KSS-272A Substitution of laser diode

Hello!
I would like to share a joyful event.
Recently I have successfully restored Philips CDM1.
It turned out to be much more complicated than I imagined.
In order to dismantle the old laser diode LT022MC, it was necessary to cut off the top of the holder in which it is installed.
To do this, it was necessary to loosen the side mounting hexagon screw and completely remove the entire structure with prisms and mirrors. In the future, this entailed great difficulties with the installation and configuration of this unit and, accordingly, the diode separately.
The diode cannot be pulled out without sawing the clip, because it is firmly glued into it. It is impossible to heat in order to pull out the diode, you can lose the mirrors and spoil everything completely.
LT022MC bought on ebay from POLIDA seller. It works so far, the flight is normal!
Moreover, the position of the trimmer resistors remained the same.
Naturally, I twisted them, but in the end they returned to their original position.
Philips CDM 1 ?????? ????????? ?????. - YouTube
 

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Congratulations. It a good job. The cut is very clean, and works.
It looks that to replace a diode laser with four phodiodes and one beam, is not as critical like the others with six photodiodes and three beams.

About Polida diodes, the very first lot of LT022mc I got was bought in polida, I bought some LT022mc and other rare LT022PD.
The LT022mc looked defectuose or fake but the LT022PD not, it works ok.
The LT022MC was thrown the rubbish bin, I did not meassured them because I did not have laser power meter at the time.
But there is something very rare with the LT022PD, if you look in the datasheet, the LT022PD has the diode position different that the LT022MC, but somehow it is not so. Is the LT022PD fake? I don't know, but it performs good, very good.
I see the LT022PD in Ebay with expensive price. Why? I don't know.
I repeat, LT022PD I bought in polida performs with optimum power, like the LT022MC. It's a bit minus higher, like the datasheet says, but the diode direction is identical like LT022MC, and it should not be so.

I've read, I don't know if it is in this forum, that early Philips CDM cd readers with single beam only needs 80uW to work properly.

Another interesting data in you cd could be to meassure the laser current. Laser current is a good data for to know the health of the laser diode.
 
Еще одна интересная информация в вашем компакт-диске может быть для измерения тока лазера. Лазерный ток - хорошие данные, чтобы узнать о исправности лазерного диода.
I will take measurements and write.
There is still something to work on ... At the next turn on, the diode stopped glowing!
Reviewing all the detachable connections, I found out that in places the dusting on the pins of the contacts was crumbling, they were bare to copper and they had to be cleaned and tinned. I am worried that the diode would not burn out. Does it look like it was in a humid and damp environment?
I continue to work)
 
I repeat, LT022PD I bought in polida performs with optimum power, like the LT022MC. It's a bit minus higher, like the datasheet says, but the diode direction is identical like LT022MC, and it should not be so.
The real LT022PD has a different pinout than the LT022MC. The LT022PD monitor diode is anode connected to GND.
It turns out that the original LT022PD can be an analogue of the ML-4402 Mitsubishi, which are much cheaper, only $ 5 here. 3mW, 785nm Laser Diode Mitsubishi ML-4402 – Meredith Instruments
They have a similar pinout. But then they will not be able to work instead of LT022MC.
I've read, I don't know if it is in this forum, that early Philips CDM cd readers with single beam only needs 80uW to work properly.
A few days ago a Marantz CD94 came to me for maintenance, made measurements, the laser power was 0.09mW and the operating current of the diode was 51.2mA. In this case, the RF level was 1.5V.
The indicators are more than excellent!
 

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Yes, ML4402 and LT022pd are totally different, the polarity are inverted.

When you do experiments, you make mistakes. If you don't do nothing, there are no mistakes, either advances.

Well, when I was experimenting with a KSS-272A, I broke the OPIC photodiode array. I connect GND to the VC pin, that is 1/2Vcc.

In this forum I read that the KSS-183A has the sme Opic that the KSS-272A. I've bought two KSS-183A for to try to repair this KSS-272A. There haven't arrived yet.

I see that the KSS-183A were used int CD Roms. It looks a KSS-190A with a KSS-272 Opic. We all know that computer CD-Roms are cheap, so and the KSS-183A are like KSS-272A and similar. This makes me think that what makes expensive the KSS-272A is the fame, the glamour or the publicital "hype".

