Hi Petr,
You're right: the voltage across that black (vertical, on the photo) resistor changes when turning the 1k pot. I've lowered it to 53mV as it was higher, but it didn't improve the CDM behaviour. On certain CDs, it's very hard to skip to the end of the disc. The CDM becomes very noisy and sometimes gives up with a scary protestation noise. I'll investigate more.
Henri
You're right: the voltage across that black (vertical, on the photo) resistor changes when turning the 1k pot. I've lowered it to 53mV as it was higher, but it didn't improve the CDM behaviour. On certain CDs, it's very hard to skip to the end of the disc. The CDM becomes very noisy and sometimes gives up with a scary protestation noise. I'll investigate more.
Henri
Hi Petr,
I've already tried to change the lytics and tantalum, but it didn't cure the problem. This problem started about six years ago. At that time, a cap was leaky on the main board near the SAA7020, which made the CD spin very fast. So it makes me think that a SMD component may have been damaged on the motor PCB itself.
Thank you for your help. I'm glad you helped me to adjust the laser voltage, that was set too high.
I'll give up a bit with it yet.
Henri
I've already tried to change the lytics and tantalum, but it didn't cure the problem. This problem started about six years ago. At that time, a cap was leaky on the main board near the SAA7020, which made the CD spin very fast. So it makes me think that a SMD component may have been damaged on the motor PCB itself.
Thank you for your help. I'm glad you helped me to adjust the laser voltage, that was set too high.
I'll give up a bit with it yet.
Henri
Attachments
I am rightnow busy to connect PCM56 with glue logic on a CDM2 based CD660. I never had reading problems with cdm2 in CD640, used it 19 years. I like cdm 2 for good sound and reasonable fast access to cd. Have a CDM1 in 304mk2 too, veeeeeery slooooow.
But the CD660 has problems. I adapted the cdm pcb right under the cdm2 and reduced so 30cm of HF cable to decoder pcb. All pcb's are re-arranged in new self build cabinet (get rid of 660's flimsy plastic one) First it worked, but later it has reading problems with some cd's and cdr's are very bad or not readed. Checked laser current, is 50 Mv along the red circled resistor in pict. in previous post. Changed lytics on cdm pcb allready.
What could be wrong here? Thanks.
But the CD660 has problems. I adapted the cdm pcb right under the cdm2 and reduced so 30cm of HF cable to decoder pcb. All pcb's are re-arranged in new self build cabinet (get rid of 660's flimsy plastic one) First it worked, but later it has reading problems with some cd's and cdr's are very bad or not readed. Checked laser current, is 50 Mv along the red circled resistor in pict. in previous post. Changed lytics on cdm pcb allready.
What could be wrong here? Thanks.
Hi,
On my CD150, a cap was leaky not far from the MCES pin of the SAA7020. The player couldn't read most CDs (just spinning very fast), but there were big exceptions. Some CDs played perfectly, even if the CDM often didn't like to skip straight from the beginning to the end. That was completely irrational... So, just have a look near the equivalent of the SAA7020, maybe is there a bad cap??
Henri
tubee said:
On my CD150, a cap was leaky not far from the MCES pin of the SAA7020. The player couldn't read most CDs (just spinning very fast), but there were big exceptions. Some CDs played perfectly, even if the CDM often didn't like to skip straight from the beginning to the end. That was completely irrational... So, just have a look near the equivalent of the SAA7020, maybe is there a bad cap??
Henri
lol this was not a quote: 
Yes, that's right, the CDM2 can be very reliable. I know a CD150MK2 that works perfectly with all its original components.
The CDM1 is a mighty mechanism but it becomes a nightmare when the spindle motor isn't perfectly adjusted. Mine "changes" with temperature variations! I can't use it anymore.
Yes, that's right, the CDM2 can be very reliable. I know a CD150MK2 that works perfectly with all its original components.
The CDM1 is a mighty mechanism but it becomes a nightmare when the spindle motor isn't perfectly adjusted. Mine "changes" with temperature variations! I can't use it anymore.
Off topic; am typing on a new OS, Kubuntu, have to get used to it.
Thanks for tips Henri, will look it over. Btw, SAA7020 i dont have, and SAA7220 neither. Clock goes direct in SAA7210 decoder.
