Hi, I am repairing my old sound machine, a Philips 70CD555. I have three of them all showing the same issues. Pretty sure I will need professional help at some point. Unfortunately this is not going to be an easy task like a bit of cleaning because a lot of things are broken. Let me summarise: The CD is spinning returns "Error". Play/Start/Stop not working The tape deck does not show any signs of life, the lcd shows all options, lid does not open Horrible sound at startup In the meantime I know that the all those signs lead to one problem, the tape deck CPU is broken and needs to be replaced. Well, even if I could get the Motorola CPU I do not have the source code for the eprom. However, I am going to replace it with an Arduino and rewrite the code by reengineering all the other functions. Since the Play/Start/Stop buttons from the CD-Player are also controlled by the tape deck CPU I replaced the old CPU and wrote a keyboard driver for the Arduino. Finally all keys are working so I have been able to test the CD-Player. I also replaced the controller board with one of the other devices I have and it is working now. Although from time to time the head goes up and down and does not read anything. Now working on the tape deck. Learned how the mechanics are working because I wasn't able to get the service manual SER-1/5602. Right now, to control the relays with the Arduino is not working since I need to recalculate the resistors for the used darlington transistors amplifier. Seems the original CPU delivers more than 40mA on an output. Also the BA6109 reverse driver seems to be dead. Ordered a bunch of transistors for replacement and some experiments. In addition, I replaced the capacitors of the power supply and switched the transformer to 240V since all the voltages where way too high. For instance, 9V has been 13.8V during operation and things got very hot inside. Afterwards the startup sound is still there but not so aggressive and voltages are closer to what they should be. This whole recovery will take me some months, but I have time. Waiting since 33 years to find some time to get it working... Daniela
That is getting adventurous changing the processor and rewriting the software. Are you sure that all the inputs to the original processor were correct. With badly written software one incorrect input (for example caused by a faulty microswitch) could cause the whole system to hang. As a an illustration I have a modern Sony XDR100S radio CD with a faulty tuner; it won't receive anything. However, it won't boot to do anything without the tuner board fitted. I bought an identical looking tuner board, but which was sold as an upgrade to a Bose system. With that fitted it still won't boot. I guess the tuner board has to respond with a specific message that is programmed differently. Did you see my recent post http://www.stereo2go.com/forums/attachments/cds-1988-jpg.24230/ If you don't know, Magnavox was one of the brand names Philips used in North America as Philips was considered to be too close to established electronics company Philco. If you could get a service manual for one of those similar looking units it might give you some clues.
Have you tried https://www.serviceandusermanuals.com/philips.html The 70CD555 service manual is listed there. Not a site I have ever tried before but it might be worth enquiring
Hi Longman, well I checked all inputs. VSS, VDD, Reset etc. everything was fine. Even the oscillator was working at 5.3MHz - it also powers the CD-CPU However, no output pin of the CPU shows any reaction. It is also not possible to run the test program. The service manual has two pages for checking the CPU, describes all the pulse trains but none of them exists (excerpt below). I wished it would be something less adventurous. Thank you, I do have the service manuals in English and Dutch (not that I would understand but scans have a better quality) and all the data sheets. The only service manual that is missing is about the tape mechanics but I figured out how it works. Basically I have implemented all the functions - currently working in the IRQ for music search - but not stable. One relay does not switch from time to time. Might be my darlington circuit I had to replace.
I wonder if the CPUs have forgotten their programs. In the early 1990s at work we got samples of the first Altera in circuit programmable CPLDs. They seemed great, until they all forgot their programming after about a week. After that, on the board I was designing I stuck with the unplug the device and put it in a stand-alone programmer CPLDs.
Hmm, that might be possible. But then this must be general problem because I have three devices all with the same issue. I do have the data sheet of the CPU and it has a circuit to test the functions independent of the program. I will give it a try...
That is why I was trying to think of some generic problem that could have happened to all three. Unfortunately bits are far more difficult to replace than a belt.
