tests
Still trying the 5mz velleman - not much luck.
Player still spinning with intermittent no sound after playing for a short while.
I made an interesting discovery though, gently tapped the plastic housing around the laser and it started playing again! Still listening and waiting for the fault to surface again to check if the problem may be a laser alignment issue. Or am i totally off the mark??
Still trying the 5mz velleman - not much luck.
Player still spinning with intermittent no sound after playing for a short while.
I made an interesting discovery though, gently tapped the plastic housing around the laser and it started playing again! Still listening and waiting for the fault to surface again to check if the problem may be a laser alignment issue. Or am i totally off the mark??
Theres nothing alignment wise you can do to the CDM12 pickups. Problems are either mechanical such as sticking or faulty laser/optics. Looking at the RF tells a lot though.
It should look as good as this and be around 1.5 volts peak to peak,
NDP 4 Quality Assurance
Thats a real picture from a scope and its absolutely exactly how it would be on any player.
If you can tap it then it may be mechanical. Another test is solder a couple of fine wires across the small sled motor that drives the pickup and monitor the DC voltage in play. It should be minimal as the sled inches forward. If the voltage suddenly starts to rise then that indicates the sled has "stuck" and the voltage builds trying to overcome the friction. If it does overcome the friction the sled jerks forward and the voltage falls again.
It should look as good as this and be around 1.5 volts peak to peak,
NDP 4 Quality Assurance
Thats a real picture from a scope and its absolutely exactly how it would be on any player.
If you can tap it then it may be mechanical. Another test is solder a couple of fine wires across the small sled motor that drives the pickup and monitor the DC voltage in play. It should be minimal as the sled inches forward. If the voltage suddenly starts to rise then that indicates the sled has "stuck" and the voltage builds trying to overcome the friction. If it does overcome the friction the sled jerks forward and the voltage falls again.
lets see...... you move the lens assembly back and forth by pressing FWD / BCKWRD.... and everything is okay again for a while....
why don't you see what is preventing fine (precise) lens-assembly movement when the CD player is left in play for long times? the focus servo adjust the lens for a "while" (electronically - electromagnets), before the whole lens assembly needs to move "mechanically" forward a lil bit...
Boky
I connected wires as per your suggestion: and monitored the player visually and audio ie dvm and speakers and amp connected.
Start: @6.36pm voltage = 0.53/0.48
6.41 ' = 0.48
6.49 ' = 0.43 still playing to track 5 with audio
6.51 = 0.42
6.55 = 0.38 no audio track 5
Tried a second cd: voltages started at 0.51
0.52
0.38V audio stopped at track 5.
Start: @6.36pm voltage = 0.53/0.48
6.41 ' = 0.48
6.49 ' = 0.43 still playing to track 5 with audio
6.51 = 0.42
6.55 = 0.38 no audio track 5
Tried a second cd: voltages started at 0.51
0.52
0.38V audio stopped at track 5.
I have three Marantz players cd63 67se and cd63KI- have replaced lenses on all of them not. Also tried the swap but it seems that both the KI and cd67 lens don't seem to be work when swapped.
I have taken the entire mechanism out of the player, removed the ribbon cables and pcb and inspected with magnifying glass - cleaned and greased rails (very ightly) and gears - but could not see any visible obstruction or misalignment that could interfere with precise lense movement. While writing this response the player has stopped and started (on it's own) at least three times -voltage across motor has dropped to 0.35v
Those voltages sound OK. If the sled physically sticks the voltage goes up and up.
So back to square one. If you can't get the RF signal to look like it does in the link posted earlier (and for whatever reason that might be... scope ? I don't know) then its difficult to suggest anything else to check really. That signal is so very important to check and evaluate.
So back to square one. If you can't get the RF signal to look like it does in the link posted earlier (and for whatever reason that might be... scope ? I don't know) then its difficult to suggest anything else to check really. That signal is so very important to check and evaluate.
When the laser is "on track" the tracking error from the photodiode array is zero. As the lens moves outward (driven by the tracking coils that move the lens left and right) then this error signal gradually increases. When the error reaches a predetermined level the sled motor has enough voltage such that it rotates a fraction. The tracking coil voltage then comes back down again.
From the results of the voltage test and the fact the time counter keeps incrementing, I think the problem lies elsewhere.
Sorry guys - I took readings for voltages from both the cd drive motor and the laser tracking motor - had these mixed up in the initial posting.
I did notice that when the audio cuts out the trend was laser tracking voltages go up to 0.16v while cd player drive motor voltage drops to below 4v to 3.8v.
I did notice that when the audio cuts out the trend was laser tracking voltages go up to 0.16v while cd player drive motor voltage drops to below 4v to 3.8v.
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That could point to a sled problem. The only way to really clean these is to remove the gears and wash them and clean all the old grease out of the teeth with some card or paper. Same for the rack on the laser. The soft blue nylon gear can suffer with burrs on the inner teeth.
The best ground is the one used by whatever chip is used to process the RF signal (the one on the main PCB).
The white gears don't suffer from the burrs unless they have been damaged. But they can suffer debris in the teeth.
You have to pop that clip off the sled motor. Its just sprung in place. Access at the top via two slits in the chassis. The white gear pulls off. Look carefully at the top of the gear and you'll see two "clips" molded into the gear that locate in a groove in the metal shaft the gear fits on. It is just a push fit but may need a bit of persuasion to be eased out.
Before you pull the white gear off try turning it by hand. It should be free (although I wouldn't call it smooth) to turn with no obvious sticking points.
The laser istself can be left on its rail although its easy to remove and refit (if a bit fiddly) if needed.
You have to pop that clip off the sled motor. Its just sprung in place. Access at the top via two slits in the chassis. The white gear pulls off. Look carefully at the top of the gear and you'll see two "clips" molded into the gear that locate in a groove in the metal shaft the gear fits on. It is just a push fit but may need a bit of persuasion to be eased out.
Before you pull the white gear off try turning it by hand. It should be free (although I wouldn't call it smooth) to turn with no obvious sticking points.
The laser istself can be left on its rail although its easy to remove and refit (if a bit fiddly) if needed.
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