The cdm1 has to be adjusted in height, and the axle could have too much friction, at least mine had. Screw some loose the two bolts which achors the bearing of spindle. Move it somewhat and tighten bolts. Do this until the axle turns freely. I did this with my CD304's CDM1 and solved some starting problems.
I cleaned the bearing also, the axle was little oxidated, scratched it off with fingernail. Lubricated it with some clock oil. But you have to dismantle the whole axle for that.
Try the moving first, see if it solves problems. CDM1 is very solid, if you're not in a hurry to listen a cd....
Thanks for tips Henri, will look it over. Btw, SAA7020 i dont have, and SAA7220 neither. Clock goes direct in SAA7210 decoder.
The cdm1 has to be adjusted in height, and the axle could have too much friction, at least mine had. Screw some loose the two bolts which achors the bearing of spindle. Move it somewhat and tighten bolts. Do this until the axle turns freely. I did this with my CD304's CDM1 and solved some starting problems.
I cleaned the bearing also, the axle was little oxidated, scratched it off with fingernail. Lubricated it with some clock oil. But you have to dismantle the whole axle for that.
Try the moving first, see if it solves problems. CDM1 is very solid, if you're not in a hurry to listen a cd....
Hi!
For your CD660, don't forget the blue axial Philips caps. They are extremely reliable but in my CD player one of them was faulty. That's extremely rare, a friend of mine who was a philips retailer told me they could keep their charateristics more than 30 years! That's true indeed, even if there are exceptions
Well it seems I'm the only guy who's not lucky with the CDM1! In the CD104 thread, I've mentioned what happens.
In the past, the problem could be cured by adjusting the motor height. It was not perfect though: I had the choice between a perfect playback on the whole CD (including on very long CDs) but with a starting problem(I had to help the motor) AND a perfect start but with difficulties to read the end of rather long CDs.
One day, I've removed the stator magnet ring so as to clean the motor height screw. From that day, it doesn't work anymore. I've spent hours adjusting the position of the stator magnet ring, and then the motor height. I sometimes obtain a good result, but the next day, I have to do it again!! This morning it couldn't play the CD over 50min!! I've checked the laser voltage, the PSU... Normally it should work! It makes me a bit mad, then I prefer not thinking of it too much. Not very healthy
I often come back to it after 2 or 3 weeks and think "this time is the good one". But each time, the same thing occures. Now the screws of the stator are damaged and no more reliable... If that machine wasn't a memory from my (mentionned below) friend I would get rid of it.
Henri
For your CD660, don't forget the blue axial Philips caps. They are extremely reliable but in my CD player one of them was faulty. That's extremely rare, a friend of mine who was a philips retailer told me they could keep their charateristics more than 30 years! That's true indeed, even if there are exceptions
Well it seems I'm the only guy who's not lucky with the CDM1! In the CD104 thread, I've mentioned what happens.
In the past, the problem could be cured by adjusting the motor height. It was not perfect though: I had the choice between a perfect playback on the whole CD (including on very long CDs) but with a starting problem(I had to help the motor) AND a perfect start but with difficulties to read the end of rather long CDs.
One day, I've removed the stator magnet ring so as to clean the motor height screw. From that day, it doesn't work anymore. I've spent hours adjusting the position of the stator magnet ring, and then the motor height. I sometimes obtain a good result, but the next day, I have to do it again!! This morning it couldn't play the CD over 50min!! I've checked the laser voltage, the PSU... Normally it should work! It makes me a bit mad, then I prefer not thinking of it too much. Not very healthy
I often come back to it after 2 or 3 weeks and think "this time is the good one". But each time, the same thing occures. Now the screws of the stator are damaged and no more reliable... If that machine wasn't a memory from my (mentionned below) friend I would get rid of it.
Henri
tubee said:
In that case Henri, the alignment of cd surface with laser arm movement is not correct, not parallel, and thus focus isnt right on end of cd compared to begin.
This can be adjusted with a clear cd. Make a clear cd of methacrylate 2mm thick, i did it that least. hole made with a large scissor, outer edge simply grinded on a table grinder.
Lay clear cd on the spindle, look in the reflection of a tubelight, check if reflection Tubelight is aligned with the reflection of laserlens. (But not sure if laserlens has a flat outerplane, if not you don't see a straight line in lens.) The human eye is very good with parellel lines (10 times better then normal sizes estimated) so its rather accurate.
