Dead Dead Laser Pickups - why not replacing the Diode only? - diyAudio
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Old 8th January 2010, 10:42 PM   #1
Salar is offline Salar  Germany
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Default Dead Dead Laser Pickups - why not replacing the Diode only?

Many of us still have first and second generation CD Players, built like tanks,
with linear motors, brushless disc motors, wonderful, heavy pieces of machinery and probably lasting forever - except the laser diodes.
And replacements for the pickups are no longer available or cost as much as a new player.

There are many Sony KSS-XXX Lasres out there, in many brands, with different physical dimensions, maybe different coil assemblies .
But what about the diodes?
Maybe many KSS-Lasers shared the same diode over the years, and maybe, besides the risk of static electrity, these diodes can easily be replaced?
Does anyone have information about this?
All the best,
Sal
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Old 9th January 2010, 02:13 AM   #2
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The early Sony lasers, previous to KSS150, used higher power laser diodes than KSS150 forward. Early models were rated to output 0.24mW continuously, whereas, due to improvements in photodiode arrays & whatnot, the later generation were rated to output 0.1-0.15mW. So, very definitely no compatibility between, e.g., KSS123A and KSS210.
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Old 9th January 2010, 03:42 AM   #3
mlloyd1 is offline mlloyd1  United States
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also, there is the issue of alignment of the new diode. i would imagine this requires equipment and skills that are not part of the typical diyer's toolbox.

there is a thread on here someplace where someone was planning to attempt this. not sure if he completed this successfully or not. might be worth a look ...

i agree about the old tank cd players. i miss mine, too ...

mlloyd1
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Old 9th January 2010, 03:47 AM   #4
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Thank you for posting this topic. I have been, in the past few years, wondering about this myself. Having worked in an electronics repair shop many years ago, and more recently having worked in an electro-optical communications company, I had considered replacing the laser diode in the pickups with the type used in the optical industry. Certain manufacturers of laser diodes are: Mitsubishi, Fujitsu, Furukawa, Sumitomo (I think they are called Excelight since 2006). And these are but a few. If you search long enough through their product catalogs, you could surely find a "retrofittable" laser diode.

I don't know what the typical wavelength of those KSS units is(and other types, like in my JVC XL-V330), but the choice in what is available now far surpasses what was available back then.

Typical prices of laser diodes are from 20$ to around 200$ US, and as we all know, these companies rarely, if ever, sell by the unit or sell at commercially available outlets like Digikey or Mouser.

Come to think of it, I remember seeing some Panasonic laser diodes in the digikey catalog.

Anyway, it is possible, so investigate this situation by seeing what is available to you. Let us know what you find. I've basically told you all I have thought about, and that's why I never got around to doing it, I didn't know the power, the wavelength, the pinout, etc.

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Old 9th January 2010, 07:42 AM   #5
Salar is offline Salar  Germany
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Hey, three replies in 7 hours, thank to you all!
stephensank, my KSS-123A Diode is rated at 0.4 mw max. Same with the diode in the BU-1C transport assembly I also own. (Seems like the laser pickup unit was not sold seperately) Both lasers have the same height, something can be fixed by a screw in the tube uf the BU-1C ´s laser pickup, where the optical array sits. Found nothing like a screw in the KSS-123A.

miloyd, I do not believe that mechanical alignment is needed, these were mass products. But maybe a special form factor because of very tight tolerances which is not produced any more.

Gain-wire, the wavelengh is 780nm. Did you ever open a KSS-Laser?

Another member of diyaudio, tiefbassuebertragung started this almost similar
thread:

Laser Diode Successor of SLD-104U for SONY ESPRIT KSS Series

Again, anyone living in Japan should ask all men being in their seventies if the developed laser diodes for Sony. Should be about 20 Millions, so go ahead

But seriously, any adresses, anyone to contact from the industry?

As a beginning, we could start our "rite of spring":
I have a dead KSS-123A, so I will open it and post images.
I do not expect to see a serial number on it like in "Blade Runner" , but if anyone still has a dead laser, he / she could do the same.

All the best, Salar
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Old 9th January 2010, 08:17 AM   #6
Salar is offline Salar  Germany
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Here is another useful thread in the german "hifi-Forum" about the

KSS-190A, KSS-151A, KSS-270A, KSS-271A KSS-273A, KSS-274A,
KSS-280A und KSS-281A:

Laser-Ersatz für Sony ES, Elektronik (Stereo&Surround) - HIFI-FORUM
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Old 9th January 2010, 03:12 PM   #7
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I do think that, with maybe some rare exceptions, that laser diode replacement is a process requiring some fairly critical alignment, and not merely 'drop in'. Could be wrong; never tried it myself.
As to output power, the KSS123 & those older pickups were rated 0.4mW max, but that much would fry them in short order. The rated setting on all of those was 0.24mW. On those Sony lasers, this optical power output was simply set by measuring just that. But, on some other lasers, such as the gorgeously made NEC laser used in the original Nak OMS-5/7, you had to be able to get 0.24mW AND not exceed, by much, the rated current draw to the diode(something they don't mention in the manual), or the servos won't work properly. So you need to measure optical output(Leader LPM8000, etc.) AND measure the voltage drop on the specified power feed resistor to properly set up the diode power(or diagnose a too-weak laser). So, laser diode replacement in those pickups would be a paricularly difficult proposition, since you need both proper brightness & proper current draw.
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Old 9th January 2010, 04:07 PM   #8
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Quote:
Originally Posted by Salar View Post

Again, anyone living in Japan should ask all men being in their seventies if the developed laser diodes for Sony. Should be about 20 Millions, so go ahead

But seriously, any adresses, anyone to contact from the industry?

All the best, Salar
Yes, I also have often wonderd about this: shouldn't all those engineers/technicians at those companies provide details, I mean some of them do speak english and could really help out the vintage audio community.

I have only taken the KSS lasers off the rail, but I've never taken the laser off, or maybe I don't remember. Unfortunately, the service manuals won't show the schematic of what is on the laser pickup. We'd have to make it out ourselves, to determine where we can break the connection to insert a current meter.
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Old 9th January 2010, 04:17 PM   #9
Salar is offline Salar  Germany
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Hm, looks like the first, second generation lasers and diodes seem to be a breed of their own and are no longer produced.

The butcher´s way:
Ripping out the complete Sony transport and replace it with a new / modern one. (i.e. Kss-240A based transport and electronics). Also replace/bridge the ekectronics between the command interface and digital filter with those of the new transport.
Old and new must have the same internal frequency (i,e16.9334Mhz), data format between EFM/decoder chip and digital filter has not changed over the decades, supply voltage is still 5V but I do not know about the command interface and servo control wether it is still the same kind of data format...
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Old 24th January 2010, 01:44 PM   #10
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Default Thread Overview and Gallery arround KSS Series from Sony

in this case this thread could be of interest (include a little gallery and some schematic samples):
All Diyaudio Threads about not available Optical Pickup's from Sony's KSS-Series
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