Hi Stew,
I may know of another great AC motor controller you might be able to use. I assume you have some form of speed feedback on your phono motor or platter?
If you look at the service manual for the Revox A-77, capstan motor controller. That runs off the mains transformer and is controlled with a series resistance. It is quite a good servo motor setup. I love the simplicity of it. They stick a power transistor in a bridge rectifier in series with the motor and AC voltage supply. The NPN transistor is connected collector to the positive output of the bridge and the emitter to the negative output. So the transistor is the load for the bridge.
As the transistor is turned on harder, the motor spins faster. It is capable of excellent regulation. Ever hear that the A-77 has speed stability problems? Me neither.
I'm a little hazy on the details, but the manual will reveal all their secrets. You even have an application circuit that is tried and true. Sound interesting?
The KSS-240A pickups were laughed at at first, but now they are a sign of quality and the ability to be repaired. My greatly loved Denon DCD-S10 uses the same head / transport and has been very reliable. The same head is used in the Denon / Carver / Adcom 5 disc carousel changer and is very reliable in those as well. I have three examples of that head / transport that have all been very reliable and decent performers. What more can I say? It should be a good machine.
Tell me, what D/A converter does that use? If its a BB D/A, it will be good sounding. If its a Sony pulse type, then eh. It will play reliably and sound okay.
-Chris
I may know of another great AC motor controller you might be able to use. I assume you have some form of speed feedback on your phono motor or platter?
If you look at the service manual for the Revox A-77, capstan motor controller. That runs off the mains transformer and is controlled with a series resistance. It is quite a good servo motor setup. I love the simplicity of it. They stick a power transistor in a bridge rectifier in series with the motor and AC voltage supply. The NPN transistor is connected collector to the positive output of the bridge and the emitter to the negative output. So the transistor is the load for the bridge.
As the transistor is turned on harder, the motor spins faster. It is capable of excellent regulation. Ever hear that the A-77 has speed stability problems? Me neither.I'm a little hazy on the details, but the manual will reveal all their secrets. You even have an application circuit that is tried and true. Sound interesting?
The KSS-240A pickups were laughed at at first, but now they are a sign of quality and the ability to be repaired. My greatly loved Denon DCD-S10 uses the same head / transport and has been very reliable. The same head is used in the Denon / Carver / Adcom 5 disc carousel changer and is very reliable in those as well. I have three examples of that head / transport that have all been very reliable and decent performers. What more can I say? It should be a good machine.
Tell me, what D/A converter does that use? If its a BB D/A, it will be good sounding. If its a Sony pulse type, then eh. It will play reliably and sound okay.
-Chris
Hi Salar,
Yes, no problem unless there are adjustments or test points for servicing. You can also have it mount above or below the main PCB, just hing the one on the top so you can service it.
If you are worried about possible RFI interference, just place a metallic plate between the PCBs. Not a real big problem. Fasten the plate to the board that is generating the RFI.
-Chris
Yes, no problem unless there are adjustments or test points for servicing. You can also have it mount above or below the main PCB, just hing the one on the top so you can service it.
If you are worried about possible RFI interference, just place a metallic plate between the PCBs. Not a real big problem. Fasten the plate to the board that is generating the RFI.
-Chris
Hi,
I have read almost the entire thread, which is very informative, thankyou. I fully understand the no turntable argument, but as an analog mechanical type person, ignoring reading TOCs and skipping between tracks for the sake of a theoretical mind exercise, high mass turntable looked at from the other direction, the DAC wants a constant stream of data at regular intervals. Over the short term the rpm of the CD is effectively constant as the "grooves" are co close together the circumference is hardly increasing between rotations. Surly allowing for a constant flow in to the FIFO would be a matter of tuning the motor servo slower, unless the motor actually tracks disk eccentricity and the buffer isn’t big enough to cope? one would think that the data would flow at a steady rate from the disk in and out of the fifo. or am I missing something?
I think the vibration referred to maybe slightly unflat CDs that appear to "vibrate" when rotating fast. I can't help thinking a turntable ought to help with that.... but it may not.
I have been thinking about a transport on and off for some time, assuming it would be fairly straight forward, but now see that the adjustments and tuning are the "interesting" bits.
The adjustments aim is to get the CD square under the lens laser so the beam can shine out and be reflected straight back?
