Philips 70CD555 restoration project

[Daniela]

Hi @all,

some time ago I started a restoration project of my beloved Philips 70CD555. Since than I had some serious progress. From the three machines I own I've got the first one quite easily repaired (although the FM part is not working which I noted later). Just some transistors and fusable resistors replaced. Caps need to get replaced later.

Unfortunately the second unit is a real challenge since someone used it as a donor. Pretty sure about this, because every single part failed and some things got replaced or connected the wrong. Hell, even the volume potentiometer was soldered back into the device the wrong way! Not to mention that someone moved the currency potentiometer of the cd-laser but thankfully to almost zero.

So beside fixing every panel from power supply, amplifier, cassette to cd-decoder and cd-controller I run into another huge challenge since the tape deck CPU was broken. I replaced it with an AT1284P and had to disassemble how the autoreverse tape deck has to be addressed with all the motors, gears and relays. Well right now I am pretty much done with the source code and just doing some fine tuning. Every feature is back available and some additional features are implemented like a better user interface design for programming, music search for multiple tracks etc.

Besides to get repaired I exchanged all capacitors with high quality and audio capacitors. Upgraded the OpAmps and added a Bluetooth module to act as speaker for streaming. That makes so much fun and the little bastard is working absolutely great.

However, still need to replace the CDM2 because the one from a donor Philips CD150 is not sustainable. It sometimes fails to jump to tracks. Anyway, I already repaired the original CDM2. Took me a while to understand and to learn all those things. Just waiting to get a better gear for the tape mechanics before I disassemble it tagain.

And I have a third unit which is waiting to get repaired. Not getting bored the next months.

If someone is interested and want to get more details - have a look at my page...


Here are some pictures...

Kind Regards,
Daniela

 

[Brutus442]

Great work!
I've also wondered about repairing ribbon cables and whether it would be just better to replace the broken cable with wires. How do ensure that you don't bridge other circuits when soldering the ribbon?

 

[Daniela]

I would say it depends. In this case it's the part of the flex cable which is not moving. Thus it hasn't to be flexible so I soldered a little wire into the line. Otherwise a flexible cable would do the job.

The wires in the flex cable are embedded between two thin layers of plastic and you can scratch them with a sharp knife to get to the underlaying contact. In case of a CDM2 drive the wires are relatively thick, think at least 1mm with 1mm space on each side. So there is plenty of space to not scratch the other wires.The layers itself protect to bridge circuits, since it does not react on the soldering iron.

 

[caution]

I really appreciate the effort you took register the model number as a website and fill it userful content, enabling future restorers having a go at it. Well done!

 

[Daniela]

If someone is interested, I am adding videos of how to repair or/and to document my progress. I am not a professional in restoring boomboxes, but hopefully I can help someone else to repair this unique Sound Machine.

btw. did you know it was the first ever "portable" CD-Player? Portable with 10kg without battery pack which adds another 13kg. All components have a very high quality, looks like Philips tried to do their bests. However, tat the end it was very expensive and got replaced after a short time with cheaper products. Makes it a rare device.

I have 4 units and number 3 is already fixed. Only one to go... and some more pending modifications


Here's the full playlist: Youtube 70cd555 Playlist

 

[goodman]

I appreciate the work you have done to restore this interesting model.
I visited site and watched youtube videos.
I also have 2 Philips boomboxes, but they are more usual models.
Good luck with restoration of last boombox.

 

[Daniela]

Whilst repairing the Sound Machine I've got some more ideas for modifications. Currently working on Revision F of the tape deck CPU replacement and it seems that all the issues are now sorted out and it can easily replaced but just put it onto the socket instead of the old CPU. I am confident that it will be the last revision for a while - or let's say - I hope . Had issues with the clock for the CD-Player CPU which gets also powered by the same oscillator but the new CPU is running on 16MHz and the old one on 5.7MHz. Using now two D-FlipFlops to divide the clock to 4MHz. For final tests the FlipFlop is currently outside on an experimental board.

Another idea which I had was to replace the analog tape counter with a digital tape counter. Added a function to jump to position 0 or up to three stored positions. Well it is not perfect and cannot recognise the position of the tape when inserting the tape. It needs a manual reset - or automatically resets when it reaches the beginning of the tape. Basically the same functionality as my Tape Decks from Denon from the 90s which I still have.



Also restoring the tape deck if someone is interested. A lot of work... part 2 will follow

 

[caution]

Yeah, I wonder if the photo-sensor was starting to go, I'm not sure LEDs wear out? Nice that a brighter one did the trick though.
The digital tape counter is a slick idea, if it's not too integrated I could scavenge one from a standalone tape deck.
I'm also curious why the tape transport is still wonky, I hope you resolve it.

 

[goodman]

Thank you for this video.
I can't understand why Philips used plastic cassette mechanism?
Quality radio but with cheap plastic mechanism... Maybe all it's for economy...

 

[Daniela]

Unfortunately the tape counter is controlled by the new CPU and cannot be used without. Because there are no sensors at all it might not be as exact as I would like to have it, but it was a quick and better solution as the analog counter. Already have an idea how to place two photo-sensors to get more accurate results. I just need some time to work on it...

The tape transport is already working. Everything (except the soft eject function) is working fine. The new gear is great, pinch rollers refurbished and an electronic issue sorted out. Second part of the video is coming soon where I explain the issues and what I did to solve it.

I think the mechanism itself is quite good and the plastic is robust. Maybe it is because it is cheaper but Philips might thought of weight for a portable machine? Anyway, this Sound Machine was extremely expensive back in the eighties. It was the first ever portable CD-Player and the intention of Philips to use a micro controlled tape mechanism with soft touch keys was because they wanted to have the same feeling of touching buttons like on the Cd-Player (accordingly to a Philips catalogue)

However, as far as I know there are only two Philips products which used the SER1 mechanism. Think it was too expensive because when looking the mechanism of the successors - they are all easier and less complicated.

 

[Daniela]

Well, the tape mechanism can drive you crazy. There is one white lever, that holds the servo head down on fast forward/rewind and it lost its tension because the mechanism got stuck for years in the wrong position. Therefore it takes now more time to release itself and to be able to press play. I can consider this fact in the new firmware and optimise it for the particular mechanism. Finally it is back working.

On Christmas Eve my little bastard lighted up like a candle during my long term test. The smoking signals were not a good sign and I switched off immediately. However I have not found any issue, everything was working. Some days later everything failed and it was not working anymore. Seems that some components got stressed during the fire and finally failed. I had to replace two transistors and two fusable resistors on the power supply panel to get it back working. Took me another day of desperation.

Now I am running again a long time test since a couple of days and everything is working great. Think the machine and I do have a kind of love & hate relationship.

Also finished the second part of the tape mechanism repair video. Maybe someone finds this video useful. It contains an unprofessional way (for the poor wo/man) to measure wow & flutter and to set the speed. Anyway, the method was working very good, better than expected. A recorded tape on the CD555 sounds also very good on my Denon devices.

Fun fact - I had an artefact during recording from whatever source I choose. I took me about 3 days of measuring just to recognise that the signal was coming from my magnifier LED lamp.

Artefact from the LED lamp on the audio line about 37kHz ish...