Troubleshooting CD Players

Hey Doc great post. Was wondering if you might be able to give some advice on a Adcom GCD-700. Everything starts up normally and the first few tracks play very nicely. It then develops some noise or static in the mid tracks and won't even recognize the later tracks. Usually it will move to the next disc and the process starts over again. Also it will disable the selection of the disc it has moved from. I took a quick peak at the tracking mech and everything looks clean. Just wanted to get your thoughts before I dig into it.
 
Bob01464 said:
Hey Doc great post. Was wondering if you might be able to give some advice on a Adcom GCD-700. Everything starts up normally and the first few tracks play very nicely. It then develops some noise or static in the mid tracks and won't even recognize the later tracks. Usually it will move to the next disc and the process starts over again. Also it will disable the selection of the disc it has moved from. I took a quick peak at the tracking mech and everything looks clean. Just wanted to get your thoughts before I dig into it.
Click to expand...
Sounds like the sled may be binding. Normally, playing a few tracks and then failing means the laser is going, but then it would not play the next disc. Sounds like the sled moves to a certain position and binds. Remove the gear that drives the sled so it can move freely, and move it back and forth by hand to check. Also look for debris in the gears or a cracked gear.
 
Hello Dr*audio, thanks for your input, later today I will give it a look but when I unplugged the tray mechanism along with the pick-up there only were three cables/connectors securing the connections with the mainboard unless there is some hidden below the whole mechanism, in fact it's strange the pick-up focusing correctly (it moves up and down to focus) and as such retrieving the disk informations but not moving from track to track.

Any input appreciated, thank you!!!
 
Hi Dr Audio I wonder if you might be able to help, I purchased a used Technics SL-P1200 on ebay as not working, the fault was the laser does not find the TOC on the disk and therefore doesn't spin the disc, although on occasions it spun a couple of revolutions I suspected the laser so I also purchased a used working Technics SLP 111 which uses the same laser assy. I tried the SLP111 out and it worked fine so I removed the laser assembly and replaced it in the 1200, I got very excited and powered it up, exactly the same problem disk tries to spin on occasions but never reads TOC. I have watched the laser without a disk in and it does try to focus by moving up and down and it also returns to the home position if I move the sled. I have tried adjusting the disk height with the adjuster on the motor and it sometimes seems like I am getting somewhere as the disk may spin a couple of revs stop and go backwards half a rev but no track numbers ever come up on the display and it never plays. I have sprayed the motor spindle with switch cleaner and it spins very freely. I have cleaned the laser lense with camera lens cleaning fluid also. I have also shorted out the switch for the door as this is also supposed to be a problem this also made no difference.
Any ideas would be much appreciated.
Cheers Neil
 
It sounds like the player may need the electronic adjustments performed. Do not attempt to do this without an oscilloscope, you will screw them up so badly that even an experienced tech may not be able to get it working.
 
Doc in order to carry out the adjustments with the Oscillioscope do i need the so called Technics setup cd or can one be made?, they seem to be like Rocking Horse shit!
Cheers.
 
landy95 said:
Doc in order to carry out the adjustments with the Oscillioscope do i need the so called Technics setup cd or can one be made?, they seem to be like Rocking Horse shit!
Cheers.
Click to expand...
You can use any commercial CD. You are going to look at the eye pattern of the rf signal, and the tracking and focus signals.
 
Okay, all laser settings now complete using an oscilloscope, i have had to spin the disk up to speed by hand as the motor seems to struggling to supply the initial torque to get it going, once i achieve a certain speed the motor takes over and brings it up to full speed, i assumed the motor was knackered but if i try to slow it down by hand it has plenty of power. Thinking of changing the caps on the motor spindle board, any suggesstions. I have connected it up to my amp and it sounds impressive, justt need to get it running automatically now.
I have also noticed when it is first turned on all the digits on the dilpay illuminate and yet after scanning the disk TOC the display of the numbers track numbers is messed up! strange?
 
landy95 said:
Okay, all laser settings now complete using an oscilloscope, i have had to spin the disk up to speed by hand as the motor seems to struggling to supply the initial torque to get it going, once i achieve a certain speed the motor takes over and brings it up to full speed, i assumed the motor was knackered but if i try to slow it down by hand it has plenty of power. Thinking of changing the caps on the motor spindle board, any suggesstions. I have connected it up to my amp and it sounds impressive, justt need to get it running automatically now.
I have also noticed when it is first turned on all the digits on the dilpay illuminate and yet after scanning the disk TOC the display of the numbers track numbers is messed up! strange?
Click to expand...
If the SLP1200 has a brushless DC motor for the spindle, the motor is not bad it is not getting proper drive to spin up. Even if it is a regular DC motor, since it has good torque once running the motor is probably ok. The display makes me think you have a power supply problem. Check the power supplies and check the 5V supply with a scope to see if there is ripple on it. Check them all with a scope for correct DC voltage and ripple. More than 10% ripple means the caps are bad.
 
HI Dr*Audio, The CD player in my wife's GMC Yukon has trouble playing CD's. I have owned a few GM vehicles with this very same Stereo/CD player and none of them have ever had any problems playing CD's, including CD-R's but this one is having trouble with all CD's.
I have read all of your instructions at the beginning of this thread so I'm ready to do some troubleshooting. Any other hints would be greatly appreciated.
Thank you, Bob
 
WE6C said:
HI Dr*Audio, The CD player in my wife's GMC Yukon has trouble playing CD's. I have owned a few GM vehicles with this very same Stereo/CD player and none of them have ever had any problems playing CD's, including CD-R's but this one is having trouble with all CD's.
I have read all of your instructions at the beginning of this thread so I'm ready to do some troubleshooting. Any other hints would be greatly appreciated.
Thank you, Bob
Click to expand...
Car CD players are nearly impossible to work on. As the preacher in Blazing Saddles said, "Son, you're on your own."
 
Between an extremely hostile working envirement re heat and plasticiser condensation, it's amazing they work at all for longer than a couple years.
 
dr*audio said:
Car CD players are nearly impossible to work on. As the preacher in Blazing Saddles said, "Son, you're on your own."
Click to expand...
Thank you very much for your response. Since it's not practical to work on the drive, can you recommend a brand/model of a replacement drive and possibly where to look for one?

BTW, Blazing Saddles is the best comedy ever made! Candygram for Mongo!

Thanks again! Bob
 
WE6C said:
Thank you very much for your response. Since it's not practical to work on the drive, can you recommend a brand/model of a replacement drive and possibly where to look for one?

BTW, Blazing Saddles is the best comedy ever made! Candygram for Mongo!

Thanks again! Bob
Click to expand...
I had good luck with JVC and Sony aftermarket units.
 
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