CD Player in distress: Philips 3 disc carousel changer,

[shakalnokturn]

Ahhh... Replied too late, no great loss anyway.
If I remember correctly more current is clockwise, I was going to say you should be able to measure the voltage across the blue 6R8 resistor to know the current.

As for the schematic I'd expect a CC source with maybe a (problematic) BC337 or BC338 to drive the laser (transistor with collector in blob of glue), it does appear to have some optical feedback from a photodiode for
output regulation. (Attached to the base of the same SOT-23 as the trimmer.)

[laneboysrc]

1) Turns laser ON, I can see it.
2) Then moves the Focus motor / lens up and down, once.
3) turn on the spindle motor : disc is rotated by about a quarter of a revolution, no more no less. Just a quarter. This lasts only a fraction of a second of course.
4) then it fails to detect the disc/read data I assume, because the changer then switches to the next disc, and the whole cycle repeats.

Ah. This means the drive can not achieve focus. The firmware initiates the ramp, since the chipset does not report "in focus", the MCU kicks the disc a bit just to ensure that it is not just a bad spot on the disc, then tries focusing again.
As others suggest, most likely the drive is toast.

[Vince]

Ahhh... Replied too late, no great loss anyway.

Yeah not the end of the world. I prefer to lean and do mistakes on old junk rather than a valuable quality unit...

If I remember correctly more current is clockwise, I was going to say you should be able to measure the voltage across the blue 6R8 resistor to know the current.

Oh yes that would have been a good indeed ! I would have done it maybe.. had I already reversed engineered the flat flat circuitry..... next time maybe ! 

As for the schematic I'd expect a CC source with maybe a (problematic) BC337 or BC338 to drive the laser (transistor with collector in blob of glue), it does appear to have some optical feedback from a photodiode for
output regulation. (Attached to the base of the same SOT-23 as the trimmer.)

There is one thing that puzzles me and keeps me from reverse engineering the flex... don't you see something strange if you zoom on the flex ? On many locations, there are what look like holes punched into the flex, that cut traces, and the trace hence goes nowhere ? What's up with that ?! Guy is confused....

[Vince]

Ah. This means the drive can not achieve focus. The firmware initiates the ramp, since the chipset does not report "in focus", the MCU kicks the disc a bit just to ensure that it is not just a bad spot on the disc, then tries focusing again.
As others suggest, most likely the drive is toast.

OK... so I will order a new complete assembly, not just the optics, so as to replace as much of the mechanical stuff as possible at the same time...

While the part is making its way to me, a few days if I order from Germany /  Europe, I will try just for fun to reverse engineer the circuitry on the flex.. if I can make sense of all these holes in the flex, that is...

[shakalnokturn]

There is one thing that puzzles me and keeps me from reverse engineering the flex... don't you see something strange if you zoom on the flex ? On many locations, there are what look like holes punched into the flex, that cut traces, and the trace hence goes nowhere ? What's up with that ?! Guy is confused....

The diodes involved are sensitive to ESD so maybe a safety during assembly, once the flex is populated and ready for final test I imagine the shorts are punched away.
After final test the end connector will be fitted with a grounding clip.

Other pickups like the KSS series come with a solder bridge that must be opened after replacement.

[Vince]

Hmmm interesting !

The old man just gave me the green flag for the new pickup.. .so I just bought one from Ebay Germany, the full transport, 20 Euros shipped :

https://www.ebay.fr/itm/231334211805

Can't wait to receive it ! 

[Vince]

Received the new pick-up assembly... NOT happy with my purchase ! First time I have been let downby a German Ebay seller... I gave you the link above.. I don't recemmend him ! 

- Packagin was distrous : ZERO padding ! That sensitive little pick-up was wrapped in a single thin layer of plastif film, ie nil, then placed in a box 3 times its size ! It's a miracle the poor little thing arrived intact !

- The supposedley NEW part... clearly is NOTnew at all ! .. the sticker on the radial motor (the one with the worm screw), hardly looks "fresh", more like it's 25 year old ! The flat flex is harldy smooth and shiny, and it even has  kink/damage onj the inner edge where it does the 90° turn to meet the tiny PCB on the pick-up ! Luckily the copper trace located on the edge, looks intact, mostly anyway.  And lastlt : the terminal for the two motors (spindle and radial), and also the contacts that detect that the head is at the begining of the disc... all these terminal had a solder blob, and strands of wire in them ! 

So clearly that assembly is second hand, was salvaged from God knows where, and whoever did it, simply cut all the wires, faster than desoldering the wires I guess ! 

.. but I fitted the assembly to the drive anyway, hoping it would work and call it done... didn't feel like battling with the seller and get my 15 euros back then ordering another one from another German seller, waiting again,  and maybe getting the same problems...

