I have been working on a non functional kenwood dp x9010 CD player (transport only).
I read a lot of threads on alternative pick-up heads to replace the original head or even replace the laser diode with a new Rohm diode.
At the moment i am not yet sure if the laser is dead.
1) When i close the sled without disc i can see the lens moving up and down and (from an oblique angle) i can see some red light in the lens
2) When i put in a disc it fairly quickly reads the TOC (well at least it displays the amount of tracks and the total playing time)
But when i press play there is a clicking sound due to a fast forward and backward movement of the head. So the head moves to it's maximum travel and back again. The clicking sound comes from the head hitting the buffers at the end of the travel. After this the unit displays the TOC again. After that the disc rotates at a slow speed and the unit shows track 01 with 0:00 playing time
What did i do thus far:
- Cleaned the lens
- Checked the voltages on the complete unit.
- PSU voltages are Ok.
- On the servo board not all the voltages are according to the voltages in the service manual. I found a lot of negative voltages where there should be positive and vice versa.
- Due to the voltages being off i pulled the transistors in the servo circuit and checked them all ( with a Atlas DCA75) and found no issues.
- I replaced the opamps in the servo circuit with the same types.
- I looked at the RF signal (EYE-pattern) in test mode. I am not a specialist on this but from what i can see on my (digital) scope it does not look Ok when compared to other EYE-patterns i found online. It looks blurry.
Could it be the laser after all or is there something else to look at?
regards
I read a lot of threads on alternative pick-up heads to replace the original head or even replace the laser diode with a new Rohm diode.
At the moment i am not yet sure if the laser is dead.
1) When i close the sled without disc i can see the lens moving up and down and (from an oblique angle) i can see some red light in the lens
2) When i put in a disc it fairly quickly reads the TOC (well at least it displays the amount of tracks and the total playing time)
But when i press play there is a clicking sound due to a fast forward and backward movement of the head. So the head moves to it's maximum travel and back again. The clicking sound comes from the head hitting the buffers at the end of the travel. After this the unit displays the TOC again. After that the disc rotates at a slow speed and the unit shows track 01 with 0:00 playing time
What did i do thus far:
- Cleaned the lens
- Checked the voltages on the complete unit.
- PSU voltages are Ok.
- On the servo board not all the voltages are according to the voltages in the service manual. I found a lot of negative voltages where there should be positive and vice versa.
- Due to the voltages being off i pulled the transistors in the servo circuit and checked them all ( with a Atlas DCA75) and found no issues.
- I replaced the opamps in the servo circuit with the same types.
- I looked at the RF signal (EYE-pattern) in test mode. I am not a specialist on this but from what i can see on my (digital) scope it does not look Ok when compared to other EYE-patterns i found online. It looks blurry.
Could it be the laser after all or is there something else to look at?
regards
The Service Manual can be found on Hi-Fi Engine........
HiFi Engine - Owners and Service Manuals
Check the Drive Transistors for the Sled Drive. I did one recently which was riddled with Dry Solder Joints and had one failed (Open Circuit) Transistor.
p.
HiFi Engine - Owners and Service Manuals
Check the Drive Transistors for the Sled Drive. I did one recently which was riddled with Dry Solder Joints and had one failed (Open Circuit) Transistor.
p.
Although this could be many things, a blurry RF signal can be a sign that no tracking correction is being applied to the pickup. In test mode the player may well operate under that condition. Its a long shot but worth investigating non the less.
Eye Patterns looked at on Digital 'scopes do not look as they do on an Analogue 'scope.
Unless it is a really expensive one with a high refresh rate (I think that is what is needed).
Otherwise it is just a SIne Wave almost with no 'Squares' visible to check for cleanliness.
Try looking at the Eye Pattern on an Analogue 'scope.
Happy New Year,
P.
Unless it is a really expensive one with a high refresh rate (I think that is what is needed).
Otherwise it is just a SIne Wave almost with no 'Squares' visible to check for cleanliness.
Try looking at the Eye Pattern on an Analogue 'scope.
Happy New Year,
P.
That is what I was afraid of. I just “ upgraded” from a Philips/fluke DSO scope to a new Rigol and sold the old scope 😡
I will have to see if i can borrow an analogue scope to verify the RF pattern.
In the meantime i ordered replacement transistors for the linear motors that drive the sled.
Happy new year to all
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