could not be operated with remote control.
On the 900 all is electronically controlled and can be operated with RC.
I started with the CFD-700 that is often available on Japan’s Yahoo auctions. I could repair it as good as possible. After that I was thinking, that I need the more sophisticated CFD-900.
At the end I had to order two devices to make one almost fully working. Those boomboxes are fully crowded with electronics and have a lot of IC’s inside. If there is something wrong, it will be difficult to repair. But luckily most problems are just related to mechanics, especially on the tape decks.
So I found out, that Sony here used some kind of grease that hardened over the time. The tape mechanism then was not movable anymore. I cleaned it with iso and used some oil to loosen everything. The tape mechanisms are not easy accessible, as on the back side is attached the pre-amp board with a lot of wires. I made a lot of pictures to bring it back to initial state. Of course also all 4 belts had to be replaced.
During my work on this device I added some additional features:
On the next pictures are some impressions of the repair process.
Some bulbs are burned
Pre-amp board on back side of tape decks
Tape decks during adding LED's
New LED's, painted the board with white color to make it brighter
FM Converter
RGB LED stripe in CD-Player
Controller for RGB LED's
The final result
Here a comparison of Display with bulbs (front) and display with LED’s (back).
Small video, showing the functions after repair:
CFD-900 Functions
The top of the line models were CFD-700 and CFD-900. The 700 has a 5-band equalizer with mechanical sliders and a mechanical switch to change the functions to Tape, Radio, CD, AUX, that could not be operated with remote control.
On the 900 all is electronically controlled and can be operated with RC.
I started with the CFD-700 that is often available on Japan’s Yahoo auctions. I could repair it as good as possible. After that I was thinking, that I need the more sophisticated CFD-900.
At the end I had to order two devices to make one almost fully working. Those boomboxes are fully crowded with electronics and have a lot of IC’s inside. If there is something wrong, it will be difficult to repair. But luckily most problems are just related to mechanics, especially on the tape decks.
So I found out, that Sony here used some kind of grease that hardened over the time. The tape mechanism then was not movable anymore. I cleaned it with iso and used some oil to loosen everything. The tape mechanisms are not easy accessible, as on the back side is attached the pre-amp board with a lot of wires. I made a lot of pictures to bring it back to initial state. Of course also all 4 belts had to be replaced.
During my work on this device I added some additional features:
- As the radio has only the Japanese FM frequency range from 76…90MHz, I built in an FM converter that shifts frequency for 10MHz and 20MHz. Now I can listen to German FM radio.
- The display is illuminated with incandescent bulbs and lights up only when attached to AC Mains. As on one display some bulbs were burned, I changed it to orange LED’s and connected them to another point on PCB, so that they work now also in battery mode.
- Furthermore I added LED’s to tape decks and the CD-Player. On CD player it is possible to change the color as there are RGB LED’s.
On the next pictures are some impressions of the repair process.
Some bulbs are burned
Pre-amp board on back side of tape decks
Tape decks during adding LED's
New LED's, painted the board with white color to make it brighter
FM Converter
RGB LED stripe in CD-Player
Controller for RGB LED's
The final result
Here a comparison of Display with bulbs (front) and display with LED’s (back).
Small video, showing the functions after repair:
CFD-900 Functions