So, after 3 hours of fighting with the mechanical guts of the carousel, then upon painful reassembling the thing using lots of trial and error, realizing that I did not even have to touch any part of the carousel to begin with !!!  ...well I eventually managed to replace the bloody pick-up, get the carousel back in one piece and working properly again... and yes, IT WORKS !!!! 

So it was indeed the pickup that was bad, causing zero signal to get into the HF amplifier.I probed once again the output of the amp, and see what I get ? Yes, I now get that lovely eye diagram pictured in the manual !   
Sure enough I didn't get anything like that before !
So, I now know what kind of signal I am supposed to get out of a pickup !

The amplitude as you can see is not stellar, around 1,0 to 1,2Vpp. Not much more than the 0,8V minimum required in the manual. So I guess the laser is tired since it's obviously an old second hand pick-up   
But well,, 1,2V is still 50% more than 0,8V, so technically it's quite a bit better eh, what do you say from your experience ?

At any rate, it works, just fine. Reads all my 25 years old CD's just fine, and is responsive.

Anyway, I don't need this horrible stereo system to last for 10 years.... my dads only need the CD part of it, for it's changer functionality. Doesn't use the vinyl turntable, nor the tape deck, nor the radio tuner...nothing but the CD changer.

So I thought, best to throw away this horrible stereo, and instead find a nice stand alone CD changer like the old Philips, or slightly newer maybe, mid '90s stuff. A cheap broken I could repair for him. Then he would just need an amp to go with it... but he already has one ! An audio nut gave my dad an old Cabasse amplifier to repair. Was high-end but the guts of it were terribly prehistoric, electronics-wise. So he was able to repair it and as a thank you, guy offered him an old " Cambridge " branded amplifier ! So, he already has an amp... just need to find him a nice CD changer to stack on the of it, and good-bye the old crappy Stereo system !   


Anyway, thank you all for your precious help ! That was my second CD player repair, quite different than the swing arm. Learned more new stuff then, great ! I feel now quite confident tackling my future third repair, if the old man approves my plan ! 

[shakalnokturn]

Nah, not new! Looks like a shameless rip-off...

The 1V-1.2V eye pattern as far as I remember is good though, you shouldn't expect much more.

One thing I'm unsure of from your photos is the disc clamping on the spindle motor.
The original is a magnetic clamping, the replacement looks like a push-on by hand version that would have been used in portable top-loading equipment, smaller motors may also point that way. Can you confirm the CD does not clip onto the spindle on the replacement transport?

On that website you must avoid, I came across a Philips 5CD carousel sold as not working for 5€, it also uses the CDM12 transport, from my limited experience with the model the belts need changing. Advert number is 1877334080, you know, just in case you need to make an exception 

[Vince]

One thing I'm unsure of from your photos is the disc clamping on the spindle motor.
The original is a magnetic clamping, the replacement looks like a push-on by hand version that would have been used in portable top-loading equipment, smaller motors may also point that way. Can you confirm the CD does not clip onto the spindle on the replacement transport?

Oh, trouble again  ?! Oh no.... I had no idea about this clamping thing. I sure did notice a difference in this area between the two parts, but didn't think much of it, not knowing any better ! It was a CDM12 so well... didn't know there variations ! 

I can't confirm anything as I have already put the whole system back together, back in its box ready for my dad to pick it up ! 
All I can remember, if that's any relevant, is that on the new transport, the CD while rotating, was wobbling. It was not spinning in a flat plane so to speak, if you see what I mean ? Consequently, the amplitude of the eye diagram was wobbling up and down accordingly, in unison with the disc as it was rotating.  Is the disc supposed to spin perfectly flat ?

OK... I know what that means... will have to take the whole thing apart again, pull the CD player remove the transport... take out the pick-up / optics, and fit in the old transport, so as to reuse the original clamping setup, and motors (which indeed were much bigger)

OK then....  well at least now I know how to take it apart, so should be fairly quick and painless...

  On that website you must avoid, I came across a Philips 5CD carousel sold as not working for 5€, it also uses the CDM12 transport, from my limited experience with the model the belts need changing. Advert number is 1877334080, you know, just in case you need to make an exception 

Hmm so tempting !!! Couldn't resist. Bought it 5 minutes ago... a minute later at most, sale got cancelled and seller messaged me to say "sorry, alrady sold, was sure I had removed the ad... done now, sorry ! ".
Bummer...

Oh well...

Old man just told me he is waiting to finish the renovation of a room in his house, where he will install his Cambridge amp and CD player. But the renovation is going slowly, he is 75 year old after all... He expects to have finished by the end of the year.  So that leaves me plenty of time to find out about what CD changers were available in the '90s, which model were good quality, and hunt for one.
Hopefully I can find a model with cassette rather than a carousel... working on this carousel made me hate them for life. Such a horrible design compared to a cassette. I don't even understand why people buy carousel players    So slow and cluncky and noise, and a nightmare to work on... brrr.   Had a quick look on ebay France.   old CD players are so cheap it's barely worth fixing a broken one 
So much to choose from in the 35 to 75 Euros bracket.

