I got some more information from my fiend who was servising those CDM's for a quite long time.
He told me to make the adjustment after the player is warmed up,let's say playing on repeat for 2-3 hours.
He also told me that it would be the best to use some special service CD disk that has a special tracks for those adjustments.
Sony and Philips have these kinds of CD's.
The reason is many parameters differ from CD to CD and even a brand new ,original CD may not be the best for precise adjustment.
Bartek
He told me to make the adjustment after the player is warmed up,let's say playing on repeat for 2-3 hours.
He also told me that it would be the best to use some special service CD disk that has a special tracks for those adjustments.
Sony and Philips have these kinds of CD's.
The reason is many parameters differ from CD to CD and even a brand new ,original CD may not be the best for precise adjustment.
Bartek
Do you think that i'm going to make a mistake if I use one of my cd, one that seems not to have a good TOC reading, to make the correct adjustement?
when you speak of differencies about various CD, do you mean some mV..?
thanks
Bye 🙂
when you speak of differencies about various CD, do you mean some mV..?
thanks
Bye 🙂
And what about the other adjustement?
the 50mV have to be stable in my opinion... I think that is not correlated to the cd used... it's probably a power regulation of the laser power that adjust the current into it... i'm thinking correct or not?
First of destroy my precious cdm
i have to know a little bit more...
Bye and thanks to you 😉
the 50mV have to be stable in my opinion... I think that is not correlated to the cd used... it's probably a power regulation of the laser power that adjust the current into it... i'm thinking correct or not?
First of destroy my precious cdm

Bye and thanks to you 😉
reading another post here i've found this... it's about a cdm2 but contains some interesting notice... http://www.beomuse.com/laser.html
I think that is not correct because watching better the schematic d1 and d2 are receivers...it's probably a power regulation...
Anyone has a complete schematic of a Cdm to share?
50mV is more stable.It doesn't change from CD to CD but it changes slightly from thr beginning of CD to the end.
Bartek
Bartek
What is interesting in the link above?
Exchanging electrolitics caps?
Sure it's a must.What would you expect from 15 years old el. caps?
Bartek
Exchanging electrolitics caps?
Sure it's a must.What would you expect from 15 years old el. caps?
Bartek
for me is interesting because i'm not experienced of laser units... i tweak audio equipment only for hobby, normally i work on micros, industial electronics and related controls to realize cards for others... audio for me is only a hobby... so in some arguments i'm very ignorant... 🙄
So now i know that is better to change also all the elecrolitic caps in the laser unit 🙂 , next week i'll dismount all and check the el. caps... that probably have to be low ESR...
thanks Bartek
Bye
PS for Fin..
Thanks for the info
So now i know that is better to change also all the elecrolitic caps in the laser unit 🙂 , next week i'll dismount all and check the el. caps... that probably have to be low ESR...
thanks Bartek
Bye
PS for Fin..
at the moment they replied me that they hasn't any cdm4/19... also they are looking for this units...CDM4/19 is available from Lubor at about 50 Euro IIRC.
Thanks for the info
Guys this thread is very useful for me and my Marantz CD-65DX with CDM4,but will be great if anyone can help me : what is this part : 3829 ,because I can find 3828 ,but in my player I can find may be and 3829 with more info.Thanks!

DoctorWho70 said:at the moment they replied me that they hasn't any cdm4/19... also they are looking for this units...
FYI I have several new CDM4 for sale.
Price please? I have several players with CDM4/36 , they work , for now.jean-paul said:
FYI I have several new CDM4 for sale.
I adjust laser current , by listening. I put orginal disc , turn trimer way down , and slowly rise the current until TOC is readed , then push play button and listening to music while turning current down. On some ponit the distorsion apears , then I slowly rise current up.
I do the same on bad copyed discs.
The laser is allways on when player is playing , but when you change laser current, signal strenght that comes out of photo diode is changed. But there is a low limit that decoder electronics need.
All cd´s don´t have the same reflection power.
I do the same on bad copyed discs.
The laser is allways on when player is playing , but when you change laser current, signal strenght that comes out of photo diode is changed. But there is a low limit that decoder electronics need.
All cd´s don´t have the same reflection power.
Gasho I can`t adjust the laser by listening,because my player can`t read any CD two days now.Will be great if anyone can give me approximately any value in Ohms for this two trimers when his player play good. When I can adjust with listening my player while he can read any CD.Thanks!

My laser is OK.I want only setting-up,but I can`t- accidentally I am to blame for this that he can`t read any CD.
I want setting-up the laser -the player is Marantz CD-65DX with CDM4- but I can`t find this read points for the voltage on my player. I can setup the laser by listening like you,but I want only your value of this two trimers(22K,4K7) ,because now my player can`t read any CD ,and nobody for the moment can`t help me with any picture of the CDM4 with the voltage-read points or any other instructions. And YES ,I `am sure that my laser is OK
Thanks!
I want setting-up the laser -the player is Marantz CD-65DX with CDM4- but I can`t find this read points for the voltage on my player. I can setup the laser by listening like you,but I want only your value of this two trimers(22K,4K7) ,because now my player can`t read any CD ,and nobody for the moment can`t help me with any picture of the CDM4 with the voltage-read points or any other instructions. And YES ,I `am sure that my laser is OK

Thanks!

Pls guys and may be
Gasho:
I can tune-up the laser with many CDs from many brands on hand with very small help from you.Pls give me the value for this two trimers ( 22K and 4K7) from your player and I can make only very fine tuning for me.If you can`t in the thread I have e-mail in the user info. Pls- It`s very importantly for me and my player.I love this player in human decency but for me now he is dead
My CDM4 is new from one bulgarian shop for old parts.
Gasho:
I can tune-up the laser with many CDs from many brands on hand with very small help from you.Pls give me the value for this two trimers ( 22K and 4K7) from your player and I can make only very fine tuning for me.If you can`t in the thread I have e-mail in the user info. Pls- It`s very importantly for me and my player.I love this player in human decency but for me now he is dead

My CDM4 is new from one bulgarian shop for old parts.

Focus trimer trim to some midpoint position , but the laser bias is crutial. Do not overtrim laser bias , you can damage it.
I did not measure the trimer position value , the player is gone by now to his master😎
I did not measure the trimer position value , the player is gone by now to his master😎
Anyone have in his hands any player with CDM4?
If anyone can give me the value for this two trimers -4K7 and 22K will be very,very,really very great ,because I can`t tune-it for any CD.
Thanks
If anyone can give me the value for this two trimers -4K7 and 22K will be very,very,really very great ,because I can`t tune-it for any CD.
Thanks

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