Troubleshooting CD Players

[dr*audio]

I don't own as oscilloscope but I can get access to one and help using it. What is the process for adjusting the Technics SL-P2 with an oscilloscope?

The directions are in the service manual. Basically there is an rf waveform that you adjust the focus offset for the highest amplitude and most stable waveform, there is a tracking offset adjustment where you center the waveform, and focus gain ans tracking gain which usually do not need to be adjusted. There may be a sled offset that you adjust for 0V with a meter.

 

[rajkumar_]

Hi Dr Audio, I have Thorens TCD-2000 CD transport (laser Philips CD-PRO VAU1252 industrial) have problem as follow: when power on first time turntable motor turn reverse few second and stop no TOC reading, trying survival time after worm up at least an hour or more, can read all CD play very well (when worm up play very good) I was thinking laser weak and replaced with new laser again same problem with laser first time turn CD table reverse after hours motor can turn normal direction play very well meaning old laser still good, I was suspect replaced CD table motor with new one the problem not solved, before already check power supply board there was no dry solder joint all caps with in spec. Also I had check on CD-PRO drive board bottom of the laser pickup there are 2 SMD capacitor 47uf – 16v one in near motor connector other next to laser connector, when I measured reading 37uf instead of 47uf all other capacitor measured within value installed in PCB, I was installed normal capacitor 47uf -16v parallel to existing cap (not easy very narrow place and not sure properly soldered) because I’m worry remove old one from PCB, after solder cap in parallel the problem not solved. Also try to adjust laser pot (on laser unit) marked before turn and turn 1mm CW still no improvement and turn it CCW 1mm still the same and bring back to original position. Please help solve my problem, I still suspect that 2 SMD cap 47uf -16v should removed old one install new one and try again. Please noticed I have another legend CD player Marantz CD7 laser CD-pro VAU1254 industrial I had check laser drive PCB almost same, when I measured both capacitor same location 47uf-16v showing same value 33uf, but this player can read any CD play very well. Not yet try replace sled motor.

 

[rajkumar_]

Hi Dr Audio, I have Thorens TCD-2000 CD transport (laser Philips CD-PRO VAU1252 industrial) have problem as follow: when power on first time turntable motor turn reverse few second and stop no TOC reading, trying survival time after worm up at least an hour or more, can read all CD play very well (when worm up play very good) I was thinking laser weak and replaced with new laser again same problem with laser first time turn CD table reverse after hours motor can turn normal direction play very well meaning old laser still good, I was suspect replaced CD table motor with new one the problem not solved, before already check power supply board there was no dry solder joint all caps with in spec. Also I had check on CD-PRO drive board bottom of the laser pickup there are 2 SMD capacitor 47uf – 16v one in near motor connector other next to laser connector, when I measured reading 37uf instead of 47uf all other capacitor measured within value installed in PCB, I was installed normal capacitor 47uf -16v parallel to existing cap (not easy very narrow place and not sure properly soldered) because I’m worry remove old one from PCB, after solder cap in parallel the problem not solved. Also try to adjust laser pot (on laser unit) marked before turn and turn 1mm CW still no improvement and turn it CCW 1mm still the same and bring back to original position. Please help solve my problem, I still suspect that 2 SMD cap 47uf -16v should removed old one install new one and try again. Please noticed I have another legend CD player Marantz CD7 laser CD-pro VAU1254 industrial I had check laser drive PCB almost same, when I measured both capacitor same location 47uf-16v showing same value 33uf, but this player can read any CD play very well. Not yet try replacing sled motor.

 

[dr*audio]

It sounds to me like the Thorens player simply needs adjustment, one of the electronic adjustments is probably just out of operating range and when it warms up, it just comes into spec. I am not familiar with this player so you have to get the service manual and perform the adjustments.

 

[rajkumar_]

I do not have service manual, there are 2 adjustment spot and already adjusted marked original position turn both side and tested problem not solved. I still suspect all capacitor need to changed? When measured on-board all caps value within spec, I had noticed some cap sign of leaks.

 

[dr*audio]

Order the service manual. It's cheaper to pay for the manual than screw something up and have to pay someone to un-screw it up.

