Technics SL-P1300 CD Player Spin is Weak and Erratic

[VintageStyle]

About a year ago, my Technics SL-P1300 would occasionally make a scraping noise spinning up a disk or when it was running. I never gave it much thought, because it didn't occur often. Over the last few months, the frequency of the scraping noise increased. Additionally, the CD would have trouble spinning up to speed and would often falter and quit. Eventually, it wouldn't spin at all. I do not have a service manual so I'm flying blind (Hifi engine is the only source that I know. My membership expired and they're not accepting members at the moment), but I followed the advice in one of the threads and replaced the two surface mounted caps on the motor control board. This seems to have helped, but the disk will only spin if remove the disk clamp. It might spin for five or ten seconds at which point I will hear the scraping noise and the CD will stop. There is not a mark on the CD. If I let the disk run freely with out the clamp and slowly lower the clamp until it just engages the CD, the CD will immediately stop. This player uses a magnet rotor disk and three servo coils on the control board, so it is not your typical DC motor. If it were, I would say that the motor behaves as if it has no torque. There is every indication the Laser is working properly otherise I would never get it to spin for ten seconds, but I don't have the foggiest idea of what is causing the scraping sound or why the motor seems so weak. Any thoughts or ideas on what to look at next would be greatly appreciated.

 

[Sansuiman]

The lower half of the disc rest (attached to the spindle motor) is notorious for getting rusty on these. It needs to be clean and smooth for proper operation. It could also be that the disc spindle platter is sitting too low, and causing the disc to rub on the lower portion of the tray (recess on the 1200 and 1300) or on the lid, if sitting too high.

 

[VintageStyle]

The lower half of the disc rest (attached to the spindle motor) is notorious for getting rusty on these. It needs to be clean and smooth for proper operation. It could also be that the disc spindle platter is sitting too low, and causing the disc to rub on the lower portion of the tray (recess on the 1200 and 1300) or on the lid, if sitting too high.

Thanks for the suggestion. I checked the spindle and there was no rust present and it rotates freely. I share your assessment that the disk height is too low, but until I can get rotation, I'll wait to calibrate the height. I have out of spec voltages (according to a youtube video of the unit repair) on the two IC's that I believe are associated with the motor control, but without a schematic it's difficult to do any kind of intelligent analysis.

 

[Sansuiman]

Ok. Do be aware that the 1200 and 1300 also have a PLL circuit on a SIP circuit module (epoxy encapsulated mini circuit bard) that is a known point of failure. This doesn't sound like the issue you are having, but is a problem of increasing frequency on these players.

It is a bespoke Matsushita manufactured part, and no replacement is currently available for it. Vintage Audio Laser recently did a write-up on this, and he made his own replacement module. He didn't publish the design specs, not offer the sale of modules to others, so without contacting him, I don't know if his solution will be available in any form.

 

[VintageStyle]

I obtained a manual from servicemanuals.net (great copy btw, sharp and clear with color on the schematics). That helped me identify some voltages that didn't look quite right so I got out my ESR tester and found more than a few leaky electrolytics. Decided to replace them all (both polar and non-polar) and was hopeful that would solve my problem. My voltages now look good, but it offered no improvement of the spindle motor performance. It will still start and play for 5-10 seconds if I spin it by hand, but it will not self-start or continue to play. Trying to work on checking waveforms, but it's difficult to tell which one's are at rest and which one's are for "play." Open to any suggestions.

 

[cheep607]

I obtained a manual from servicemanuals.net (great copy btw, sharp and clear with color on the schematics). That helped me identify some voltages that didn't look quite right so I got out my ESR tester and found more than a few leaky electrolytics. Decided to replace them all (both polar and non-polar) and was hopeful that would solve my problem. My voltages now look good, but it offered no improvement of the spindle motor performance. It will still start and play for 5-10 seconds if I spin it by hand, but it will not self-start or continue to play. Trying to work on checking waveforms, but it's difficult to tell which one's are at rest and which one's are for "play." Open to any suggestions.

Could you please share the service manual?