Adjustments would then be 2 axises of tilt and height for the CD in relation to the laser. if these would be integrated into the motor mounting the amount of travel should not be too great, and fine tuning could be accomplished using some grub screw type arrangement, all nicely out of the way of moving parts! I actually think this would be quite enjoyable to set up, a bit like tuning in an old shortwave radio, trying to get the best signal. But I have never tried one!!!!!!!!!
my 2 pence worth.
I have read almost the entire thread, which is very informative, thankyou. I fully understand the no turntable argument, but as an analog mechanical type person, ignoring reading TOCs and skipping between tracks for the sake of a theoretical mind exercise, high mass turntable looked at from the other direction, the DAC wants a constant stream of data at regular intervals. Over the short term the rpm of the CD is effectively constant as the "grooves" are co close together the circumference is hardly increasing between rotations. Surly allowing for a constant flow in to the FIFO would be a matter of tuning the motor servo slower, unless the motor actually tracks disk eccentricity and the buffer isn’t big enough to cope? one would think that the data would flow at a steady rate from the disk in and out of the fifo. or am I missing something?
I think the vibration referred to maybe slightly unflat CDs that appear to "vibrate" when rotating fast. I can't help thinking a turntable ought to help with that.... but it may not.
I have been thinking about a transport on and off for some time, assuming it would be fairly straight forward, but now see that the adjustments and tuning are the "interesting" bits.
The adjustments aim is to get the CD square under the lens laser so the beam can shine out and be reflected straight back?
Adjustments would then be 2 axises of tilt and height for the CD in relation to the laser. if these would be integrated into the motor mounting the amount of travel should not be too great, and fine tuning could be accomplished using some grub screw type arrangement, all nicely out of the way of moving parts! I actually think this would be quite enjoyable to set up, a bit like tuning in an old shortwave radio, trying to get the best signal. But I have never tried one!!!!!!!!!
my 2 pence worth.
ThanksI have subscribed to this thread, Will watch with keen interest
But I´ll have to emphasize this agai.:
The prototype will be solely based on existing, parts, sme of them 30 years
old from times when mechaniocal durability was king.
Nothing from scratch yet.
Aim of this thread is to get engeneers into the boat and built a
prototype from scratch - then even explore the possibilites of mass production.
Besides durability, reparability is the main Goal. Those drives should work
for decades, the diodes being replacable. Long way to go.
All the best,
Salar
I just read though the last half dozen pages after being away for a while.
Salar and others have put a lot of thought and effort into this, and I thank you all for the entertaining ride along.
I've learned a lot along the way, but forgotten much more.
Just an observer, please keep up the good work.
Salar and others have put a lot of thought and effort into this, and I thank you all for the entertaining ride along.
I've learned a lot along the way, but forgotten much more.
Just an observer, please keep up the good work.
Project is still going on. Some drawbacks as I focused on Philips swing arms for entire 2017.
One main goal besides building something from scratch is that I can at least handle any problem related to the mechanism which is the blueprint for the rebuild.
If there will be no rebuild at all, at least there should be solutions for keeping those old Players running by replacing diodes / photodiodes or coils.
Because I could not handle the alignment of the diffraction grating, I switched over to the Philips swing arm which does not have a diffraction grating.
But after the long time mentioned above and after learning how to repair many faults I stumbled over the problem that one swing arm I own
does not read discs despite everything is electronically perfect and also mechanical alignment seems to be in the sweet spot.
The next step would be to replace the roller bearings of a swing arm because micro movements are suppressed.
But this cannot be done easily as one bearing is pressed or even weldered to a thin plate.
So I switched back to Sony´s linear mechs in December...
The story continues but still has not left the stage
where simply old electronics will be used almost unaltered...
Still looking for folks with knowledge to join the boat!
One main goal besides building something from scratch is that I can at least handle any problem related to the mechanism which is the blueprint for the rebuild.
If there will be no rebuild at all, at least there should be solutions for keeping those old Players running by replacing diodes / photodiodes or coils.
Because I could not handle the alignment of the diffraction grating, I switched over to the Philips swing arm which does not have a diffraction grating.
But after the long time mentioned above and after learning how to repair many faults I stumbled over the problem that one swing arm I own
does not read discs despite everything is electronically perfect and also mechanical alignment seems to be in the sweet spot.
The next step would be to replace the roller bearings of a swing arm because micro movements are suppressed.
But this cannot be done easily as one bearing is pressed or even weldered to a thin plate.
So I switched back to Sony´s linear mechs in December...
