Reinventing the Swing Arm Mechanism - looking for allies! - diyAudio
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Old 8th May 2015, 08:16 AM   #1
Salar is offline Salar  Germany
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Default Reinventing the Swing Arm Mechanism - looking for allies!

Hi Folks,
Why don't we try to reinvent one the mechanically most reliable mechanisms
In CD history, the swing arm? I did a long research in what we can get today
as traverse mechanisms without satisfying results, they all would not last long.
Aim is to develop a reliable swing arm which might even give the ability for swapping the diode and its housing for future repairs.
As far as I know, Patents have run out, technology has advanced with hard disc drives, and there are still enough players out there from the eighties for reverse engineering.
I had short contact with the developer from Philips about the question why swing arms were not build any more and to him, there was not technical reason for giving up this more reliable mechanisms.
I am not a technician at all, I barely understand how a tranny works. But I have access to the mechanical aspects of building a swing arm. For developing the servo mechanisms, for finding suitable lasers and anything related to electronics, I am looking for dedicated folks from the forum.
Aim is:
Using a sturdy, brushless motor for the disc
Swing arm with reliable bearing which does not need to be serviced.
On the - so to say - tip of the arm a detachable laser diode for future servicing/replacement.
We all know working phonographs from Edison's time. This mechanism should be the phonograph of the future.
Again, I do not have the knowledge for building this. Financially, I have some limited means. But maybe as a combined effort, we could establish a new High-End transport!
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Old 8th May 2015, 10:10 AM   #2
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I have the impression that the CD format is dying. There are less and less CD stores. Media Markt closed its CD section in favor of the DVD section in my city. We have to listen to our ancient collections. The next generation listens to mp3 from online stream or from SD media, purchased online. As for me, I have a player with a swing arm mechanism, and stocked two other as donor for the same mech. So I feel safe for my life
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Old 8th May 2015, 11:41 AM   #3
Salar is offline Salar  Germany
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Hello lcsaszar,
I would propose not to discuss if CD-Players are needed or not, if CD is dying or not but to discuss
the possibility if those mechanisms can be built, to find solutions and to develop one as a group effort. My 5 cents:

I do not think that Media Markt is a good example. It has ever been a source of good music. Their customers were simply consumers of mainstream pop and Rock - easy to download. I only bought one CD there within 15 years - some Jazz they simply could not sell.

1)Especially unknown independent artists still produce CD - to them, streaming makes no profit. Also known bands complain. So for us music lovers who look for special music, CD´s will be always around.
2) My very first CD from 1983 still works like a charm - two 2,5" drives with media died after two years.
3) Even with Records: Many people buy to have something physical in their hands. The majority of record collectors simply collect - but listen to the download.
4) We could built a transport, that some national archive would be happy to use some 100 years from now
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Old 8th May 2015, 08:24 PM   #4
Mike P is offline Mike P  United Kingdom
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A very noble cause

But maybe it would be easier to lobby Philips and Sony to make some small production runs of the most sought after transports/lasers again? Such as the KSS-151A, BU1-E, CDM 1, 2, 3, 9 etc?
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Old 8th May 2015, 09:24 PM   #5
Salar is offline Salar  Germany
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I guess we could only lobby Sony if we took the CEO as hostage - and he is Japanese, thus the individual does not count.
And Philips sold consumer electronics in 2014 - we would now have to ask Gibson Guitars - no joke but they also bought Onkyo.
I was in short contact with the co-inventor of the CD and inventor of the Compact Cassette Lou Ottens - he is very old now but was so kind to tell me in one short mail that he never understood why Philips gave up producing the swing arm - I guess simply because outsourcing the production would be easier.
Long story short - no, no help from the inventors and I also assume, the production lines have already become tin cans. But maybe, some retired Philips-employees are in this forum to give some clues?
There are many, many players with swing arms still around and many service manuals available from this era thus reverse engineering would be possible,
Again as far as I have researched, patents have expired.
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Old 10th May 2015, 12:29 AM   #6
amc184 is offline amc184  New Zealand
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It's a nice idea I guess, but your list of what you'd need to do is far from complete. You've left out the tracking drive, the prism, the photodiode array, the objective and focus lenses, the focus lens suspension and drive, as well as all the electronics needed. Check out the service manual for a CD100 to see just how complex it is to develop a CD player servo without custom ASICs.

