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Troubleshooting CD Players

death_82 said:
Hi and thank you for sharing you experiences. i have a sansui CDP , its based on sony, it had some tracking faults an some scratch in sound, so i decided to change the laser current, i took off the pickup that is kss150A, and turn the potentiometer from .7 k to 1.1 k ,but when i inserted the pickup and started the machine , i saw that there is no action from the spindle nor laser light. i checked the pickup position switch and it was OK, but there is no reverse move for pickup. can you tell me what to do? thank you.
Click to expand...

This is wrong on so many levels. To properly adjust the laser power you need to monitor the rf signal with an oscilloscope or use a laser power meter. Removing the pickup and adjusting it to some arbitrary setting is a recipe for disaster.
Please start your own thread asking for advice.
 
dr*audio said:
This is wrong on so many levels. To properly adjust the laser power you need to monitor the rf signal with an oscilloscope or use a laser power meter. Removing the pickup and adjusting it to some arbitrary setting is a recipe for disaster.
Please start your own thread asking for advice.
Click to expand...

Sorry, but that is not how to adjust the Laser power.

Firstly, the laser power does not need to be adjusted. If there is a reduction in laser power as sensed by the 4 quadrant pin diodes, that would indicate that the laser output has diminished OR that there has been some attenuation suffered along the light path. The attenuation can be caused by dirt/film on the prism(s), grating, 1/4 wave plate, lens, or the disc. Attenuation can also be caused by the reflectivity of the disc.

The LOP (Laser Output Power) is controlled by an APC (Automatic Power Control) loop. The light output is sensed by a monitor diode that lives in the same header assembly as the laser diode. A laser power meter is set on the lens, the laser turned on, then the laser current is increased until the correct amount of light output is "seen" at the lens. If the current required falls within the manufacturers spec, the laser and light path are deemed "Good" and a label with that laser's IOP (Current OutPut) put on the optical assy. This is all done in a clean room where no attenuating effects (dirt/film) have had a chance to attenuate the light following the light path.

You can measure the IOP and compare it to the label on the optical assy. You can usually sample the voltage across the typically 22 Ohm resistor (when the laser is on) to get the voltage and calculate the current. If the measured IOP is 10%, or more, higher than the label, the laser has degraded. If the IOP is correct, but the RF waveform (eye-pattern) is attenuated, that indicates light path attenuation (or possibly a 4 quadrant diode bias issue). This may also be caused by a marginally reflective disc.

There should really be no reason to adjust laser power. Increasing the current will make the laser degrade faster. If it's not working and you have nothing to lose, why not?
 
dr*audio said:
If the CD doesn't spin, the pickup could be bad or the disk motor, or disc motor drive could be bad. If the player does focus search and the disc doesn't spin and you hear a sizzling sound, the disk motor is bad.
Click to expand...

Thanks for this thread! Coincidentally, I picked up a 2nd Generation CDP yesterday for cheap. Yamaha CD-X1 like this one:

http://audio-heritage.jp/YAMAHA/player/cd-x1.html

This is the first time I've ever bought a vintage CDP that didn't work! I guess luck has been with me until now.

The unit powers up. The disk drawer opens and closes quite briskly. When the disc is inserted, there is a light from the bottom of the tray that shines for about 3 seconds and then goes out. No list of tracks displays, and the unit will not play.

I removed the top and observed that the tray opens and closes with no issues. There is a very faint humming noise that lasts for a second, then stops, then goes again for about a second, then nothing. The disk does not spin at all, at any time.

Not sure what the next step in trouble shooting is. I have a multimeter, but no oscilloscope. Can you offer any advice? Thanks!
 
Wigwam Jones said:
Thanks for this thread! Coincidentally, I picked up a 2nd Generation CDP yesterday for cheap. Yamaha CD-X1 like this one:

http://audio-heritage.jp/YAMAHA/player/cd-x1.html

This is the first time I've ever bought a vintage CDP that didn't work! I guess luck has been with me until now.

The unit powers up. The disk drawer opens and closes quite briskly. When the disc is inserted, there is a light from the bottom of the tray that shines for about 3 seconds and then goes out. No list of tracks displays, and the unit will not play.

I removed the top and observed that the tray opens and closes with no issues. There is a very faint humming noise that lasts for a second, then stops, then goes again for about a second, then nothing. The disk does not spin at all, at any time.

Not sure what the next step in trouble shooting is. I have a multimeter, but no oscilloscope. Can you offer any advice? Thanks!
Click to expand...

Hey, Wiggy!
Follow the troubleshooting steps. Observe the laser lens from the side when you load a Cd into the player. Does it go up and down? Follow the steps, it tells you exactly what to look for.
 
dr*audio said:
Hey, Wiggy!
Follow the troubleshooting steps. Observe the laser lens from the side when you load a Cd into the player. Does it go up and down? Follow the steps, it tells you exactly what to look for.
Click to expand...