The story continues but still has not left the stage
where simply old electronics will be used almost unaltered...
Still looking for folks with knowledge to join the boat!
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Gents ... regard this being a last call:
With my limited knowledge, I will never be able to built a CD-mech from scratch.
So please, anyone with profound knowledge, join the boat and the effort.
Anyone who knows people who developed the technolology or were involved
in laser production please join this project.
The biggest problem now is that anyone says CD is dead - but in fact CD will be around for the next 100 years but totay´s cheap plastic mechs will not. So there is a benefit to think NOW of designing a durable and repairable mechanism and not to wait until first hand knowledge has literally died out. Also, with the trade of our data and scandals coming from that, (see facebook) there will be more and more people recovering the benefit in buying analoge - from record stores or thrift shops. Think about that...
With my limited knowledge, I will never be able to built a CD-mech from scratch.
So please, anyone with profound knowledge, join the boat and the effort.
Anyone who knows people who developed the technolology or were involved
in laser production please join this project.
The biggest problem now is that anyone says CD is dead - but in fact CD will be around for the next 100 years but totay´s cheap plastic mechs will not. So there is a benefit to think NOW of designing a durable and repairable mechanism and not to wait until first hand knowledge has literally died out. Also, with the trade of our data and scandals coming from that, (see facebook) there will be more and more people recovering the benefit in buying analoge - from record stores or thrift shops. Think about that...
Hi Chris,
the prototype still consists of nothing more than a CDM-1 or BU-1 in a self designed cabinet (which still has to be milled).
The project did not evolve to a point where people with real knowledge about laser, optics, servo design joined in
to reverse enegneer those mechanisms...
I cannot stress this enough: Building such a transport from scratch could also be a chance to built something sustainable:
A transport that can be aligned and repaired, even the diodes and photosensors could be replaced, the servo system could be based
on existing opamps and parts - the very first mechs were very close to that goal, check the service manuals of a CDM-1, CDP-101, XR-Z70 - and many of those players/units still work today!
the prototype still consists of nothing more than a CDM-1 or BU-1 in a self designed cabinet (which still has to be milled).
The project did not evolve to a point where people with real knowledge about laser, optics, servo design joined in
to reverse enegneer those mechanisms...
I cannot stress this enough: Building such a transport from scratch could also be a chance to built something sustainable:
A transport that can be aligned and repaired, even the diodes and photosensors could be replaced, the servo system could be based
on existing opamps and parts - the very first mechs were very close to that goal, check the service manuals of a CDM-1, CDP-101, XR-Z70 - and many of those players/units still work today!
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Hi Salar,
I think that if you rolled back your expectations to maybe only the laser diode that can be replaced, you would be closer to a solution. If the pickup diode(s) ever go, the head should be scrapped or sent for rebuilding, like an MC phono cartridge. This is an extremely rare occurrence. Just work on having the laser diode be replaceable.
With the higher efficiency of modern LEDs, you would think that would spill over to laser diodes. That means you can run them at much lower currents for the same optical power out and they would then outlast the mechanical parts by a wide margin. So look into that because that alone may take the replaceable laser diode off the table.
-Chris
I think that if you rolled back your expectations to maybe only the laser diode that can be replaced, you would be closer to a solution. If the pickup diode(s) ever go, the head should be scrapped or sent for rebuilding, like an MC phono cartridge. This is an extremely rare occurrence. Just work on having the laser diode be replaceable.
With the higher efficiency of modern LEDs, you would think that would spill over to laser diodes. That means you can run them at much lower currents for the same optical power out and they would then outlast the mechanical parts by a wide margin. So look into that because that alone may take the replaceable laser diode off the table.
-Chris
I just thought that would post a link to AliExpress where I bought 2 SF-91's last summer for just over £15 pounds ($20). It looks likely the current price is very similiar.
I bought the SF-91 mechs. for spares for a Cambridge CD6 and DiscMagic.
Brand new SANYO CD laser SF 91 5/8 P mechanism optical pick up for homely CD player Bose media system car radio-in Car Radios from Automobiles & Motorcycles on Aliexpress.com | Alibaba Group
Hi Indyaudi,
thank you for you contribution but this thread is not about existing CD-mechs.
It is about building a mech from scratch, taking reliable and robust designs like the Philips swing arm as references.
And to unite experienced people with the knowledge needed to contribute to this goal.
The goal is also to be completely independend from what is offered from suppliers.
Because there are None.