Check it with different positions of laserarm, and with tubelight horizontal and vertical. Untighten first the screws of laserarm somewhat, adjust position of arm towards cd surface slightly, and when all is aligned tighten again. Nice job for a rainy sundaymorning.
A cdm service manual declares this also.
This can be adjusted with a clear cd. Make a clear cd of methacrylate 2mm thick, i did it that least. hole made with a large scissor, outer edge simply grinded on a table grinder.
Lay clear cd on the spindle, look in the reflection of a tubelight, check if reflection Tubelight is aligned with the reflection of laserlens. (But not sure if laserlens has a flat outerplane, if not you don't see a straight line in lens.) The human eye is very good with parellel lines (10 times better then normal sizes estimated) so its rather accurate.
Check it with different positions of laserarm, and with tubelight horizontal and vertical. Untighten first the screws of laserarm somewhat, adjust position of arm towards cd surface slightly, and when all is aligned tighten again. Nice job for a rainy sundaymorning.
A cdm service manual declares this also.
Hi,
thanks for the advice! You're probably right, but it looks quite scary! I'll think of it before trying.
Henri
thanks for the advice! You're probably right, but it looks quite scary! I'll think of it before trying.
Henri
tubee said:In that case Henri, the alignment of cd surface with laser arm movement is not correct, not parallel, and thus focus isnt right on end of cd compared to begin.
This can be adjusted with a clear cd. Make a clear cd of methacrylate 2mm thick, i did it that least. hole made with a large scissor, outer edge simply grinded on a table grinder.
Lay clear cd on the spindle, look in the reflection of a tubelight, check if reflection Tubelight is aligned with the reflection of laserlens. (But not sure if laserlens has a flat outerplane, if not you don't see a straight line in lens.) The human eye is very good with parellel lines (10 times better then normal sizes estimated) so its rather accurate.
Check it with different positions of laserarm, and with tubelight horizontal and vertical. Untighten first the screws of laserarm somewhat, adjust position of arm towards cd surface slightly, and when all is aligned tighten again. Nice job for a rainy sundaymorning.
A cdm service manual declares this also.
I am planning to swap pcb by pcb and at last CDM2 from my CD640 to the 660, and see when problem solves.
The real problem is: CDM2 makes a beeping noise on beginning of disk, some times interrupting and then it jumps/skips on sound too. When i go forward the beeping gets less obvious and tracking gets better. A focus problem would be the other way round.
I have CDM2/29 in my Grundig 9000. The can barely use track search, and the high tracks (>8) can not play in the selected mode. Use all the listed above recommendations and followed the repair manual to measure and adjust the laser power - helped, but did not resolved the problem. Any suggesttions?
Hi, I have a CDM 2/10 ( just the laser ! ) in perfect condition for sale if that is the problem.
BTW the motors of CDM 2/10 are way better than the standard CDM 4 motors but the laser does not last as long as the one in CDM 4. So I try to avoid CDM 2 cdplayers because of that. You have to draw a line somewhere.
I have to admit that replacement of the 33 uf cap ( and preferably all electrolytic caps ) cures the problems in a lot of cases.
BTW the motors of CDM 2/10 are way better than the standard CDM 4 motors but the laser does not last as long as the one in CDM 4. So I try to avoid CDM 2 cdplayers because of that. You have to draw a line somewhere.
I have to admit that replacement of the 33 uf cap ( and preferably all electrolytic caps ) cures the problems in a lot of cases.
CDM 2/10 Mech
Hello
Thank you for the offer Jean Paul but for the moment this mix and match seems to of worked as I said but for how long ? But after what you have informed me hopefully a little longer than the CDM 2 laser I have Rotel RCD 965BX bought from new with that CDM 4/19 mechanism and it has not skipped a beat. So it seems I have the best of both a CDM 2 brushless motor and CDM 4 laser. I must find a manual on how to fine tune/adjust and set up CDM lasers any leads would be appreciated.
Hello
Thank you for the offer Jean Paul but for the moment this mix and match seems to of worked as I said but for how long ? But after what you have informed me hopefully a little longer than the CDM 2 laser I have Rotel RCD 965BX bought from new with that CDM 4/19 mechanism and it has not skipped a beat. So it seems I have the best of both a CDM 2 brushless motor and CDM 4 laser. I must find a manual on how to fine tune/adjust and set up CDM lasers any leads would be appreciated.
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