Is anyone out there who probably has the user manual of this device? I know I have it - somewhere - but I am unable to find it. A scan would be really helpful to be able to emulate the same behaviour. During the last weeks I reengineered the tape mechanics and most of the functions are working with the new CPU but there are some questions about the behaviour of the original software. Or maybe someone with a working device could get in contact with me to check the functions? Thank you.
Hi, short update... Good news is that one of the three devices is working. Repaired CD, Cassette and power supply. Even the original tape deck CPU is working and I can figure out all the functions and necessary steps to address the tape mechanics. Unit #1 was a quite easy task compared to the second unit. Maybe it was used as a donor because almost everything is broken. Parts of the power supply and amplifier were toasted because of an over-voltage. Repaired both and they are working now. CD Player is not reading discs but will get some spare parts during the next days and I am sure I can continue soon. Have done a first PCB to replace the broken tape deck CPU with a AT1284P. Source code is already working. If you are interested into more details please have a look at my website www.70cd555.com (@admins please let me know if it is not allowed to link to pages) Here are some of the latest pictures of the progress... Replacement for tape deck CPU Unit #1 in action, should make a video
I'm very impressed. I was going to ask if you designed the green PCB yourself but can see from the logo that you did. I think I would have given up a long time ago, although doing this sort of thing is a bit too much like my day job. What did / do you do to learn such skills ? Having looked it up, I am impressed by your KMoon Signal generator. Chinese test equipment really has been a game changer for the hobbyist. One of my college projects was a purely analogue signal generator. The components for that probably cost as much back in 1979 as your ready made DDS generator costs today. Two other questions. What oscilloscope are you using and what PCB package did you use ? Back in the 1980s at work I bought (using the companies money) a Philips four beam 100MHz oscilloscope that cost about £3000 new, and designed PCBs on a Racal Redac ECAD system that cost £30000 (more than my house back then). Nowadays I just seem to write specifications and do VHDL code for FPGAs.
Hi Longman, A long, long time ago I visited a higher school of engineering for electronics. Called "matriculation" in Austria. But never got a job in this field and I changed to software development. Later on I studied business informatics and business administration. Software development is what I am still doing, leading a team and projects on a worldwide scale for the market leader in pneumatics. The Signal Generator is quite cheap. Pretty sure it is not as accurate as the expensive ones but for private use it is very useful. You can find it on Amazon for about 120€. In this case I used it to repair the amplifier and tuner. The oscilloscope is a Rigol DS1054. It has four channels and can measure up to 50MHz which is more than enough. It also has some great features like calculate FFT and display I2C commands. Something we dreamed of in the last century. They are really cheap nowadays. Can remember how expensive and complicated they were. For the PCB I used Fritzing but I am not happy with it - it's too rudimental. In the meantime I learned to use kiCAD. Offers much more possibilities and is more professional. There are a lot of services out there to whom you can send your project files and you will get the final PCB in a professional style for less than 30 bugs in a couple of days. FPGAs are very interesting but never had time to dive into the topic. Of course it is a lot of effort to bring this thing back to life and from a financial perspective it is far away to be reasonable. But I love this machine and it is a kind of hobby to repair them... kr/Daniela
I need to tell you that the hardest thing to repair this machine is the cat... Ever stepped on an IC? Leaves nice patterns on your foot. Lego is for beginners. btw. unit #2 is completely working. Finished the source code for the tape deck, added some more options and optimised the user interface a little bit. Should make a video... Currently assembling the unit if I ever find all the parts.
Sitting here listening to & recording music onto tape and doing the last optimisations on the source code for the tape CPU. Of course music from the eighties. Working so great - I am probably the happiest person alive. Never thought I can bring it back to life after so many years. Wonderful sound, smooth operating. This device is really a masterpiece. And now it got even more features added. e.g. waiting for a DC/DC converter to activate the bluetooth module. Ordered new Audio CDs (Soundtrack from Guardians of the Galaxy) - I really have forgotten how bloody stupid it is to open up the plastic bag of a CD
Your cat is better trained than our three. I'm still waiting for them to finish installing my satellite dish Tiny (one the left) was up on my lap ten minutes ago. At least he didn't do his usual trick of lying on my computer keyboard. p.s I hope you have never unplugged an IC from it's socket into your thumb. I have done that a few times when I was regularly changing ICs at work.