I searched for my old swing arm, CDC486, found only one for sale, not even in France, and around 150 Euros ?! 
Either a glitch in the Matrix, or are they becoming collectable somehow ? Starting to stand out of the crowd as time passes ?
Will hang on to mine dearly ! 

[shakalnokturn]

If the CD was extra wobbly, I suppose the clamping mechanism had enough strength to get the CD over some but not all clips.
CD's never spin perfectly flat and that's usually more noticeable on the outer edge. The focus servo must be able to take care of that. I'm surprised you got no read errors on outer tracks if the disc was not correctly clamped.

Other than Philips I think that Fisher, Pioneer, Kenwood, Onkyo and Denon made some CD cassette changers.
Sony made some large CD jukeboxes that ranged from 50 to 400 CD's (that's still under 300GB of optical storage ) capacity depending on model.

[Runco990]

I figured the pickup was bad....   Like I said, replaced TONS of them.

The spindle can be just pulled off the motor and swapped.  You don't need to change the mechanism.  It's just press fit.

[shakalnokturn]

The lower part of the disc clamp can be removed from the spindle motor, usually I absolutely avoid that though because in some cases it's pain re-fitting it at the optimal hight for the focus servo.

I'd definitely go with Vinces's idea of swapping the laser assembly onto the original transport here.

[Vince]

OK !

2 hours of work later... it's fixed.

Taking the hifi apart again to pull the CD player out of it was a  2 minute job, not that bad in the end.

Removing the transport took ... 5 seconds. I definitely learned from my first painful experience here ! 
No more taking the changer mechanism apart, no more cursing for 2 hours while trying to figure out how to put it back in one piece again.
Nope... no need to mess with the changer. just unscrew the 2 metal brackets that hold the transport... it won't come out oh crap, what the... ah yes ! ... pull the tray open by hand, half way is enough. Just enough so you can get your hand on the exposed gear of the changer underneath the tray. rotate gear by hand, so as to move the transport up and down. Once fully in the down position, yes, it will come out just like that ! 

Then need to remove the old pick-up.... removed/unscrewed the finger contacts near the spindle, to give better access. Also popped off the big plastic gear that links the worm screw of the radial motor, the the pickup assembly. This way you can easily slide the pickup from one end of the race / metal rod to the other, to get better access to the ends of the race.

Then tried to remove the two tiny white plastic clips that hold the ends of the race in the transport. Big mistake, the first one shattered in pieces in an eye blink ! Yes, I WAS super careful and delicate.. but still !    So looked at the second clip more closely... ahhhh I see ! It's NOTa clip ! It's molre like a dove tail key that you slide along the race and that locks into the transport ! so you justs need to take tweezers and slide the key inwards of the race, and that's it, it instantly and smoothy comes out ! 

But... what to do with the broken one ? Can't salvage one from the "new" (used..........)  transport, because... well it's not the same ! It uses a different system to hold the race into place. A very dude way I should add !  One one of the race is just shove unto a hole, and the other is "secured" in place with just the edge of a screw head pushing on it ! See pictures below... horrible.

Old transport is much more refine I find. Even has little rubber ring on the ends of the race so they fit snugly into the transport, as well as providing some extra resilience to vibration, I guess.
So had to fix the old transport.. how can I keep the race in place ? A dab of hot glue did the trick just fine !  Don't judge me, please !!!   
Had to do with what I had at hand.... needed a quick solution.  Of course I did not use the "gun" supplied with the hot glue sticks. I just grabbed a bare stick and melted it with my hot air rework station. Gave me enough control to achieve enough "precision", ahem, to not butcher the transport. Not a fine piece of art, but it does the job.

Yes... I say it does the job because somehow, somehow... after putting the drive all together again, it worked just fine !!!
Can'"t believe it. maybe I am so worthless after all ?!  Or just lucky...

Not sure how long the hot glue will stay in place, but it looked plenty strong enough the tiny loads it needed to handle.
At any rate, this is a junk hifi may I remind you... we just need to keep it going for a year or so, then we will replace it with a proper stand alone CD player. I am quite confident the ho glue will last for a year... a more than that.

Was all this, worth the trouble ?  I say yes :

1) Learned some more stuff, more hands-on experience with pick-ups.

2) Using the original magnetic spindle DOES make things MUCH better : ZERO noticeable wobble compared to the new transport ! What a difference that made !     Lesson learned ! Thanks ShakalNokturn for bringing this point to my attention !

[Vince]

On another note.. if any of you know anything about crystal oscillators for mechanical clocks ? Need to replace one and I have no clue where to get one ?! 

https://www.eevblog.com/forum/repair/crystal-oscillators-for-mechanical-clocks-can-they-be-bought/msg3423850/#msg3423850

[Vince]

Eh ?! Are you on crack ?!

Didn't know forum could be susceptible to spam ?! I guess I need to get out more, first time I see this...