I think there are better, more feasible, ways to go. A project I considered before I lost interest in CDs was building a CD Pro equivalent for a CDM-4. There are plenty of used working CDM-4s left, the TDA8808 / TDA8809 servo chipset is still obtainable, as well as the SAA7310 decoder. The only thing that put me off was the software side, I'm a hardware guy, I didn't even know where to start to write code to control a CD mechanism with a modern microcontroller.

Oh, and I think I heard somewhere that ditching radial arm CD mechanisms had something to do with them being not as suitable for some aspect of high speed CD-ROMs, but I'm not sure.
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Old 10th May 2015, 09:47 AM   #7
Salar is offline Salar  Germany
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Ditching the swing arm in favor of straight tracking mechanisms for high speed read out makes no sense to me. As far as I understand, the swing arm does the the "long" horizontal movements, whereas the lens does the "short" horizontal movements - just like in an ordinary mechanism. If the arm did the fine movements as well, I could understand that the arm was too much mass to keep accurate tracking @20x speed.
The swing arms were very quick in accessing tracks. I guess the reason was simply easier outsourcing.
Looking through patents from 1983 up to today, the prefaces/reason for a patent was always "cutting costs/simplification! Philips had simply more suppliers for linear tracking mechanisms than their own breed swing arm
I am aware of the obstacles and how much is needed.
This is why I started the topic, to gather experts and enthusiasts
Assuming that the mechanics have to be produced/milled, could it be done with today´s parts - not leftovers from the beginning? The optical assembly will be a problem, we can´t build this, it has to be still in production.

First question : Are single-beam optical assemblies a necessety for a swing arm because of the radial path?
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Old 10th May 2015, 06:01 PM   #8
Ardee is offline Ardee  England
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I use a CD94 as a transport because it still tracks dodgy CD's better than other players. On the other hand, computer drives seem even more reliable, so a player based on a DVD drive would seem a better bet.

Don't forget that vinyl was written off too and most people do not realise how good CD can sound. There are still those of us who prefer dropping a CD in the drawer and pressing "play" to faffing around with computer menus, so good luck!

Last edited by Ardee; 10th May 2015 at 06:23 PM.
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Old 10th May 2015, 08:19 PM   #9
Salar is offline Salar  Germany
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Quote:
I use a CD94 as a transport because it still tracks dodgy CD's better than other players. On the other hand, computer drives seem even more reliable, so a player based on a DVD drive would seem a better bet.
CD94=CDM-1 swing arm, built around 1987 as far as I remember? Which DVD-Drive can cope with that?
Computer drives are not reliable - any more. Need them for work, many died. First generations were great, like one from Pioneer out of a Mac G4: Two laser units for CD/DVD, brushless disc motor, brass, steel and metal everywhere, still works after 15 years, bit the rest was built while cutting corners.

Quote:
Don't forget that vinyl was written off too and most people do not realise how good CD can sound. There are still those of us who prefer dropping a CD in the drawer and pressing "play" to faffing around with computer menus, so good luck!
So lets prepare for the hype, when people love watch the shimmer of CD´s and want to play them in standalone players.
Back to the question:
Are single beam lasers a necessity for swing arms?
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Old 10th May 2015, 09:05 PM   #10
Mike P is offline Mike P  United Kingdom
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Quote:
Originally Posted by Ardee View Post
most people do not realise how good CD can sound. There are still those of us who prefer dropping a CD in the drawer and pressing "play" to faffing around with computer menus, so good luck!
Too right!! Well said.

My own highly modified CD player had opened my eyes to how good the redbook CD format can sound.
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