Hi end Sony cd pickups are practically similar to cheap cd pickups. It call Sony ES, Accuphase, Wadia or an humble CD rom, the cd reader are practically equals.

About the LT022PD I have own, I still doesn't understand why the diode disposal are equal to an LT022MC.


Here are LT023Mc. I've bought here before and are serious. LT022MC has a better phase noise. The only cons is that is a bit expensive.

Here are LT023Mc. I've bought here before and are serious. LT022MC has a better phase noise. The only cons is that is a bit expensive.
 
The photodiode array of the KSS-183A laser head is not the same as that of the KSS-271A, 272A. It is like the KSS-150A, KSS-210A and the like. We'll have to make a separate RF amplifier.
The photo detector from the KSS-240A is more similar.
 
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Good Morning, 'ManoloMos' and everybody following this thread!

Firstly, thanks a lot 'ManoloMos' for sharing your experience in such details. I have read through this very often since I am seeking for a way yo replace the laser diode in a Technics SOAD70A pickup. With all the information from here, I built some test/alignment setup/rig (of course, inspired by your work), and I have a feeling I am very close.

I have a few questions and was wondering if this would be OK to discuss here.

Thanks in advance and greeting from the Netherlands!
Andreas
 

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Whoah! This looks interesting! We should also contemplate to leave the "Replace the original laser diode" route and start to talk how to implement modern laser diodes.
This means modification of the APC. Adaptors look like this:
5.6mm to 9mm Laser Diode Case Adaptor – Meredith Instruments
I bought 10 from Digikey but cannot find them any more. They can also be milled.
A provider for Diodes could be this one: http://www.qsilaser.com/download/Infra_Red/QL78F8SX_2019.pdf as they can be bought in different anode/cathode combinations
 
Thanks :) It's all based on ManoloMos' work, so a good starting point.
I am trying with an Arima laser (ADL78051TL) with a different pin out but adjusted the LD source. What puzzles me a bit - and also when looking at the specification sheet of you sent the link to - the laser current is almost half of what the original laser has. Does this mean that they are so much better nowadays .. or, they just have a more powerful but also wider beam. When looking at the sensor signals I have a certain fear that this is the case.
That would be one of my questions, why were some laser diodes classified as 'bad'? No light, no power, etc.?
Saw that you also spent quite some time with this topic :)
Another missing bit, what would be the sequence for the adjustment?
Is there also some adjustment required on the LD side? What about the cylinder lens, fine tuning ? Have seen a couple of time the pattern I would expect and was happy - but installing them into a drive was disappointing, no focus, no signal. Comparing the pick with a working and 'untouched' one does not really look different..
 
Hello. ¡Dios mio! (Ohh my god!) is what I thought when I saw the picture. The work of the hardware is flawless.
I've though to buy some Technics or Onkyo with some Nec laser pickups, but I've doing other things. Not all in life are CD players.

Well, but I've seen that you uses the cd player laser pickup circuit for to see the waves. I'd don't do this. I'd do an independent amplifier circuit, DC coupled. You can do a circuit that can be useful for other laser pickups.
With a separate laser pickup amplifier, you can amplifier the laser signal with DC component. And if there is DC component, you can rest or compensate it for to carry the out to zero volts. This is necesary for to visualize it at the oscilloscope.

Another advantage of a amplifier circuit, is to separate the laser pickup with a flex cable, so, you get a more compfortable way of to manipulate the laser pickup.


I see two kinds of laser pickups:

-. With only photodiodes. For example KSS-151a. The amplifier must be a IV amplifier.
-. With amplifier and circuits, for example like KSS-272a. A simple voltage amplifier.

Asam ask for a procedure, a sequence of adjustment.
Well...
-. Laser power at minimun.
-. Signals connected to the oscilloscope, and carried to zero volts.
-. Connect Low Frecuency Generator with DC Offset to Focus coils.
-. Try to find something at first at the E-F photodiodes.
-. When appears something, adjust photodiode place until the moment A/C=B/D diodes.
It's not easy, because the right point depends of DC-focus voltage.

I've seen on internet these Technics SOAD70A . Photodiode array looks to be attached with screws, that's good, but the position is not compfortable. You can put a plastic strip on the photodiode array with soft glue for to ease the adjustment like I've done. If you do it, you get more precision at your move.

Best regards.