I am repairing a Mark Levinson 39 (see my earlier post) and finally got the drawer working. However, after disk loading I still get the message "No Disk" and the CD is not spinning. My question: Is that info - disk loaded - supposed to come from the CDM12 unit? How/where is a loaded disk recognized?
I need to determine whether this is a Laser unit issue or a main board problem. If this is a CDM12 function: Any clue what the issue might be?
Thanks a lot!
I need to determine whether this is a Laser unit issue or a main board problem. If this is a CDM12 function: Any clue what the issue might be?
Thanks a lot!
Almost all service manuals will have a block diagram of basic functions, I suggest that you download a few and study them.
...
First and foremost, and to get you started, the processor needs to see two signals: the Loading switch OK and the Inner switch OK (for the latter, the Slide will need to be functioning as well; move the laser pickup to middle position and see if it moves towards the Inner switch)...
Good luck,
Nick
First and foremost, and to get you started, the processor needs to see two signals: the Loading switch OK and the Inner switch OK (for the latter, the Slide will need to be functioning as well; move the laser pickup to middle position and see if it moves towards the Inner switch)...
Good luck,
Nick
Perhaps a micro switch at the back of the tray not working? Press the switch to see if the 'no disc' message disappears. (Perhaps the tray doesn't slide all the way and doesn't activate the switch)
Thank you all for your response.
"Micro switch/loading switch":Unless I am grossly mistaken, the ML 39 does not have a loading switch but operates with two opto-elements to define drawer position. Both elements work, I checked that.
Regarding the Inner switch, I am going to test that today. Still my basic question remains: Does the CDM12 unit check for a disk present and then start to spin the disk? Or does the main control unit of the ML receives the "drawer closed" signal and then starts the CD drive motor? At this point I am not sure where I should focus on with my search: The CDM or the 39's main board.
"Micro switch/loading switch":Unless I am grossly mistaken, the ML 39 does not have a loading switch but operates with two opto-elements to define drawer position. Both elements work, I checked that.
Regarding the Inner switch, I am going to test that today. Still my basic question remains: Does the CDM12 unit check for a disk present and then start to spin the disk? Or does the main control unit of the ML receives the "drawer closed" signal and then starts the CD drive motor? At this point I am not sure where I should focus on with my search: The CDM or the 39's main board.
@Extreme_Boky: Can you get me some model names of CD-Player that use the CDM12? I will then try to find and download the schematics
CD loading mechanism is definitely different to Philips/ Marantz. I am sure you've tried to reset the unit with the instructions I found on the web:
1. Turn off the power at the back of the 39.
2. Press the drawer open button on the front of the 39 and keep it pressed while you turn on the power switch on the back of the 39.
3. With the drawer open button still pressed, watch the front display on the 39 change as the 39 runs through its cold start procedure. When you see the word "calibrate" in the display, remove your finger from the drawer open button and let the 39 cycle through whatever number of drawer openings and closings its software determines to be necessary until the drawer is deemed (by the software) to be calibrated.
1. Turn off the power at the back of the 39.
2. Press the drawer open button on the front of the 39 and keep it pressed while you turn on the power switch on the back of the 39.
3. With the drawer open button still pressed, watch the front display on the 39 change as the 39 runs through its cold start procedure. When you see the word "calibrate" in the display, remove your finger from the drawer open button and let the 39 cycle through whatever number of drawer openings and closings its software determines to be necessary until the drawer is deemed (by the software) to be calibrated.
Thank you both again for your continued support - I really appreciate! As you can tell I am not deep into the subject and I am not an expert on CD drives...
@freebee: I know the calibration procedure and I performed it without any issue. Drawer opens and closes twice during the process. however, at the end of the cycle the display reads "no disk"
@Nick: Just to clarify: My CD unit is not a "swing type" - it is CDM12 Ind, with a "linear" move of the lense. Upon power up, I can see the lense moving up and down, trying to focus, I can also see the lense unit moving from the inside out, or vice versa. It is just that the disk is not spinning.
Here is what happens when I load the disk with the following display reading sequence:
1. "No Disk"
2. I press "open" button for drawer: "Opening"
3. "Add disk"
4: I press drawer button again: "Closing"
5. "Reading"
6. "No disk"
So I assume from the above that the unit recognizes drawer opening and closing, recognizes the "closed" position and attempts to read the disk but can not "see" any disk.
So that is why I am trying to find out where the system gets the "disk available" signal from.
Thanks again
@freebee: I know the calibration procedure and I performed it without any issue. Drawer opens and closes twice during the process. however, at the end of the cycle the display reads "no disk"
@Nick: Just to clarify: My CD unit is not a "swing type" - it is CDM12 Ind, with a "linear" move of the lense. Upon power up, I can see the lense moving up and down, trying to focus, I can also see the lense unit moving from the inside out, or vice versa. It is just that the disk is not spinning.