You give the best example with your link :
Sanyo ceased to exist in 2011.
Their buyer Panasonic never announced CD-mechs for the OEM Market,
nor will you find them on Panasonics industrial websites. Panasonic never produced CD-Mechs for other companies, like Sony, Sanyo or Philips, nor will they.
Sanyo, Philips are gone Sony was rumored to have stopped production already two years ago.
So, your brand new Sanyo SF 91 probably least 7 years old, counterfeit or b-stock.
Again, go to any consumer electronics show in this universe: There are no suppliers for CD-and DVD mechs to be found at all.
I checked about 400 supliers at IFA in Berlin, most of then chinese or korean - None had CD-mechs to offer.
Streamunlimited, a well known austrian company founded by Philips staff to design compact disc player for many european
high-end brands (as well as Music Hall) does not offer solutions for CD-playback any more. For optical storage now need to call the staff directly.
Two years ago, everything was laid ot on the Website. Three years ago, when they were at IFA, they left thei optical sgtorage samples home.
No buyers any more.
thank you for you contribution but this thread is not about existing CD-mechs.
It is about building a mech from scratch, taking reliable and robust designs like the Philips swing arm as references.
And to unite experienced people with the knowledge needed to contribute to this goal.
The goal is also to be completely independend from what is offered from suppliers.
Because there are None.
You give the best example with your link :
Sanyo ceased to exist in 2011.
Their buyer Panasonic never announced CD-mechs for the OEM Market,
nor will you find them on Panasonics industrial websites. Panasonic never produced CD-Mechs for other companies, like Sony, Sanyo or Philips, nor will they.
Sanyo, Philips are gone Sony was rumored to have stopped production already two years ago.
So, your brand new Sanyo SF 91 probably least 7 years old, counterfeit or b-stock.
Again, go to any consumer electronics show in this universe: There are no suppliers for CD-and DVD mechs to be found at all.
I checked about 400 supliers at IFA in Berlin, most of then chinese or korean - None had CD-mechs to offer.
Streamunlimited, a well known austrian company founded by Philips staff to design compact disc player for many european
high-end brands (as well as Music Hall) does not offer solutions for CD-playback any more. For optical storage now need to call the staff directly.
Two years ago, everything was laid ot on the Website. Three years ago, when they were at IFA, they left thei optical sgtorage samples home.
No buyers any more.
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Thanks a lot,
project is still going on. I will work on a CDM-1 in the next days.
Background is that I need to clean the lens system to foreclose the possibility that the laser or photodiodes
have died; I did work on this very CDM-1 before and besides being grounded against esd , I short circiut the diode. Neverteheless after some time I did this aligent.
http://www.diyaudio.com/forums/digi...-cdm-1-swing-arm-alignment-4.html#post5020778
the CDM-1 will not read. I will take the opportunty to measure the parts and convey them into a CAD program. But I will probably have to avoid some measurements to avoid scratching the lenses with the gauge.
In the moment I am focusing on single beam mechs, as they need no diffraction grating. Examples are the very first Denons (DCD-1800, but not reliable), Philips and some Technics stuff.
The CDM seems to be promising for reverse engeneering because there is only one horizontal servo and not two (coarse and fine movement) It also looks like no one needs to think
about having a lens move horizontal and vertical inside its housing - With the CDM-1 the lens moves horizontal and the whole arm does the coarse and fine tracking - but has to cope with friction
project is still going on. I will work on a CDM-1 in the next days.
Background is that I need to clean the lens system to foreclose the possibility that the laser or photodiodes
have died; I did work on this very CDM-1 before and besides being grounded against esd , I short circiut the diode. Neverteheless after some time I did this aligent.
http://www.diyaudio.com/forums/digi...-cdm-1-swing-arm-alignment-4.html#post5020778
the CDM-1 will not read. I will take the opportunty to measure the parts and convey them into a CAD program. But I will probably have to avoid some measurements to avoid scratching the lenses with the gauge.
In the moment I am focusing on single beam mechs, as they need no diffraction grating. Examples are the very first Denons (DCD-1800, but not reliable), Philips and some Technics stuff.
The CDM seems to be promising for reverse engeneering because there is only one horizontal servo and not two (coarse and fine movement) It also looks like no one needs to think
about having a lens move horizontal and vertical inside its housing - With the CDM-1 the lens moves horizontal and the whole arm does the coarse and fine tracking - but has to cope with friction
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