When changing the pickup, how can the adjustments be made?
-50/50. Often work whithout adjust.
Is it necessary to have the test disk to run the service program? (Impossible to get)
-Absolutely NO. You can use any good disk.
Is it possible to adjust by moving only the EF bias and EF balance pots with an oscilloscope at the test points?
I Think no. You must go step by step all adjusting procedure.
-50/50. Often work whithout adjust.
Is it necessary to have the test disk to run the service program? (Impossible to get)
-Absolutely NO. You can use any good disk.
Is it possible to adjust by moving only the EF bias and EF balance pots with an oscilloscope at the test points?
I Think no. You must go step by step all adjusting procedure.
The tuning procedure with the digital servo that comes in the service manual is very confusing for me. If someone could help me ........
I have fitted the original kss-240 head from the Denon-615 player. It recognizes OCD very quickly and starts to reproduce sometimes until the end and sometimes it stops.
. Whenever I try to access a track the player stops, this can happen on any track.
What I can do?. I don't want to touch anything else without knowing.
I have fitted the original kss-240 head from the Denon-615 player. It recognizes OCD very quickly and starts to reproduce sometimes until the end and sometimes it stops.
. Whenever I try to access a track the player stops, this can happen on any track.
What I can do?. I don't want to touch anything else without knowing.
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The tracking servo loop not works correct.
E/F Balanse, tracking offset, tracking gain - must be ajusted.
I think the problem is not the laser pickup nor any bad adjustment. There is a clear fail or defect. Oscilloscope and service manual are your allieds.
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You always begin any fault-finding by checking all the supply rails are correct and clean. Check them at their destinations as well such as the motor drive amplifiers.
If the lens is focusing then look at the spindle drive signal from the servo and try and see if the servo is attempting to turn on the motor drive amplifier.
If the lens is focusing then look at the spindle drive signal from the servo and try and see if the servo is attempting to turn on the motor drive amplifier.
Mooly, Thank you very much, we learn a lot with you and you are very kind
When I can I will check the supply rails and post it.
We discarded the mechanical parts because it has been tested with two equal tables with the same results. The worst thing is that IC 101 or IC102 is damaged.
When I can I will check the supply rails and post it.
We discarded the mechanical parts because it has been tested with two equal tables with the same results. The worst thing is that IC 101 or IC102 is damaged.
When a CD player abruptly stops initializing discs I check these items first:
The small brush-type DC motors frequently used in CD players tend to develop dead spots where the motor won’t begin to rotate at the low voltages provided by the servo circuits. With the motor disconnected from the PC board I apply 0-6V from a variable power supply. When I test sled motors I remove one or more of the drive gears so that the sled won’t hit its end stops. I want the sled motor to be able to “free run.”
I measure the current flowing into the motor. A good motor should begin to rotate slowly with <1V DC applied. Then as the voltage is raised, it should speed up to 1000-2500RPM with 6V applied and the motor current should be <50mA. In fact most new motors consume only 25-30mA at 6V. Test the motor with both plus and minus DC polarity. Sometimes a faulty motor will “stick” for one direction of rotation but work better when rotating in the opposite direction. The motor current at 6V should be about the same for both directions of rotation. +/-20%.
These motors are readily available and cheap. I replace them whenever I suspect a problem with the old motor.
When replacing a spindle motor one must be careful to position the disc platter at precisely the same height as the old motor. Within +/-0.5mm is desirable. Measure carefully before removing the disc platter from the old motor. I use a vernier calipers for this. For some CD players the shaft length of the new motor must be exactly the same as the old motor. Otherwise the disc clamper won’t work properly. A longer shaft can be shortened by cutting with a Dremel tool abrasive cut-off wheel. The shaft end should be smoothed/filed to have the same profile as the old motor.
The detector switches for sled “home” position can often be disassembled and the contacts gently cleaned to remove oxidation. A piece of card paper soaked in contact cleaner can be pulled between the switch contacts. After cleaning the contact closed resistance should be <1 ohm.
-EB
- Spindle motor
- Sled drive motor
- Detector switch for “home” position of sled.
The small brush-type DC motors frequently used in CD players tend to develop dead spots where the motor won’t begin to rotate at the low voltages provided by the servo circuits. With the motor disconnected from the PC board I apply 0-6V from a variable power supply. When I test sled motors I remove one or more of the drive gears so that the sled won’t hit its end stops. I want the sled motor to be able to “free run.”
I measure the current flowing into the motor. A good motor should begin to rotate slowly with <1V DC applied. Then as the voltage is raised, it should speed up to 1000-2500RPM with 6V applied and the motor current should be <50mA. In fact most new motors consume only 25-30mA at 6V. Test the motor with both plus and minus DC polarity. Sometimes a faulty motor will “stick” for one direction of rotation but work better when rotating in the opposite direction. The motor current at 6V should be about the same for both directions of rotation. +/-20%.
These motors are readily available and cheap. I replace them whenever I suspect a problem with the old motor.
When replacing a spindle motor one must be careful to position the disc platter at precisely the same height as the old motor. Within +/-0.5mm is desirable. Measure carefully before removing the disc platter from the old motor. I use a vernier calipers for this. For some CD players the shaft length of the new motor must be exactly the same as the old motor. Otherwise the disc clamper won’t work properly. A longer shaft can be shortened by cutting with a Dremel tool abrasive cut-off wheel. The shaft end should be smoothed/filed to have the same profile as the old motor.
The detector switches for sled “home” position can often be disassembled and the contacts gently cleaned to remove oxidation. A piece of card paper soaked in contact cleaner can be pulled between the switch contacts. After cleaning the contact closed resistance should be <1 ohm.
-EB