Here is what happens when I load the disk with the following display reading sequence:
1. "No Disk"
2. I press "open" button for drawer: "Opening"
3. "Add disk"
4: I press drawer button again: "Closing"
5. "Reading"
6. "No disk"
So I assume from the above that the unit recognizes drawer opening and closing, recognizes the "closed" position and attempts to read the disk but can not "see" any disk.
So that is why I am trying to find out where the system gets the "disk available" signal from.
Thanks again
Hi Agosto,
from what you describe I think mechanically the player is working fine.
Just to make sure of the 'Home Base' switch, if you move the Laser away from its inner most position then watch what happens when you close the Tray.
Before the laser lights and tries to focus the laser should be driven into the inner most position (Home Base) and then it should light and attempt to focus.
If all this happens then I suspect you have a failed CDM-12.
I suspect it is a CDM12.4 that is fitted to your player. Simply this is the CDM12 with the first RF IC mounted to the laser block itself.
Have a look at this site (I have no affiliation to the site)
Service manual, eprom result list | Elektrotanya
and download the CDM12.1 and CDM12.4 Manuals. These will be invaluable.
You can then have a look at the output from the Laser when it is looking for a Disc. Do be aware these will be very small signals and difficult to 'scope but any movement of the trace could be used as an indication that there is something coming out of the Laser. Unfortunately this will be inconclusive but may just give a glimmer of something.
It is something resmebling the Focus S Curve signal you're looking for. Page 10 of the CDM12.1 Manual.
As I say this may prove inconclusive.
If you have room, you could try holding the disc a little closer to the lens. Sometimes with a defective Laser I have found this to just about get the laser to focus and you can hear the focus servos start to 'hiss'. Again, this is never a 100% test and may not work.
If you think you've nothing to lose then you could try to raise the output of the Laser Emitting Diode. This is done with a small Variable Resistor mounted on the Laser.
Usually this should never be adjusted, only at the factory when the unit is manufactured.
But as i say, if you have nothing to lose and tried all other possibilities then as a last resort it is worth a try.
Do it in very small increments making a note of exactly where you started from so you can return the pot to its original position. Try both ways as i cannot remember which is 'up' and 'down', sorry !
This may get you 'going'. If it does it does indicate the Laser is failed and this increase in Laser Power may only give you a few more weeks/months/(years hopefully!!).
I have had some sucess with Chinese copies available on eBay of the CDM12.1 but the percentage rate is lowering all the time.
I have had zero percent sucess rate with the CDM12.4 Chinese copies. I did work for an Authorised Philips Service Centre (independent) for some time but Philips never used the CDM Pro in any of their own units, they were all sold to OEM's and so I have limited experience on the CDM12.4. It may be that some electronic 'self adjustment' is performed by the electronics every time a disc is inserted and some sort of electronic based alignment is need for a new laser block. I do not know. I do know that this sort of self alignment was used by a lot of Japanese manufacturers in the later years of CD players.
There is a US or Canadian company who specialises in the repair of units using the CDM Pro Mechs (which often use the CDM12.4) and they have some for sale but they are expensive.
The company is
NEW Philips CD Pro 2
Again, I have no affiliation to them other than I have contacted them in the past and they have been very friendly and helpul.
I hope the above helps a little and keep us posted of your progress.
P
from what you describe I think mechanically the player is working fine.
Just to make sure of the 'Home Base' switch, if you move the Laser away from its inner most position then watch what happens when you close the Tray.
Before the laser lights and tries to focus the laser should be driven into the inner most position (Home Base) and then it should light and attempt to focus.
If all this happens then I suspect you have a failed CDM-12.
I suspect it is a CDM12.4 that is fitted to your player. Simply this is the CDM12 with the first RF IC mounted to the laser block itself.
Have a look at this site (I have no affiliation to the site)
Service manual, eprom result list | Elektrotanya
and download the CDM12.1 and CDM12.4 Manuals. These will be invaluable.
You can then have a look at the output from the Laser when it is looking for a Disc. Do be aware these will be very small signals and difficult to 'scope but any movement of the trace could be used as an indication that there is something coming out of the Laser. Unfortunately this will be inconclusive but may just give a glimmer of something.
It is something resmebling the Focus S Curve signal you're looking for. Page 10 of the CDM12.1 Manual.
As I say this may prove inconclusive.
If you have room, you could try holding the disc a little closer to the lens. Sometimes with a defective Laser I have found this to just about get the laser to focus and you can hear the focus servos start to 'hiss'. Again, this is never a 100% test and may not work.
If you think you've nothing to lose then you could try to raise the output of the Laser Emitting Diode. This is done with a small Variable Resistor mounted on the Laser.
Usually this should never be adjusted, only at the factory when the unit is manufactured.
