Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

KSS-272A Substitution of laser diode
KSS-272A Substitution of laser diode
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 21st June 2020, 07:02 PM   #1
ManoloMos is offline ManoloMos  Spain
diyAudio Member
 
Join Date: Dec 2019
Location: Canary Islands
Default KSS-272A Substitution of laser diode

Hello. I've tried to know how to change the laser diodes in the CDs laser pickup and today finally I've changed a diode in a KSS-272A successfully.

As in other thread about the KSS-190A I said, I tried to change the diode laser and to adjust it, but it don't work. It works in KSS-121A and BU-1C, but no in KSS-272A.

For to adjust the KSS-272A, and others I suppose, you have to adjust the position of the Photodiode array IC. This is main trick.

This is the process.

1) Remove the diode, remove all the glue, clean it, blow with air under pressure.
2) Then place the new diode, type M (both diodes with common cathode), I put a Rohm RLD-78MA. Put glue, I used glue of two components. Wait until the glue is dry.
3) I change all potentiometers. Original are right, but are very hard for to manipulate. All are 2k2.
4) In the photodiode array Ic, remove the glue
5) Place the laser pickup in the mirror, with the 2mm pcb with a hole for the light to the laser.
As I said in the other thread, you force the laser ouput, extend the laser cable and cut the focus conection. In focus conection you conect a power supply(no more than 1 volt) and a low frequency generator.
6) Conect the A-B-C-D-E-F to a signal amplificator, six amplifiers in fact, and conect it to the oscilloscopes.
7) Place a piece of plastic in the fotodiode array with soft glue. It is used for to grab the fotodiode array with care.
8) Conect all, power up the CD, and find the signal. The first signal in appearing are the E-F signals. They are very usefully for to find the signal. In my case the power supply is 700mvdc and the signal generator between 21 or 23hz and between -4dbm or 0dbm.
9) Then you try to find the point like in the pictures appears, where A and C and B and D must be in phase, but 180 disphased between AB and CD. You must build a device like mine with a screew for to lock wheh yo have the right signal.
10) The signal is right and the screw lock the photodiode array for it can't be moved. Now you put glue where you retired the original factory blue. Wait until the glue is dry.
11) Now, without the screw lock the photodiode, you must confirm the signal is right.
12) Install the laser pickup and and ajust power laser and focus. And yes, it's difficult, for this in the point 3 I changed the potentiometers.

The laser power at the output for 1,5Vpp are 204uW.

There's only one problem, in my case the focus potentiometer is all at the left, the signal is clean but I think it could be more clean. I think it's due the RLD-78MA diode is different than the original, and the tolerance is at the limit.

I hope do the experiment again with other diodes that I've purchase and are on way. I want to do the experiment with a KSS-151A too.
I don't have any KSS-190A, but the process must be equal like KSS-151A.

Some pictures. I know, I'm not a great photographer, and the workshop is mess but, what workshop isn't?

KSS-272A June 2020 - Google Photos

Regards
  Reply With Quote
Old 29th June 2020, 08:26 PM   #2
ManoloMos is offline ManoloMos  Spain
diyAudio Member
 
Join Date: Dec 2019
Location: Canary Islands
Hello. This is the second KSS-272A with new laser diode, changed successfully.
The RF output was a bit weak, and few years ago I had to adjust of position of the piece which contains the coils and the movil lens. I don't know why happened this kind of disajustment.
Well, like the other laser pickup, I removed the laser and clean the zone. I checked the laser and... ohh surprise! The output laser was right, 6-7mw.
Anyway I changed the laser diode of a Rohm RLD78-MYA. The former laser pickup was a Rohm RLD78-MA. I placed the diode, glue, and to wait.

Then, I placed the piece which contains the lens and coils in right form, because years ago I moved it like I said.
Then, I removed the photoarray glue, unstick the photodiode array and clean the zone, then air with pressure.

Then adjust, like always, a-b-c-d-e-f diode signals at the oscilloscope. This time the adjust point was more difficult, or it seemed to me. The DC focus offset was 400mv, the other pickup 700mv. Is this difference due to use different diodes? I don't know.
Then, when I got the right signal, lock with a screw, glue, and to waiting to dry.

One day afterward, today, I placed the diode. I had to adjust another time the place of the piece which contains the lens and the coils.
Focus Offset was not critical, but Tracking Offset or Tracking Balance potentiometer was crucial.

Laser power at the lens is 150uW and 1.6V RF output with a good cd.

The process is very summarized, but it get a lot of time and work. It is not easy, at least for me.

Some pics and some videos. Regards.