I may have to take some photos. I am actually not sure where the laser is. I know that sounds weird, but I could not find it.
 
Jon_Logan said:
Sorry, but that is not how to adjust the Laser power.

Firstly, the laser power does not need to be adjusted. If there is a reduction in laser power as sensed by the 4 quadrant pin diodes, that would indicate that the laser output has diminished OR that there has been some attenuation suffered along the light path. The attenuation can be caused by dirt/film on the prism(s), grating, 1/4 wave plate, lens, or the disc. Attenuation can also be caused by the reflectivity of the disc.

The LOP (Laser Output Power) is controlled by an APC (Automatic Power Control) loop. The light output is sensed by a monitor diode that lives in the same header assembly as the laser diode. A laser power meter is set on the lens, the laser turned on, then the laser current is increased until the correct amount of light output is "seen" at the lens. If the current required falls within the manufacturers spec, the laser and light path are deemed "Good" and a label with that laser's IOP (Current OutPut) put on the optical assy. This is all done in a clean room where no attenuating effects (dirt/film) have had a chance to attenuate the light following the light path.

You can measure the IOP and compare it to the label on the optical assy. You can usually sample the voltage across the typically 22 Ohm resistor (when the laser is on) to get the voltage and calculate the current. If the measured IOP is 10%, or more, higher than the label, the laser has degraded. If the IOP is correct, but the RF waveform (eye-pattern) is attenuated, that indicates light path attenuation (or possibly a 4 quadrant diode bias issue). This may also be caused by a marginally reflective disc.

There should really be no reason to adjust laser power. Increasing the current will make the laser degrade faster. If it's not working and you have nothing to lose, why not?
Click to expand...

I am not going to argue with you, of course it is better to measure the current along with the laser power, but what do you gain by it? If the laser output is low and the current is high, the laser is on it's way out, so turning the power up a bit will buy you some more time on a non - available laser pickup. Who cares if it hastens it's demise (this is hard to prove anyway and I have squeezed a few months more out of a laser that would not read properly before I increased the laser power. The only caveat should be you need to clean the lens first, and then if the output doesn't come up, adjust the laser power, WHILE MEASURING either the RF output or laser output. A small turn of the power adjustment pot can make a large increase in the current and then you will quickly lose the laser.
 
Thank you All For answers , and the discussions,
It seems that i have killed that poor laser, but is there any probability that the laser driver had been damaged?
 
death_82 said:
Thank you All For answers , and the discussions,
It seems that i have killed that poor laser, but is there any probability that the laser driver had been damaged?
Click to expand...

Go through the troubleshooting procedure. If you put a CD in and look from the side, does the laser pickup lens go up and down. Start with that and go through the step by step instructions. It is possible you simply left a cable disconnected or connected a cable to the wrong connector. There are several checks the player does before it turns the laser on, detailed in the instructions. I repeat, follow the checkout procedure.
 
Hi, and thank you again , finally i fixed that, there was a mistake in placing the sockets. but i l have learned so good things.
 
death_82 said:
Hi, and thank you again , finally i fixed that, there was a mistake in placing the sockets. but i l have learned so good things.
Click to expand...

Glad you fixed it. Advice for everyone: Buy a Sharpie and mark connectors as you disconnect. If there isn't room for numbers and letters on the connector, put dots on it and matching dots on the board or the mating connector.
 
dr*audio said:
Hey, Wiggy!
Follow the troubleshooting steps. Observe the laser lens from the side when you load a Cd into the player. Does it go up and down? Follow the steps, it tells you exactly what to look for.
Click to expand...

Sorry it took me so long to get back to this thread. I finally pulled the top off my Yamaha CD-X1 and looked inside while trying to play a CD. Here's what it does.

1) Power on. No problem.
2) Disc drawer open. No problem.
3) Insert CD and close drawer. No problem.

After that, nothing. I listened very closely and I heard two clicking noises, then nothing. With the cover off, I could see the CD itself does not spin. I could not see the laser at all.

So, I carefully unscrewed the spring-loaded 'flippy thing' on top of the CD that drops down onto it when the CD is loaded. It came off and I could see the laser underneath. I hit the open and close a few times with no CD in the tray and it appears that the two clicks I am hearing are from the laser itself; once the CD drawer is closed, the lens 'pops up' like a prairie dog twice. Then, nothing.

I see no light from the laser at all. I tried putting a piece of paper over it and looking at the paper to see if I could see a laser light, but I do not. I don't know if the laser is in the visible spectrum or not, but I would guess it is, right?

So perhaps the laser is burnt out? In any case, after the two clicking noises from the laser popping up twice, nothing. The disc never spins, nothing else ever happens.

