Philips CD960 problems

[ClassA]

Hi, I got the problems with my CD960. When the power is turned on, the spin motor turns counterclockwise a while then stop and the laser head moved up and down several times with weak light. Does anyone know what is the problem with my CD960(cdm1)?

 

[zygibajt]

Have you tried to clean the lens? Sometimes after years of use they develop the fog that is easy to wipe out. If this is not it try to swap the CDM1 from another working player, it's not a lot of work since the bottom of the enclosure is removable.

 

[ClassA]

Thanks for the suggestion but this is not the case. Is there any hit from the servo board?

 

[LeoJar]

Check the power supply especially the power to servo.

 

[ClassA]

Hi,
How to check it? Is there any check point on the servo board?

 

[LeoJar]

download the service manual and here is the area you need to check : +12 and -12.

 

[ClassA]

Thanks! What will be the root cause if the power supply is abnormal?

 

[QSerraTico_Tico]

No clock signal

 

[ClassA]

Don't know why disc spins anticlockwise?

 

[LeoJar]

It is why to check the powersupply first. If one of the power supply (+12 or -12V) was failed, the motor will rotate in reverse direction (or no braking effect). And if the powersupply is good. You need to check the servo related circuit. First check the easiest parts first.

 

[ClassA]

Thanks. I have replaced all old caps and broken diodes on the power supply board but nothing changes. What is the most possible parts needs to be checked first on the servo board?

 

[lcsaszar]

As other also suggested, please measure the power supply voltages. You will need a service manual or at least the circuit diagram. Marantz used to have the good habit of packing the schematic diagram with their appliances, and Philips CD-960 is identical to Marantz CD94.
BTW how did you manage to break those diodes?

 

[ClassA]

The diode issue is visible. It was broken into two parts. I just replaced it with a new one.

 

[ColinA123]

There is a 960 on Uk E-bay.
Serviced Dec 2017.
Does this mean they tweaked the laser power to get it playing and are looking to move it quickly?
Or am I bitter and twisted?

 

[ClassA]

Can anyone tell me what the normal 1K VR setting(?ohm) is for CDM1?

 

[lcsaszar]

The 1k is the laser current setting. It does not need any adjustment. If absolutely necessary, follow the service manual:

Play the test disc
Measure voltage on R309
Adjust VR 3180 for 575 mV +/-75 mV on R309

If you don't have a test disc, better not to touch it.

 

[ClassA]

Do you know the typical resistance setting for the 1K VR?

 

[Mooly]

There is no typical setting, it depends solely on the optical output of the laser diode and the current needed to produce that level of intensity.

 

[ClassA]

What will the 1K VR resistance be for a new CDM1?

 

[Mooly]

You are really not understanding the issue here.

A new laser diode has a very wide tolerance on the current required to produce a given optical output and this means the correct current could be anywhere from say 45 to 65 milliamps as an example. That might be a range of 300 to 600 ohms on the preset.

It is not possible to give a typical figure simply because there isn't one.