Troubleshooting CD Players

[MaVeDo]

Necesitarás un osciloscopio con un ancho de banda mínimo de 60 MHz para solucionar este problema. Si no tienes uno, tendrás que buscar un técnico calificado.

Thank you very much.

In your experience, what do you think it could be? Laser, motors, circuits, transformer, rails?

 

[dr*audio]

Thank you very much.

In your experience, what do you think it could be? Laser, motors, circuits, transformer, rails?

You need to look at the rf waveform to see if it is low. If so, then check the voltage in the laser power supply. If that is good, the laser is bad.

 

[penmarker]

You need a scope to troubleshoot this properly, otherwise you are operating blind.

So the problem is somewhat intermittent?
1) Is there a micro switch that should register the closure of the tray? Does it work properly?
2) If you initially move sled away from the center of the disc, does it move back to the center when you insert a disc?

Thank you both for your help.
I found out the spindle height is too low. Perhaps after years of usage or maybe someone attempted to repair it some time ago accidentally pressed it in too deep.

It is running great now.

 

[dr*audio]

Thank you both for your help.
I found out the spindle height is too low. Perhaps after years of usage or maybe someone attempted to repair it some time ago accidentally pressed it in too deep.

It is running great now.

If you had a scope you could look at the focus output and see what the dc offset is. You set the table height so the offest is 0V. The disc motor shaft should have a dab of glue on it, before the table is pressed onto it to stake it in place. Use a glue like Elmer's white glue that won't make a hard bond to metal so it can be removed to replace the motor if needed.

 

[MaVeDo]

You need to look at the rf waveform to see if it is low. If so, then check the voltage in the laser power supply. If that is good, the laser is bad.

Thank you

I will send it to technical service.

I tried with another power supply before and the issue has not presented the error in 3 days.

I hope the warranty gives some explanation, if it is a bad laser, an electrical problem or I had it connected to a faulty power supply.

 

[dr*audio]

Thank you

I will send it to technical service.

I tried with another power supply before and the issue has not presented the error in 3 days.

I hope the warranty gives some explanation, if it is a bad laser, an electrical problem or I had it connected to a faulty power supply.

I meant the internal power supply for the laser. Not the external supply.

 

[penmarker]

If you had a scope you could look at the focus output and see what the dc offset is. You set the table height so the offest is 0V. The disc motor shaft should have a dab of glue on it, before the table is pressed onto it to stake it in place. Use a glue like Elmer's white glue that won't make a hard bond to metal so it can be removed to replace the motor if needed.

Thank you very much. To be honest I do have a scope but its a very hard to use USB scope (horizontal and vertical needs to be adjusted with the mouse and display is not nice - all sorts of annoying things) with bad background noise due to computer PSU. It does however correctly show me the Free Run Frequency Adjustment at 43.2MHz.

I found out after the CD player can run that I have the same issue as this person from 2020 which I think is explained by this section in a compatible service manual (CEC CD2100 with the same internals)

Not sure this is relevant, but the few rare times this cd-player is working (like right now, it can produce sound) is when it starts with an already-inserted cd and an already-closed tray. The other times I load a cd by opening and closing the tray, the sled blocks once it pokes the leaf switch. When working, if I deliberately stop it, open and close the tray without touching anything else, then it blocks as the sled touches the switch and that's it: game over aaargh! ...It is as if the CD player 'runs out of steam' if it goes through the whole loading process.
Maybe the sled's motor is wear and offers too much friction for reversing the sled's direction once the switch is touched... when monitoring the voltage rail of the sled's IC driver, I see they drop of 1V maybe 2 when the sled is moving, before going back to normal (16V or so). Could this be a sing of a leaky cap? it's speculative, but it feels like I am out of options.

It would work when I just turned it on but after playing one or two CDs it would not attempt to read the CD.
I noticed the lens moves back slightly after hitting the leaf switch and it would read. later on when the player had been turned on for a while the laser doesn't back away from the leaf switch and the lens doesn't try to focus.
When it does move away from the leaf switch the movement is deliberate because it slowly backs out and not like bouncing away from the stop limit.

I replicated it by stopping the lens from moving backwards to release the leaf switch and it would not focus. Once i nudged it away from the leaf switch laser turns on and it focuses.

So for some reason now after turning on for like 20-30 minutes the laser motor stops backing out away from the leaf switch causing it to not initiate focus.

 

[penmarker]

I think I’ve found the problem. The left is the original belt I took out from the deck. Right is one from my stash of belts.
Original looked like a normal rubber band so I replaced it with known good one.
But mine is thicker and stiffer. So when the laser moved to home position the belt rubbed against it. The friction makes it harder for it to back away, I imagine to crawl backwards gently it uses very low voltage and it couldn’t overcome the friction.

