Need some help/guidance on where to start with diagnosis on this CD changer. I've owned it since new (1990) and it was rarely used. This unit has maybe 40 hours of play time on it, most of the last 25-30 years it's been in storage (indoor, climate controlled). Recently pulled it out to play a few CDs and it's not working. It spins up the disc, changes speed, the laser will move from inside out, but never is able to read it and it gives up. Here is a short video of what it's doing:
I've searched around online and even found a few threads on this forum. I checked the main board and the original electrolytics look okay (I did not remove or test any of them). The lens is clean (IPA). The motor seems to be a bit noisy and vibrational--not sure if this is within tolerance--not sure how this would have failed just from sitting. I tried probing the marked RF point on the laser board with my scope, basically nothing there.
Another note, when I first opened it up, I saw it actually spin the CD backwards, and it was also dropping the disc while still spinning. Not sure if that means anything, but made me think the motor or a sensor may be faulty. Since trying it a few more times it's stopped doing all of that.
What is the general process for diagnosis on a CD player? It appears I'll need to get the factory service info to do anything, but should I chase the motor vibration first? Or address the lack of RF? Or are these machines old enough now that they should get recapped before doing any other diag?
Thanks for any advice,
Michael
I've searched around online and even found a few threads on this forum. I checked the main board and the original electrolytics look okay (I did not remove or test any of them). The lens is clean (IPA). The motor seems to be a bit noisy and vibrational--not sure if this is within tolerance--not sure how this would have failed just from sitting. I tried probing the marked RF point on the laser board with my scope, basically nothing there.
Another note, when I first opened it up, I saw it actually spin the CD backwards, and it was also dropping the disc while still spinning. Not sure if that means anything, but made me think the motor or a sensor may be faulty. Since trying it a few more times it's stopped doing all of that.
What is the general process for diagnosis on a CD player? It appears I'll need to get the factory service info to do anything, but should I chase the motor vibration first? Or address the lack of RF? Or are these machines old enough now that they should get recapped before doing any other diag?
Thanks for any advice,
Michael
Sorry it's been so long since I replied... I purchased the factory service info for this changer so I'm not working on this blindly, just received that a day ago.
To update, now that I am able to get it into test mode, the laser does indeed light up. I checked the voltage at the optical driver and they are spot on. The troubleshooting flowchart gets me as far as step 4:
1. Does the laser diode illuminate? Yes
2. Does the focus lense move vertically for search operation? Yes
3. Does the spindle motor start to rotate? Yes
4. Does the focus loop servo operate? [TBD]
5. Does the tracking loop servo operate? [TBD]
6. Does traverse servo operate correctly? Yes
So the question now, how do I check the focus loop and tracking loop? It is just by measurement of waveforms? Or is it an observation of the laser movement?
Thanks,
Michael
To update, now that I am able to get it into test mode, the laser does indeed light up. I checked the voltage at the optical driver and they are spot on. The troubleshooting flowchart gets me as far as step 4:
1. Does the laser diode illuminate? Yes
2. Does the focus lense move vertically for search operation? Yes
3. Does the spindle motor start to rotate? Yes
4. Does the focus loop servo operate? [TBD]
5. Does the tracking loop servo operate? [TBD]
6. Does traverse servo operate correctly? Yes
So the question now, how do I check the focus loop and tracking loop? It is just by measurement of waveforms? Or is it an observation of the laser movement?
Thanks,
Michael