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Sony CDP-270 with KSS-150A repair - adjusting the pots
Sony CDP-270 with KSS-150A repair - adjusting the pots
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Old 15th January 2018, 07:00 PM   #1
neptunes4you is offline neptunes4you  Hungary
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Sony CDP-270 with KSS-150A repair - adjusting the pots
Default Sony CDP-270 with KSS-150A repair - adjusting the pots

Hi Fellas!

Today i have bought a CDP-270 for $8, the guy basically wanted to get rid of it, because it just takes space. It obviously does not work properly. The laser emits a red light, it spins the CD, reads the TOC, but does not start to play immediately, and tracking also does not work as expected. It skips a lot, and sometimes misses out a few seconds.

I was just wondering if any of you here can help me with my restoration process. I have another CD player like this, and i love it, and i would like to resurrect this one for my girlfriend as a gift. I have an oscilloscope, so adjusting the pots should be no problem.

I have a complete service manual and all, but some help would be very good along the process. Tips and tricks, anything that can help me.
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Old 15th January 2018, 07:16 PM   #2
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
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Do not adjust any pots especially the laser power unless you fully understand how to set up the servo from scratch.
Fit a new laser assembly and play a good disk. Adjust the focus gain pot to the point just before it starts to squeal. That is all you can do.
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Old 15th January 2018, 07:24 PM   #3
neptunes4you is offline neptunes4you  Hungary
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Sony CDP-270 with KSS-150A repair - adjusting the pots
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Originally Posted by JonSnell Electronic View Post
Do not adjust any pots especially the laser power unless you fully understand how to set up the servo from scratch.
Fit a new laser assembly and play a good disk. Adjust the focus gain pot to the point just before it starts to squeal. That is all you can do.
Hi!

I don't want to completely mess it up, i just want to tweak what i can. So, you are saying that the only thing i can do at home with a scope is adjusting the focus gain pot?

I would like to totally repair this player if possible, if the laser is still good, i presume it only needs some tweaks. So, i obviously don't know how to set up the servo and how to properly adjust everything, but i would like to fix what i can with my oscilloscope. The only thing i don't want to touch is the pot on the KSS-150A, because as far as i know, it needs to be at an exact level, measured with a laser power meter.

Last edited by neptunes4you; 15th January 2018 at 07:27 PM.
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Old 15th January 2018, 07:38 PM   #4
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
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Being an ex Sony Service Centre engineer, now retired, I have seen many that have been twiddled and the only adjustment required, if at all, is the focus gain.
The service manual covers setting up and if the laser power is not touched, it is a simple job.
As I say, it is only the focus gain that ever needs touching and rule of thumb was adjust just before it squeals. That ensured good focus balance.
I used to get my service techs to photograph the pot settings before anything was adjusted. Just in case.
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Old 15th January 2018, 07:43 PM   #5
neptunes4you is offline neptunes4you  Hungary
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Sony CDP-270 with KSS-150A repair - adjusting the pots
Quote:
Originally Posted by JonSnell Electronic View Post
Being an ex Sony Service Centre engineer, now retired, I have seen many that have been twiddled and the only adjustment required, if at all, is the focus gain.
The service manual covers setting up and if the laser power is not touched, it is a simple job.
As I say, it is only the focus gain that ever needs touching and rule of thumb was adjust just before it squeals. That ensured good focus balance.
I used to get my service techs to photograph the pot settings before anything was adjusted. Just in case.
I want to mark them. Also, i suspect somebody has been inside the CD player before me, because the screws on the case are, well, screwed. I will adjust the F GAIN pot, and will come back with the results soon.
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Old 15th January 2018, 07:57 PM   #6
neptunes4you is offline neptunes4you  Hungary
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Sony CDP-270 with KSS-150A repair - adjusting the pots
Alright, i did that, nothing changed, except it got slower when i try to play the disc from the start.
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Old 15th January 2018, 11:00 PM   #7
neptunes4you is offline neptunes4you  Hungary
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Sony CDP-270 with KSS-150A repair - adjusting the pots
So, as i was trying to figure out what could be wrong, i have noticed that the pot on the laser is almost totally maxed out. On my other, fully working machine, it is on the center. This i think means that the laser was trimmed before by someone, and it is nearly dead. I have ordered a new laser unit from a UK seller, hoping it would not break down very fast. If it arrives i will try to replace it.
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Old 16th January 2018, 12:06 AM   #8
deadpool is offline deadpool  Australia
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probably the spindle motor is faulty
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Old 16th January 2018, 10:36 AM   #9
neptunes4you is offline neptunes4you  Hungary
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Sony CDP-270 with KSS-150A repair - adjusting the pots
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probably the spindle motor is faulty
How can i test it?
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Old 4th February 2018, 11:08 PM   #10
erin is offline erin  Australia
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Quote:
Originally Posted by neptunes4you View Post
How can i test it?
I had a sony KSS transport that would only read discs if the player was on an angle (lifting the front of the player), but if it was sitting flat on a surface it wouldnt play discs.

Turns out the bearing in the spindle motor was worn. It would chatter and vibrate when verticle to ground, but when placed sideways the spindle would rest on the bearing side wall and there was no chatter or vibration.

So because of the vibration, the disc was not reflecting light back to the pickup, the laser light was being scattered, so the disc couldnt be read.

When I removed the KSS transport and installed a new one the problem went away.

I tested the old spindle motor by spinning it by hand, it was easy to feel that the bearing had too much play.

Last edited by erin; 4th February 2018 at 11:16 PM.
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