And since the belt is stiff I couldn’t use smaller diameter ones because it’ll be too tight and makes noise.
After several cycles of reading and tray eject, the belt would sit and settle loosely. This makes it rub against the laser more causing it to not move backwards.

With the original belt there’s plenty clearance between belt and laser.

But it’s still weird how the original belt looks like a normal rubber band.

 

[dr*audio]

View attachment 3370040

I think I’ve found the problem. The left is the original belt I took out from the deck. Right is one from my stash of belts.
Original looked like a normal rubber band so I replaced it with known good one.
But mine is thicker and stiffer. So when the laser moved to home position the belt rubbed against it. The friction makes it harder for it to back away, I imagine to crawl backwards gently it uses very low voltage and it couldn’t overcome the friction.

And since the belt is stiff I couldn’t use smaller diameter ones because it’ll be too tight and makes noise.
After several cycles of reading and tray eject, the belt would sit and settle loosely. This makes it rub against the laser more causing it to not move backwards.

With the original belt there’s plenty clearance between belt and laser.

But it’s still weird how the original belt looks like a normal rubber band.

It's not a rubber band, just a different color rubber. www.vintage-electronics.net has belts. Go to his website and measure the old one per his instructions and order one 10% smaller circumference.

 

[Ullar]

Holiday greetings to everyone!
Got my Technics SL-P1300 working after replacement of the PLL and Data Slice IC.
Initial state: Player starts up and focuses but does not read TOC.
Thanks for your help dr*audio.

 

[phil916]

hello Audiokarma and thanks dr*audio for this incredible thread and knowledge you share with community

i never had success troubleshooting CD players and it's not going better with my last try
so i'm asking for help please

it's a slot in CD player found in Rotel slot in RCD-12 | RCD-1520 | RCD-1570 | RCX-1500models
no success downloading a PDF service manual for these, so if someone has one or link to one thanks !!!!

problem was well known fail inserting or ejecting disk (belt or with more abuse pignon)
parts are unobtainium so i glued the cracked pignon, IPA cleaned belt and conical rolls for testing and it worked ...
though with unhappy pignons noise + some mechanical noises + TOC was displayed only after 2 to 3mn...
so i purchase a new complete CD bloc from brand autorized center.

I mounted the new one, desoldered anti-ESD blob ...
load and unload CD are now perfect, PINK floyd CD spin, laser pickup move looking for TOC, laser red light's on,
but TOC is never displayed, only "Loading"


after some search i found it use a CD DVD Sony ? bloc referenced KHM-313AAM but i found no datasheet or adjustment or test points information about it ...
I see there is CD and DVD independant laser power adjustment pots (so i suppose)
but i don't know who is who, and not sure where is the rf test point on this (red cercle ? )





i tested again with old CD bloc to confirm again ribbon cable (tired) is ok and TOC acquisition still WAY to long but after 3mn it plays

i understand these can be defective if received from aliexpress but from a brand autorized center i still doubt it
did i missed something ? how to test it please ?

thanks

 

[dr*audio]

hello Audiokarma and thanks dr*audio for this incredible thread and knowledge you share with community

i never had success troubleshooting CD players and it's not going better with my last try
so i'm asking for help please

it's a slot in CD player found in Rotel slot in RCD-12 | RCD-1520 | RCD-1570 | RCX-1500models
no success downloading a PDF service manual for these, so if someone has one or link to one thanks !!!!

problem was well known fail inserting or ejecting disk (belt or with more abuse pignon)
parts are unobtainium so i glued the cracked pignon, IPA cleaned belt and conical rolls for testing and it worked ...
though with unhappy pignons noise + some mechanical noises + TOC was displayed only after 2 to 3mn...
so i purchase a new complete CD bloc from brand autorized center.

I mounted the new one, desoldered anti-ESD blob ...
load and unload CD are now perfect, PINK floyd CD spin, laser pickup move looking for TOC, laser red light's on,
but TOC is never displayed, only "Loading"


after some search i found it use a CD DVD Sony ? bloc referenced KHM-313AAM but i found no datasheet or adjustment or test points information about it ...
I see there is CD and DVD independant laser power adjustment pots (so i suppose)
but i don't know who is who, and not sure where is the rf test point on this (red cercle ? )

View attachment 3382266View attachment 3382267

View attachment 3382272

i tested again with old CD bloc to confirm again ribbon cable (tired) is ok and TOC acquisition still WAY to long but after 3mn it plays

i understand these can be defective if received from aliexpress but from a brand autorized center i still doubt it
did i missed something ? how to test it please ?

thanks

Send the new assembly back, you got a defective one.

