Unit #5 and the holy grail

The last years I scanned frequently second hand shops online and sometimes offline to find spare parts or other devices. Whilst I give up to find a working device I think I learned a lot since last year to be able to repair the devices – and to be honest, four Sound Machines should be enough. That was the plan…

However, it is very hard to find the a CD555 and most of mine missed the speakers. From four only one included the speakers and I had a pair of my own machine I bough back in the eighties. For another one I bought new speakers which sound great but I am not a professional when it comes to build a nice box of wood.

All of CD555’s I have ever seen had the same issues which of course is a failure by design. The voltages provided by the power supply are too high, the TDA2030 are working above their limits, the tape deck CPU has severe issues in the source code and the tape mechanism itself fails quickly when a little white lever looses it tensions or the belt got weak. Moreover, when the tape mechanism fails the tape deck CPU hangs and since it controls the CD Player buttons the whole Sound Machine becomes useless. I thank that is the point when people through their CD555 away or, perhaps, sell it as defect. Well, that’s my turn then…

Some days ago I spotted another complete CD555 on eBay but this time with the – never seen so far – battery pack EM5555. I ordered immediately without reading the details, this was just a great chance to get my hands on this ultra rare device. Pretty sure the battery is dead after 35 years, but it can be replaced. The electronic to understand the voltages and amperes delivered by this battery pack is important.

The best thing is it also contains the user manual of the EM5555 which I already uploaded to the “Documents” folder in the download section. The battery cannot be charged with the CD555 itself, you have to remove a lid and connect a cable to a charger which was unfortunately missing in the auction. There is also a connector to plug it into the car adapter. I think I have such a car adapter from some work on the mobile home left and I will give it a try (done, but the battery is dead).

Some reverse engineering should unfold the electronics and its functions. I am going to replace the capacitors to avoid any problems. The original lead acid battery provides 12V 3Ah (240mm x 66mm x 34mm) and I ordered another lead acid battery with similar dimensions for some quick tests. I can charge it with the charger I am using for my car and later the battery can be used for other projects.

The final plan is to replace the battery with much more powerful Lithium Ionen batteries.

The Sound Machine itself of course does not work. Same issues as all the others:

• The lid of the tape deck does not open, thus the servo head is up and the white lever will probably lost its tension
• Pretty sure the belt needs replacement
• The tape deck CPU hangs and shows all segments on the LCD screen. Of course Play/Pause/Stop keys of the CD-Player are not working because of this issue
• The CDM2 itself does not read the TOC and sometimes spins the disc into the working direction – I love this
• The left audio channel is not working and it is much likely that one TDA2030 got toasted

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