 

[SkyWilk]

Hello everyone. I am new to "old gear", but loving it already. Thank you so much Dr audio for your tips and advises. I followed your first page instructions, but i have no idea what is wrong with my device. Its a Yamaha CD-400 that came to my hands recently. When i put a CD in it, it spins for 3 seconds and stops, indicating no disc present. According to you, this means the laser is working, and detects that a CD is present (if i don't put a CD, the motor doesnt spin) and indeed i can see the laser light with my phone camera. I also see the laser moving forwards and backwards when a CD is inserted, so what else can be going wrong?

 

[dr*audio]

Hello everyone. I am new to "old gear", but loving it already. Thank you so much Dr audio for your tips and advises. I followed your first page instructions, but i have no idea what is wrong with my device. Its a Yamaha CD-400 that came to my hands recently. When i put a CD in it, it spins for 3 seconds and stops, indicating no disc present. According to you, this means the laser is working, and detects that a CD is present (if i don't put a CD, the motor doesnt spin) and indeed i can see the laser light with my phone camera. I also see the laser moving forwards and backwards when a CD is inserted, so what else can be going wrong?

Spinning means that the player was able to attain focus lock. The lack of a TOC being read, but the laser moves to home position and back means either the laser is too weak to read data or one of the adjustments is off. If you have an oscilloscope you can get the service manual and perform the adjustments. You can't adjust it without a scope.

 

[SkyWilk]

I see, thanks for your reply. Regarding the laser being weak, is it common? Any way to determine that this is indeed the true cause? Just so that if it is, i wouldn't lose my time with going the adjusting route..

 

[dr*audio]

I see, thanks for your reply. Regarding the laser being weak, is it common? Any way to determine that this is indeed the true cause? Just so that if it is, i wouldn't lose my time with going the adjusting route..

Unfortunately, if the player is 30 years old as this one is, the laser has reached it's life expectancy.

 

[redk9258]

Unfortunately, if the player is 30 years old as this one is, the laser has reached it's life expectancy.

Wouldn't that depend on the number of hours it has been used? Maybe some other component has drifted in value causing problems? Probably just wishful thinking.

 

[dr*audio]

Wouldn't that depend on the number of hours it has been used? Maybe some other component has drifted in value causing problems? Probably just wishful thinking.

By 30 years unless it has been in a closet for 20 years, it's probably got a lot of hours on it. My experience has been that the laser on an older player is usually on it's last legs. This is why I always tell people to not spend a lot on a used player, and to try to buy one that the laser is available.

 

[jjne]

Hi,

I have a Kenwood multi-CD player here, I know it's nothing special but I'd like to be able to give it a chance before it goes in the scrap. It's a nicely-made unit and always sounded good when it was working.

The model is DP-M6640, which uses the Sony KSS-210A. I haven't been able to find a service manual for it unfortunately. It doesn't seem to be able to find focus lock.

All mechanical functions of the player seem OK; I don't believe any of the file-cassette features are faulty. I believe the problem is with the electronics but I'm not sure where to go next.

When a disc is inserted, the player sends a brief pulse to the disc-spinning motor; I believe this is normal behaviour for some players to start the disc running slowly to aid the focus lock process. The pick-up will self-locate to the correct position in the TOC area of the disc, and the laser does light, and moves to attempt focussing. But the system does not lock focus, and the disc does not spin beyond the initial starter pulse.

This doesn't seem to be a problem with the laser however. I have swapped the pick-up with a known-working unit (from a single-disc Kenwood manufactured around the same time), and the pickup from the non-working player works in the working player, and the pickup from the working player fails in the non-working player in the same manner. I have also transplanted the entire KSM mechanism between the units with the same result -- the problem follows the player and not the mech. I even tried plugging the pickup into the broken unit while attached to the entire loader mechanism from the working one (the logic there being that the focusing distance between the laser and disc was known-good in this case) with again the same result.

So I am forced to conclude that the problem is with the electronics rather than anything mechanical. There are two pots on the player's PCB, TE bias and FE bias, which I tweaked slightly then returned to their previous positions, with no difference. My understanding however is that these are only needed once the player has found lock and is playing the disc itself.

My guess is that the output of the photo detector is not getting back to the intended destination on the PCB, and possibly there is a bad passive or transistor between the pickup and the IC, but I have no idea what the pinout is of the KSS-210A so I can't even begin to try to work out the path between the two.

Any assistance with this gratefully received, even if it's to provide a service manual appropriate to this unit to check the circuit on the board.

 

[dr*audio]

Hi,

I have a Kenwood multi-CD player here, I know it's nothing special but I'd like to be able to give it a chance before it goes in the scrap. It's a nicely-made unit and always sounded good when it was working.