 

[phil916]

thanks this would be great if it was available quick solution but unfortunately not (i waited 3 month for this piece) and worse seller is telling me i probably made it faulty...
so seems i'm on my own

can you please elaborate on your conclusion ?
can i solve the issue on my side but it take time (i have) and knowledge (i can learn) ?
or there is nothing i can do myself with it ?

my initial problem to solve was slot-in mechanical problem, this is solved with the new CD bloc which mechanics work perfectly...
though his pickup is not reading TOC,
one step ahead two step back

plan A
i'm on my own to solve the new pickup not reading TOC problem... question is
can i test/repair it myself ?

as plan B solution i ordered from china supplier another new motors and pickup assembly (cost is low and seller seems to have okish feedback)


within waiting to receive it,
can you please help about what to test to understand and confirme the new pickup i have has a problem and maybe repair/tune it ?
as exemple i would like to control RF eye pattern but i'm not sure about where is the test point ?

thanks a lot

 

[dr*audio]

thanks this would be great if it was available quick solution but unfortunately not (i waited 3 month for this piece) and worse seller is telling me i probably made it faulty...
so seems i'm on my own

can you please elaborate on your conclusion ?
can i solve the issue on my side but it take time (i have) and knowledge (i can learn) ?
or there is nothing i can do myself with it ?

my initial problem to solve was slot-in mechanical problem, this is solved with the new CD bloc which mechanics work perfectly...
though his pickup is not reading TOC,
one step ahead two step back

plan A
i'm on my own to solve the new pickup not reading TOC problem... question is
can i test/repair it myself ?

as plan B solution i ordered from china supplier another new motors and pickup assembly (cost is low and seller seems to have okish feedback)
View attachment 3383133

within waiting to receive it,
can you please help about what to test to understand and confirme the new pickup i have has a problem and maybe repair/tune it ?
as exemple i would like to control RF eye pattern but i'm not sure about where is the test point ?

thanks a lot

I suggest you take the gears you need from the new mechanism and use them to fix the original.

 

[phil916]

thanks i'm surprised seems to me (CD systems ignorant!) so much more work than replacing with the laser bloc assembly i purchased

i discovered it's the same Sony laser bloc assembly that is used on SACD player NAD M5 C/AH, which service manual is available thoug i still don't fin,d info about pots and RF signals level

I made a video of problem
laser turn on about 35seconds from start ... which from what i read seems "normal" for these ROTEL, i don't know why so much time to go to TOC, though here it never find it

 

[dr*audio]

thanks i'm surprised seems to me (CD systems ignorant!) so much more work than replacing with the laser bloc assembly i purchased

i discovered it's the same Sony laser bloc assembly that is used on SACD player NAD M5 C/AH, which service manual is available thoug i still don't fin,d info about pots and RF signals level

I made a video of problem
laser turn on about 35seconds from start ... which from what i read seems "normal" for these ROTEL, i don't know why so much time to go to TOC, though here it never find it

The original mechanism had a good laser and played the CD but the gears were bad. That's why I told you to take the gears out of the new mech and put them in the original one. Did you do that?

 

[phil916]

i understand though i would have thinked it's way easier to take the whole original pickup assembly
and mount it to the new mechanical bloc instead of dismounting all inside to transfert to old bloc as transfering new gears and all parts from new bloc to old one seems an enormous and hasardous task (to me)
i'm sorry english is not native for me so i think i'm unclairly expressing myself here

what do you think about what you see in video please ?

 

[dr*audio]

i understand though i would have thinked it's way easier to take the whole original pickup assembly
and mount it to the new mechanical bloc instead of dismounting all inside to transfert to old bloc as transfering new gears and all parts from new bloc to old one seems an enormous and hasardous task (to me)
i'm sorry english is not native for me so i think i'm unclairly expressing myself here

what do you think about what you see in video please ?

It acts like the laser is bad.

 

[phreds_CD]

Hi - I have read about half of this thread and applied what I learned to a NAD5170 CD player that tends to skip forward or back about half-way through a CD. The CDs play fine on another player.

I lubed the top of the disk motor and the slide and rod with triflow and think there was some reduction in the skipping, but there is still some. Sometimes the skipping repeats at the same time point on a track (for a given CD), and other times the CD will play right on past the skipping point. Some variability.

The other symptom is a bit of a grinding noise when skipping from the first to the last track on a disk, or from the last to the first, causing maximum movement of the laser assembly.

I have looked for a replacement laser, but most have a vertical connector while this unit has a horizontal connector, as shown in the image. I'm hoping someone can identify a good replacement for this laser.

Also appreciate any other direction on this.

Thanks very much, and Happy New Year!

 

[phil916]

As you constated some skipping reduction with new grease
in case ... may i ask if you cleaned the rod and inside the bearing holes of pickup assembly with IPA on a swab stick before regreasing ?
seems maybe there is still hardened grease ?