But as i say, if you have nothing to lose and tried all other possibilities then as a last resort it is worth a try.
Do it in very small increments making a note of exactly where you started from so you can return the pot to its original position. Try both ways as i cannot remember which is 'up' and 'down', sorry !
This may get you 'going'. If it does it does indicate the Laser is failed and this increase in Laser Power may only give you a few more weeks/months/(years hopefully!!).
I have had some sucess with Chinese copies available on eBay of the CDM12.1 but the percentage rate is lowering all the time.
I have had zero percent sucess rate with the CDM12.4 Chinese copies. I did work for an Authorised Philips Service Centre (independent) for some time but Philips never used the CDM Pro in any of their own units, they were all sold to OEM's and so I have limited experience on the CDM12.4. It may be that some electronic 'self adjustment' is performed by the electronics every time a disc is inserted and some sort of electronic based alignment is need for a new laser block. I do not know. I do know that this sort of self alignment was used by a lot of Japanese manufacturers in the later years of CD players.
There is a US or Canadian company who specialises in the repair of units using the CDM Pro Mechs (which often use the CDM12.4) and they have some for sale but they are expensive.
The company is
NEW Philips CD Pro 2
Again, I have no affiliation to them other than I have contacted them in the past and they have been very friendly and helpul.
I hope the above helps a little and keep us posted of your progress.
P
Normally the CD spindle should turn and the lens move after the tray closes to read the Table of Content for 2-3 seconds. If nothing happens at all then I would check the cables from the PCB to CD mechanism. I have had to replace a bad cap once on the mechanism because it didn't want to focus properly and the CD kept skipping.
Have you checked the solder joints and caps?
Have you checked the solder joints and caps?
I wouldn't replace the CD mechanism yet. Spindle motor hardly ever fails is my experience and perhaps you can transplant a laser from a cheaper model. (Worked for me with CDM-4/16 to CDM-4/36)
Laser would still try to focus even if no longer good.
Laser would still try to focus even if no longer good.
Update: I found the problem. There was a bad connection between the D/A Board and the Main Board. So indeed there is a signal required from the D/A and/or Main Board to the CDM unit in order to let it spin the disc.
I am still testing all functions but so far it looks pretty good.
I am still testing all functions but so far it looks pretty good.
Ok, if the lens is moving up<->down but there's no spindle drive rotation:
1. the laser diode is not turning ON
2. the spindle motor is faulty (very unlikely), or the IC that drives the motor is faulty, or there's no clock signal (or.... maybe the power supply rail(s) are faulty)
3. The PAL chip (or whatever they decided to use and program with their custom logic code) might be faulty
I don't know anything about this CD player; the above are general "rules" and fault-finding suggestions.
You will need to have a good understanding of electronics to be able to check the above without schematics... also, you should be able to trace back the signals, from their endpoint destination (spindle motor, for example), backwards -> towards a suitable connector -> where you can measure the signals once the player is under a test / when you start the fault-finding process.
I don't know how else to help you, really... maybe ask for a circuit diagram..??
Edit: try to give a CD a "push" with your finger... I had few cases where the spindle motor commutator contacts were slightly shorted -> this was affecting a start-up torque capabilities... but once the spindle motor started to spin, the whole CD would play without an issue. The fix was a new motor.
1. the laser diode is not turning ON
2. the spindle motor is faulty (very unlikely), or the IC that drives the motor is faulty, or there's no clock signal (or.... maybe the power supply rail(s) are faulty)
3. The PAL chip (or whatever they decided to use and program with their custom logic code) might be faulty
I don't know anything about this CD player; the above are general "rules" and fault-finding suggestions.
You will need to have a good understanding of electronics to be able to check the above without schematics... also, you should be able to trace back the signals, from their endpoint destination (spindle motor, for example), backwards -> towards a suitable connector -> where you can measure the signals once the player is under a test / when you start the fault-finding process.
I don't know how else to help you, really... maybe ask for a circuit diagram..??
Edit: try to give a CD a "push" with your finger... I had few cases where the spindle motor commutator contacts were slightly shorted -> this was affecting a start-up torque capabilities... but once the spindle motor started to spin, the whole CD would play without an issue. The fix was a new motor.
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If it's a Philips based chip set then the D/A or the Digital Filter IC produces a clock which is fed back to the servo processing IC's which is where the Spindle Motor Drive originates. The signal used to be called (on older units where I have had this fault many times, apologies for not thinking of it !!) MC.
If this clock goes missing then the Spindle Motor doesn't spin or may spin backwards.
Glad you have it sorted.
P.
If this clock goes missing then the Spindle Motor doesn't spin or may spin backwards.
Glad you have it sorted.
P.
Thanks again for all your assistance! I finished testing the unit and I am happy to report that all is well!