The model is DP-M6640, which uses the Sony KSS-210A. I haven't been able to find a service manual for it unfortunately. It doesn't seem to be able to find focus lock.

All mechanical functions of the player seem OK; I don't believe any of the file-cassette features are faulty. I believe the problem is with the electronics but I'm not sure where to go next.

When a disc is inserted, the player sends a brief pulse to the disc-spinning motor; I believe this is normal behaviour for some players to start the disc running slowly to aid the focus lock process. The pick-up will self-locate to the correct position in the TOC area of the disc, and the laser does light, and moves to attempt focussing. But the system does not lock focus, and the disc does not spin beyond the initial starter pulse.

This doesn't seem to be a problem with the laser however. I have swapped the pick-up with a known-working unit (from a single-disc Kenwood manufactured around the same time), and the pickup from the non-working player works in the working player, and the pickup from the working player fails in the non-working player in the same manner. I have also transplanted the entire KSM mechanism between the units with the same result -- the problem follows the player and not the mech. I even tried plugging the pickup into the broken unit while attached to the entire loader mechanism from the working one (the logic there being that the focusing distance between the laser and disc was known-good in this case) with again the same result.

So I am forced to conclude that the problem is with the electronics rather than anything mechanical. There are two pots on the player's PCB, TE bias and FE bias, which I tweaked slightly then returned to their previous positions, with no difference. My understanding however is that these are only needed once the player has found lock and is playing the disc itself.

My guess is that the output of the photo detector is not getting back to the intended destination on the PCB, and possibly there is a bad passive or transistor between the pickup and the IC, but I have no idea what the pinout is of the KSS-210A so I can't even begin to try to work out the path between the two.

Any assistance with this gratefully received, even if it's to provide a service manual appropriate to this unit to check the circuit on the board.

The first thing to do here is swap out the connecting cables to the laser, with the working unit. Sometimes a wire goes open or there is a bad crimp on the connector. If that isn't it, it's either the rf amp IC or the servo IC, neither of which is likely to be available.

 

[jjne]

Thanks very much for the reply. I may have already done this by means of connecting the pickup within the single-CD working unit to the connectors on the non-working one, but there's a whole load of reasons why that might have failed, so I will try this next time I look at the unit. I have since had a look at the service manual for a Sony player with the same mech, and this should at least give me a fair idea of what I'm looking for in the event of examining the PCB (I have nothing to lose at this stage really!). The RF and servo ICs are available on AliExpress for very low cost, so assuming the same or similar parts (and I did note that the servo/RF ICs did appear to be Sony parts so it's possible) I might give it a go, and will report back if I make any progress. Just seems a shame to bin these old things when the newer replacements are such badly-made garbage in the main.

 

[dr*audio]

Most likely those IC's are counterfeit and will not work.

 

[jjne]

That's a pity, I had assumed that they were just used pulls to be honest.

 

[dr*audio]

The only supplier I trust for parts like that, or Japanese transistors is BD Enterprises. If they don't have it, the only thing you will find is counterfeit.

 

[Giovanni68]

Hello everybody, hey Dr Audio, very interesting thread and, guess, if am here it's because I have a problem, my old but trusty CDP-X505ES needed the tray belt being replaced and so I did, put it back, rearranged all the screws, top plate and back into the plug, of course I insert a disc being excited at having it back working and found out it doesn't recognize the disc, opened, cleaned the pick-up, the head moves freely up and down from rest to working position (apologize poor terminology but english is not my mother tongue) but what it doesn't do is to move back and forth to search the tracks on the loaded disc, I uploaded a short movie on youtube for you to see what am talking about, I dunno what might keep the pickup to move back and forth, seems like all the connections on the board are secured and working, if I pull it with a finger it moves freely and with no friction, the upper plate which keeps the disc in place also spins freely, any idea what might it be?

Thank you

Giovanni

Ok, found a little trick, there is a sort of a locking mechanism which keeps the pickup in place, looking at the player from above is on the right, it basically locks the pickup the nearest to the spinning mechanism, once the disc is loaded the OTC comes read but the disc keeps spinning and basically it seems the pickup stays there,

What can I check next?

Attached two pics of the pickup in place and displaced (locked and unlocked)

 

[dr*audio]

I think you may have left a cable unplugged. The linear motor for the sled isn't working at all. There is a coil that moves back and forth with the sled and there should be wires on it and a connector that should plug into the mother board.