Any thoughts? I went through the trouble-shooting steps, but I guess I'm not reading them correctly, I'm not arriving at a definite stopping place.
 
The laser is red, it should light when the lens try to focus on the CD. Don't look at the laser directly, but looking from a side, like 45º is OK. You'll see the light, is a visible red light. If you don't see it, it's probably bad.

At post #1 you have all the focus process explained. Follow those directions.
 
elnaldo said:
The laser is red, it should light when the lens try to focus on the CD. Don't look at the laser directly, but looking from a side, like 45º is OK. You'll see the light, is a visible red light. If you don't see it, it's probably bad.

At post #1 you have all the focus process explained. Follow those directions.
Click to expand...

OK, so no light, I guess the laser is bad. As to following the directions, I already said that I read #1 and tried, but got lost. I don't understand where it is pointing me. Sorry, but reading it again and again won't change that, which is why I asked.
 
Wigwam Jones said:
OK, so no light, I guess the laser is bad. As to following the directions, I already said that I read #1 and tried, but got lost. I don't understand where it is pointing me. Sorry, but reading it again and again won't change that, which is why I asked.
Click to expand...

The laser lens going up and down means it is doing focus search. It means the loading operations are all ok and the mechanism can load a CD correctly, and the pickup is in the play position. So with a CD in place, if the disk motor doesn't at least try to spin, you have a bad laser. Boat anchor.
 
dr*audio said:
The laser lens going up and down means it is doing focus search. It means the loading operations are all ok and the mechanism can load a CD correctly, and the pickup is in the play position. So with a CD in place, if the disk motor doesn't at least try to spin, you have a bad laser. Boat anchor.
Click to expand...

OK, thanks very much. I take it the laser can't be replaced? Just checking.
 
I have a minor problem with a newly purchased 1988 vintage JVC CD player that is not covered by the first post in this thread. It is a XL-Z444BK single CD player with a Phillips "Optima 4" CD mechanism.

The problem is that when I open the tray to insert or remove a disc, 90% of the time, it only stays open about 1 or 2 seconds, just barely enough time to remove or insert the disc. Occasionally, it will stay open about 15 seconds, which I think is what it should normally do.

I'm guessing that the charging time of one of the capacitors in the "Servo Section" on the main board controls the timing? I suppose it's due for a capacitor change, anyways, at 25 years old.

Also, sometimes the tray does not open, probably the aging belt is slipping, per the original post. I'll be buying a belt for it soon, if I can fix the too-fast tray issue.

I don't have a lot of money in it, only cost $5 with a working original remote, it sounds great connected to my Pioneer SX-1050!

Anyone have a link to an owners manual or service manual scan?
 
Marty said:
I have a minor problem with a newly purchased 1988 vintage JVC CD player that is not covered by the first post in this thread. It is a XL-Z444BK single CD player with a Phillips "Optima 4" CD mechanism.

The problem is that when I open the tray to insert or remove a disc, 90% of the time, it only stays open about 1 or 2 seconds, just barely enough time to remove or insert the disc. Occasionally, it will stay open about 15 seconds, which I think is what it should normally do.

I'm guessing that the charging time of one of the capacitors in the "Servo Section" on the main board controls the timing? I suppose it's due for a capacitor change, anyways, at 25 years old.

Also, sometimes the tray does not open, probably the aging belt is slipping, per the original post. I'll be buying a belt for it soon, if I can fix the too-fast tray issue.

I don't have a lot of money in it, only cost $5 with a working original remote, it sounds great connected to my Pioneer SX-1050!

Anyone have a link to an owners manual or service manual scan?
Click to expand...

There will be an open / closed switch for the drawer, clean it with De-Oxit, Inject into any crack or opening in the switch and work it 30 times.
 
Thanks again Dr*Audio!​

Deoxiting the switch fixed the tray problem! There was also a very tiny micro switch that senses that the head is fully at the start position, I Deoxited it, too.

It definitely needs new belts. There are two, one drives the tray, the other drives the screw gear to move the laser. It started slipping after I reassembled it, maybe I got some oil on it, and the CD would load and it would count the tracks, but it wouldn't play. Once I re-read your posts, I traced it down to the head not moving, and saw the belt was not getting traction on the motor pulley. I tried cleaning the belts and pulleys with 91% isopropyl, no luck. I'm an auto mechanic, when an old car with an old noisy V belt comes in, to get it by until the parts comes in I use a little "Gasgacinch" gasket cement on the old belt to quiet it. I had some and after removing the belts, I applied it to them sparingly and let them dry. Put 'em back on and the unit works perfectly now! The tray now opens instantly, every time, where once in a while I would have to hit the button a few times.

I had enough new capacitors on hand to completely recap the unit. Listened to it for 4 hours last night, even reads badly scratched discs without a skip! Sounds awesome!:music:

Anybody know or recommend a good source for new JVC belts?
 
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