Hi all, I’m new to this forum and I don’t know if I’m posting this in the right way.
However, I have a very annoying problem with a used Sony CDP-591 I bought a few weeks ago. The seller said that the only problem was the broken cart belt. Ok, i fixed it but the player cannot read discs, “no disc” all the times. So I tried a bit with the laser trimmers, looking on the internet to see what they corresponded to. First I turned up the power, then I adjusted the EF balance, now it could read but was very unstable with a lot of skipping.
So I gave up and bought a new KSS-240A laser unit. Today it arrived and I mounted it. Now it reads the discs perfectly but it skips a lot, both if I touch the player a little and if I listen at high volume. Here I made a few adjustments too but on the main board (I increased the balance gain slightly), it improved a little but still nothing significant. At this point I don't know what to do, I don't think it's a parameter setting error, and even if it was I don't have the equipment to adjust them properly. Does anyone have any ideas?
However, I have a very annoying problem with a used Sony CDP-591 I bought a few weeks ago. The seller said that the only problem was the broken cart belt. Ok, i fixed it but the player cannot read discs, “no disc” all the times. So I tried a bit with the laser trimmers, looking on the internet to see what they corresponded to. First I turned up the power, then I adjusted the EF balance, now it could read but was very unstable with a lot of skipping.
So I gave up and bought a new KSS-240A laser unit. Today it arrived and I mounted it. Now it reads the discs perfectly but it skips a lot, both if I touch the player a little and if I listen at high volume. Here I made a few adjustments too but on the main board (I increased the balance gain slightly), it improved a little but still nothing significant. At this point I don't know what to do, I don't think it's a parameter setting error, and even if it was I don't have the equipment to adjust them properly. Does anyone have any ideas?
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Have a read at this:
https://www.diyaudio.com/community/threads/sony-cdp790-and-kss240-restoration-project.226288/
Once you have altered the trimmers you will never get it back to optimum without a scope. Altering the laser power is the one thing never to do without test equipment. The better news is that if you can get a replacement KSS240 pickup then they are essentially plug and play.
https://www.diyaudio.com/community/threads/sony-cdp790-and-kss240-restoration-project.226288/
Once you have altered the trimmers you will never get it back to optimum without a scope. Altering the laser power is the one thing never to do without test equipment. The better news is that if you can get a replacement KSS240 pickup then they are essentially plug and play.
oh man, you’re right! The laser slides on that piece of plastic and if it is cracked it is normal that it does not slide well but now how can I repair it?
Yeah I read this before making this post but it wasn’t very helpful, then with this new laser unit I haven’t altered the power, I’ve only touched the ef balance pot and now is pratically at the factory value but it keeps skipping
I hadn't spotted that @huggygood had posted, it all looked like one post with all those images as I scrolled down 🙂 Well spotted.
If that is cracked then unless you can epoxy or whatever it back in place and get the pickup to slide smoothly then its game over.
If that is cracked then unless you can epoxy or whatever it back in place and get the pickup to slide smoothly then its game over.
Update: I took a closer look at the plastic piece where the laser runs and basically the only spot that could give the laser problems is in the middle, because the laser's travel does not reach the other broken spots of the plastic. It also always skips, even from the first track where the plastic track is still good. Can it be a suspension problem? The rubber seems quite hardened
yes, I even lubricated the plastic guide but nothing changed. I also tried to use the original laser unit and it works well but skips a lot like the replacement. I’m pretty sure it’s a mechanical problem but I’m very close to giving up and getting rid of it, online I can't even find the whole optical block 🙁
I understand, it may be that too, I have noticed that the disc does not spin linearly when being read. Anyway I found the replacement mechanism, it is from a cdp-297, but looking at the service manual it is the same model as the 591, a BU-5BD1. It includes the cart and the laser too! The seller could not tell me whether it was working or not, he was told it was working. Hopefully all goes well…🤞🏻
Can't tell off that. It perhaps looks fast but is that an artefact of the video. The disc should spin up initially at the same speed as you would see with it playing track #1
As the sled moves toward the outer edge of the disc (tracks nearer the end of the disc) then the speed slows considerably. If the disc plays and/or the time counter increments correctly then the disc speed will be correct.
One thing you you can check is that there should be no 'disc runout' at the edge. This means if you look at the disc edge on when spinning it should spin true and not be moving up and down. If you can see the lens in that position then the lens should not be moving up and down excessively. Any up/down movement of the lens means it is tracking a disc that is not running straight and level.
As the sled moves toward the outer edge of the disc (tracks nearer the end of the disc) then the speed slows considerably. If the disc plays and/or the time counter increments correctly then the disc speed will be correct.
One thing you you can check is that there should be no 'disc runout' at the edge. This means if you look at the disc edge on when spinning it should spin true and not be moving up and down. If you can see the lens in that position then the lens should not be moving up and down excessively. Any up/down movement of the lens means it is tracking a disc that is not running straight and level.
Thanks, the speed of the disc is good, the problem is that it goes up and down a bit too much, also in the video if you look closely it seems that the plate that blocks the disc spins a bit wrong. Fortunately I had a new replacement motor from another sony cd mechanic with the exact same model. I changed it and now it spins very well but it still skips. However now the laser recovers faster after a skip, then I noticed another thing, could it be the rubber that is used to grip the disc on the motor plate? Doesn’t seem to grip well
If you mean the eccentric wobble on the magnetic clamp then that is normal to varying degrees. The magnetic clamp is cone shaped and literally just drops onto the disc as the tray loads. Sometimes it will land more central than others.
The rubber on the platter should be clean so the disc sits flat and true. Once up to speed the friction needed to drive the disc is minimal. Problems with grip usually show more when doing track jumps from inner to outer edge of the disc where the motor speed has to change abruptly and also of course during initial start up to read the contents.
Its impossible to give reasons for the skipping without looking at the quality and amplitude of the signal from the pickup with a scope.
The rubber on the platter should be clean so the disc sits flat and true. Once up to speed the friction needed to drive the disc is minimal. Problems with grip usually show more when doing track jumps from inner to outer edge of the disc where the motor speed has to change abruptly and also of course during initial start up to read the contents.
Its impossible to give reasons for the skipping without looking at the quality and amplitude of the signal from the pickup with a scope.