Haha, cute. They look like they have a diabolic plan. I guess they want to activate it and use it to rule the world. No, never tried to put an IC into my thumb. But between the lines you want to tell me I shouldn't try this, right Anyway, I am now finished with unit 2. Also updated my replacement pcb to rev.B since I had some mistakes in the first. Another idea is to use a timer as a clock for the CD-CPU, but need to test it. Panels are ordered lets wait until I get them. For the gear of the tape mechanics I think about getting a resin printer since I am not 100% convinced from the filament. The motor slows down and sometimes stop on rewind. Not always but happens. Has anyone experience with printing such gears with a resin printer? The firmware of my CPU is finished and working. It also adds some new features to the tape deck (of course only interesting for those who own the sound machine or are familiar with it): Changed behaviour: Music search supports up to 9 tracks when pressing next/previous. Original behaviour: only next or previous track Programming works differently. The tape rewinds when you start the program, not before. Also side B is supported! Therefore, up to 40 tracks can be programmed. Original behaviour: 20 tracks and only one side The button “record” can be used to enable or disable record mode. In addition, the Stop key always disables the record mode. Original behaviour: Record button only activates record mode In Record-Mode the reverse key only allows repeat mode A->B and does not show other reverse modes New features: When pressing record and the tape reader recognises the tape is at the very beginning it moves forward until the tape really starts. Avoids to record music on the non magnetic part of the tape. During this procedure record is blinking In case of rewind, when the tape moves to the very end it moves back forward a when on a splice of the tape Auto-Record mode shows the number of recorded tracks. Always wondered why Philips was not using the two digits and always displays 00? For those you want to read more: LINK Also added a bluetooth module to act as a speaker. Welcome to the 21st century With the new caps and OpAmps the sound is quite good. Oh and I found the user manual and the original box of the machine I bought back in 1987. There is already a scan of the English and German chapters of the user manual on my page available. Well both are not in the best condition.
This is the most advanced restoration I have ever seen, truly AMAZING!!! Hopefully someone will add to the list, but the only restoration of this caliber (by sheer intent and determination, not programming skills) was published in Boomboxery for Panasonic RX-5350: Fixing a legend..... and also by one of our own, Debbie @Deb64 for WM-D6 at Tapeheads forum: Speed Control IC for WM-D6 @Daniela , many thanks for the tip: I will never-ever even look at CD555! Reading through your blog is enough fun for me, and if I ever decide to torture myself, I will fix another WM-D6
Daniela's blog is like those good books that you really can't help but to read from start to finish at once ( and then reread). The repair progress bars at the Status section is a brilliant idea ! Looking forward for Unit 3 to start . Something not to be overlooked Daniela is the first person in the world , to my knowledge , that did a soft mod to a three piecer/boombox ! :
Had been out of order for a while because of a bacteria infection. Not Covid - hope you are all healthy and safe! @Jorge, you should get one! It is an amazing device and I would be very happy to help. @Machaneus: Thank you, too much flowers. I am pretty sure someone else has done this already The last days I was not able to write anything but it is getting better now. And I used the time to record some videos of the project. Starting with a first introduction. Not sure if this is from any help or interesting, we will see. In the next episode I am going to show the differences between the new and old CPU/Firmware and the new features/modifications.
Another day, another video. Already started with unit 3. This is going to be an easy task In other words - boring lol Also added a teardown video if someone might be interested...
some news... CPU replacement revision B is working and now really plug and play - no need to change anything on the board. Before, I had to use a piggyback for the CD-CPU clock. The only drawback is that I had to reduce the CD CPU clock from 5.8MHz to 1MHz because of timing. However, the CPU idles most of the time. Wished I would have had 5.8MHz in my Commodore 64 back those days! Link to more details: https://70cd555.com/modification-of-cassette-cpu-rev-b-is-working/ Also some new videos... if someone is interested... (probably not lol) Please let me know if I am a pain in the neck.