KSS-272A n2 Junio 2020 - Google Photos


YouTube

YouTube

Last edited by ManoloMos; 29th June 2020 at 08:30 PM. Reason: Oblivion
  Reply With Quote
Old 29th June 2020, 08:29 PM   #3
ManoloMos is offline ManoloMos  Spain
diyAudio Member
 
Join Date: Dec 2019
Location: Canary Islands
YouTube
  Reply With Quote
Old 30th June 2020, 05:05 PM   #4
Salar is offline Salar  Germany
diyAudio Member
 
Join Date: Feb 2006
Location: Germany
The eyepattern looks extremely well! Congratulations. You are the first one on diyaudio
-besides some guy who claimed to do this but never did show how- who proved that a diode swap can be done!
CD will now live forever!
  Reply With Quote
Old 30th June 2020, 05:45 PM   #5
ManoloMos is offline ManoloMos  Spain
diyAudio Member
 
Join Date: Dec 2019
Location: Canary Islands
Thank you. All this was possible thanks to the cd manual of the Pioneer P-D70 and a tutorial of Pioneer about this CD. In this manual appears how the cd laser are adjusted in factory, is not clear but was the clue.
As I said, in some pickups, like KSS-121A, BU-1, the laser can be replaced and adjusted moving slighly the diode.
In the KSS-272A and similar, it is not possible with this method.

I hope in the few weeks do it again with a KSS-271A , that is very similar to the KSS-272A, with different diodes.

I've bought the FFC/FPC cable of twenty contacts and 1.25mm separation for to try with the KSS-151A.
I hope it works, because it will mean that it will work with the KSS-190A, that is very rare. KSS-151A and KSS-190A are electrically and optically similar.

If you see, all this lasers are basically the same with the same optic block: KSS151A, KSS152A, KSS190A, KSS270A, KSS271A, KSS272A, KSS273A, KSS274A, KSS280A and KSS281A.

If you know how to do with one, you must know how to do with all.

I'd like to design a very precise power supply from -1V to +1V with the possibility of to add the low frequency signal for to excite the focus coils, the point where you find the right focus is very exact, as you see in the video with the oscilloscopes.

One last thing. The first KSS-272A has a little more of noise than the second, however, the first is able to read a CD-writed cd with a lot of scratches, the second reads this cd, but with difficult. Curious.



Regards
  Reply With Quote
Old 1st July 2020, 11:37 AM   #6
Salar is offline Salar  Germany
diyAudio Member
 
Join Date: Feb 2006
Location: Germany
This is very interesting as a very good book
about maintaining Compact Disk Players was written by Ken Klements,
a Pioneer and Sony technician. Nevertheless alignment was not covered much.
  Reply With Quote
Old 3rd July 2020, 07:09 AM   #7
percival007 is offline percival007  England
diyAudio Member
 
Join Date: Sep 2007
Quote:
Originally Posted by ManoloMos View Post
.....I removed the laser and clean the zone. I checked the laser and... ohh surprise! The output laser was right, 6-7mw.
It would have been interesting if you had reassembled the Laser Block at this point, I suspect it may have worked.

In my experience repairing CD Players, very few emitting Diodes have failed, it is usually the Receiving Diode array or more likely dust where it's ''not usually'' accessible.
You have proved that it is accessible and a good clean 'probably' cured your problem.

I slute your perseverence !!
  Reply With Quote
Old 3rd July 2020, 07:12 AM   #8
percival007 is offline percival007  England
diyAudio Member
 
Join Date: Sep 2007
Quote:
Originally Posted by Salar View Post
This is very interesting as a very good book
about maintaining Compact Disk Players was written by Ken Klements,
a Pioneer and Sony technician. Nevertheless alignment was not covered much.
Ken was (I don't know if he's still alive) a lovely fellow.
I attended many Training courses at Pioneer UK with Ken leading proceedings.

I would like a copy of his book but they have become very expensive and rare !!
  Reply With Quote
Old 3rd July 2020, 09:22 AM   #9
vt4c is offline vt4c
diyAudio Member
 
Join Date: Jan 2001
Location: Malaysia
ManoloMos,
Thank you for sharing your excellent work. I own a CDP with KSS-151A pick-up and are looking forward to your experiment again on changing the laser diode.
  Reply With Quote
Old 3rd July 2020, 09:48 AM   #10
Salar is offline Salar  Germany
diyAudio Member
 
Join Date: Feb 2006
Location: Germany
Tried to contact Ken Klements for my laser diode swap project.
There are some photos floating arond by laser repairers
What struck me was the fact that one can see the beam spots
superimposed over the photodiode-array spots.
Maybe this effect can be used for aligning?
See photos below:
Attached Images
File Type: jpg 000001.jpg (21.2 KB, 28 views)
File Type: jpg 000002.jpg (17.9 KB, 30 views)

Last edited by Salar; 3rd July 2020 at 09:53 AM.
 

Reply


KSS-272A Substitution of laser diodeHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Accuphase DP65/Sony - KSS 272A laser head markaudio Digital Source 17 18th February 2019 11:59 PM
quick question about improper PS diode substitution gary h Chip Amps 3 12th January 2012 07:19 PM
laser diode petronius Parts 0 7th March 2010 08:00 PM
WTB: Sony KSS 272A laser vadimgal Swap Meet 2 24th January 2010 01:58 PM
Ultrafast Diode bridge substitution fr0st Parts 10 16th February 2003 04:00 PM


New To Site? Need Help?

All times are GMT. The time now is 01:52 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki