Just serviced one of these Philips based players (CDM4/11 and TDA1541A), recap (almost complete), cleaning, installed independent regs for TDA and 7220 (opted to not do the NOS here, it's not for me). Also did full adjustment and controlled everything. Turned out there was a smaller clamping issue (sometimes CD made mechanical noises and reading failed, but would play a disc straight when ok), so I tried to adjust the spring for the clamp, this went terribly wrong (never happened before, done this before), as the little pin where it fits on the right side simply broke off!! :O So, I installed the spring on the left side, fortunately Philips probably had foreseen this happening or, in an ideal world, it should have two of these springs, so on the left the CDM clamp and base have the pins. Well, from then on, the refusal to read TOC went worse, about half of the time (even pressed ones! seemed arbitrary, sounded like the laser was trying to read (noisy) and then it failed, the other times it would read well it would make the normal soft and smooth sound). Would play very well when TOC eventually was read, no skips, nothing.
Checked supplies, laser and laser supply - all well. Beautiful eye pattern with 2V-p-p. Even checked real laser current over drive transistor emitter resistor, within normal range. Service routine would be the same too: focussing and everything all straight, but then sometimes failing at step "3".
Then, found out that a little pressure on top of clamp in centre made it fail much less. So, figured it was in fact a mechanical problem.
Tried to change the clamp - no luck here, it's a strange rare format, it's larger than the normal CDM4 which I had as spares.
Tried fiddling around with the springs, nothing changed. Then decided to test without all the clamping, fixing the CD directly to the internal CDM part with bostix (have done this before, it works fine, but sometimes CD decides to fly into space
), and beware, it was doing the same thing sometimes! Normally, in some players I had clamping issues, this would isolate the problem.
This got me really puzzled, thought maybe something could be wrong with the lens, radial arm, focus coils, whatever, so I decided to swap the RAFOC only, from a known good CDM4/19 (or at least this is what I tested at the time, it was working!), and to my surprise, the CDM4/19 laser doesn't work in this player!!! I thought they were all more or less compatible, within the CDM4 series, only changing the motor types (this one has the hall motor, so I couldn't simply swap the whole unit). It wouldn't even focus, and no surprise here, laser voltage was only 11mV with the POT turned to max! WHY???
Took it all out again, swapped the RAFOC again, and then, while testing the original CDM4/11 with a particular CD which would almost never read the TOC (only the internal part, without drawer and clamp), I accidentally pressed the back part of the inner cdm (towards the transformer) DOWN (remember it's suspended on springs, but in this model, it's also secured with rectangular plastic parts which are screwed on at two corners, diagonally), and, how strange, it read the TOC. I maintained my fingers there (so the cdm would be slightly tilted), it would read the TOC everytime! I then tried to press slightly down the other side, too, so it wouldn't be tilted, just lowered, and still, would read the TOC perfectly! So, I installed a few washers between each of the plastic rectangles and the metal bracket of the cdm, so that the path of the spring suspension would be shortened and the cdm effectively was (in an equal way) lowered about one millimeter, but still somewhat suspended. It did the trick!! Mounted back all the rest of the mechanism (thinking that the clamping could make it worse again), but no, still working perfectly!
I've got it testing for some hours right now, hasn't failed TOC once on several different CDs, also CD-Rs, even some difficult discs and scratched, not one skip, too. This is amazing, I can't understand what happened? I mean, this lowered the CDM, yes, but it didn't affect distance to CD from laser, as the motor is on the same part. It might have affected the clamping force, yes, but being more FAR away, shouldn't it have become LOWER now? Remember that before it would help to press slightly on the center (which, btw, would also push the CDM down, so it was the same problem since the beginning, but doesn't seem to have to do with the clamp!). Can it have something to do with the suspension springs?? But why?? Maybe balancing of the RAFOC? I remember once a CDM4/19 which would only work well when the inner cdm part would have two diagonally opposed screws, NOT fitting the other two. Was mounted like this from factory! In a Technics. Maybe that's it? Would love to hear some thoughts on this, to better understand.
Hopefully the player is definitely fixed like this, still have to do further testing, but I found this so strange and odd that I had to share. Also, it might come in handy to some one some day if experiencing something alike.
For the rest, I'm going to test that spare CDM4/19 in another player when I have time, hopefully the fact that it doesn't worked in this player is really due to incompatibility and not ESD-damage, for example...
Checked supplies, laser and laser supply - all well. Beautiful eye pattern with 2V-p-p. Even checked real laser current over drive transistor emitter resistor, within normal range. Service routine would be the same too: focussing and everything all straight, but then sometimes failing at step "3".
Then, found out that a little pressure on top of clamp in centre made it fail much less. So, figured it was in fact a mechanical problem.
Tried to change the clamp - no luck here, it's a strange rare format, it's larger than the normal CDM4 which I had as spares.
Tried fiddling around with the springs, nothing changed. Then decided to test without all the clamping, fixing the CD directly to the internal CDM part with bostix (have done this before, it works fine, but sometimes CD decides to fly into space
), and beware, it was doing the same thing sometimes! Normally, in some players I had clamping issues, this would isolate the problem.This got me really puzzled, thought maybe something could be wrong with the lens, radial arm, focus coils, whatever, so I decided to swap the RAFOC only, from a known good CDM4/19 (or at least this is what I tested at the time, it was working!), and to my surprise, the CDM4/19 laser doesn't work in this player!!!
I thought they were all more or less compatible, within the CDM4 series, only changing the motor types (this one has the hall motor, so I couldn't simply swap the whole unit). It wouldn't even focus, and no surprise here, laser voltage was only 11mV with the POT turned to max! WHY???Took it all out again, swapped the RAFOC again, and then, while testing the original CDM4/11 with a particular CD which would almost never read the TOC (only the internal part, without drawer and clamp), I accidentally pressed the back part of the inner cdm (towards the transformer) DOWN (remember it's suspended on springs, but in this model, it's also secured with rectangular plastic parts which are screwed on at two corners, diagonally), and, how strange, it read the TOC. I maintained my fingers there (so the cdm would be slightly tilted), it would read the TOC everytime! I then tried to press slightly down the other side, too, so it wouldn't be tilted, just lowered, and still, would read the TOC perfectly! So, I installed a few washers between each of the plastic rectangles and the metal bracket of the cdm, so that the path of the spring suspension would be shortened and the cdm effectively was (in an equal way) lowered about one millimeter, but still somewhat suspended. It did the trick!! Mounted back all the rest of the mechanism (thinking that the clamping could make it worse again), but no, still working perfectly!
I've got it testing for some hours right now, hasn't failed TOC once on several different CDs, also CD-Rs, even some difficult discs and scratched, not one skip, too. This is amazing, I can't understand what happened? I mean, this lowered the CDM, yes, but it didn't affect distance to CD from laser, as the motor is on the same part. It might have affected the clamping force, yes, but being more FAR away, shouldn't it have become LOWER now? Remember that before it would help to press slightly on the center (which, btw, would also push the CDM down, so it was the same problem since the beginning, but doesn't seem to have to do with the clamp!). Can it have something to do with the suspension springs?? But why?? Maybe balancing of the RAFOC? I remember once a CDM4/19 which would only work well when the inner cdm part would have two diagonally opposed screws, NOT fitting the other two. Was mounted like this from factory! In a Technics. Maybe that's it? Would love to hear some thoughts on this, to better understand.
Hopefully the player is definitely fixed like this, still have to do further testing, but I found this so strange and odd that I had to share. Also, it might come in handy to some one some day if experiencing something alike.
For the rest, I'm going to test that spare CDM4/19 in another player when I have time, hopefully the fact that it doesn't worked in this player is really due to incompatibility and not ESD-damage, for example...
Finally found time to test the spare CDM4/19 in another player and it is working fine, just like last time I had tested. So, this confirms with 90% probability of being right (there's a very remote possiblity that I did something wrong while swapping the RAFOC, but this is not the first time I do it, so highly unlikely) that the laser head (RAFOC) of the CDM4/19 does NOT work in a CDM4/11 mech.
Also, good new regarding the CD-65DX: my strange hack is working fine, player has been working reliably, reading about any CD I throw at it. On some rare occasions, I found one disc which not always the TOC is read. But when it is read, the whole disc plays without any hickups. You can also change tracks without hassle. The only thing that was impacted negatively (and which is totally logical) by the hack is the stability to impacts or vibrations to the case of the player. As the springs travel is shortened, it logically flaws the suspension and becomes vulnerable to impacts. But as this is a stationary player, this is not a problem, it's not that sensitive, also. So, I still can't figure out why this hack was necessary, but it works. Might help someone in the future.
Also, good new regarding the CD-65DX: my strange hack is working fine, player has been working reliably, reading about any CD I throw at it. On some rare occasions, I found one disc which not always the TOC is read. But when it is read, the whole disc plays without any hickups. You can also change tracks without hassle. The only thing that was impacted negatively (and which is totally logical) by the hack is the stability to impacts or vibrations to the case of the player. As the springs travel is shortened, it logically flaws the suspension and becomes vulnerable to impacts. But as this is a stationary player, this is not a problem, it's not that sensitive, also. So, I still can't figure out why this hack was necessary, but it works. Might help someone in the future.
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