Dead Laser Pickups - why not replacing the Diode only?

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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
 
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.
 
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
 
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.:confused:

gain-wire
 
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:

http://www.diyaudio.com/forums/digi...uccessor-sld-104u-sony-esprit-kss-series.html

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 :D

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
 
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.
 
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 :D

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.
 
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...
 
One laser assembly that no one ever mentioned is KSS-100A (from CDP-501es CD player) and that one is causing problem to me. I did put some questions about it on another thread. SALAR, have you managed to do anything in regards to replace diode in laser assembly?
 
I've never seen a KSS-100 laser diode get weak or die. However, I have seen a great many KSS-100's that have had their focus and/or tracking coils melted down by the STK6922 final drive hybrid chip going bad, which was a very, very common failure in the CDP-101/etc. If you happen to have a bad laser diode, but good coils(the plastic cover on top will show heat damage if they'd been burned), just about the only option is to find a player with melted coils & carefully transfer your pickup's top half to the other's very likely healthy lower half.
 
I've never seen a KSS-100 laser diode get weak or die. However, I have seen a great many KSS-100's that have had their focus and/or tracking coils melted down by the STK6922 final drive hybrid chip going bad, which was a very, very common failure in the CDP-101/etc. If you happen to have a bad laser diode, but good coils(the plastic cover on top will show heat damage if they'd been burned), just about the only option is to find a player with melted coils & carefully transfer your pickup's top half to the other's very likely healthy lower half.

Thanks stephensank; one "small" problem is that there are not as many CDP-501 units as there are in your country. I checked e-bay, and all results came from USA.

I did try to measure coils, reading was 9 Ohms; would that be OK value?
 
Yes, I agree with that, not sure if they would listen to us,lol... But I had some POSITIVE results. I disassembled head assembly, was able to have a look at photo diode, but didn't take laser diode out. Coils look fine, no trace of burning. Then I put everything back together and guess what - it WORK. Focus coils move lens up and down, and laser lit for a second and the decays. Before, disc was spinning like crazy, now it does not spin at all, just tray come out as disc was not detected. Maybe I should re-install STK6922 back again, tracking drive may be at fault...I will check that.
 
I have attached two pictures of head assembly...
 

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...in addition to above, I did install brand new STK6922, and it started to get hot; that may point to shorted coils. Strangely, how come both would measure exactly the same? So, perhaps someone knows what is exact resistance of coils?
Hi Tomom,

To (belatedly) answer your questions about focus and tracking coil resistance, I have measured them at 9.3-ohms and 8.3-ohms, respectively, in my working CDP-101. So your measurements show that yours are okay. -- Steve L.
 
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