Vintage CD player repair : Philips CDC 486 6 disc changer.

[Vince]

Hi all,


I just got this old CD player shipped to me for repair, just unboxed it an hour ago....
It's from my dad. It must be from 1990 or close to that. At least that's when he bought it. I was 10+ years old at the time IIRC, nostalgia, a piece of my life... I vividly remember playing my first audio CD's on this thing,  I absolutely want to fix this thing. I really hope it can be fixed !

Trouble is that I am not at all into audio stuff in general, no particular knowledge in this domain, and at any rate I have never ever had to fix or even open a CD player before. This is my very first CD player repair... so basically I don't know what I am doing !!!     

... hence why I thought I would post the repair on here, so that hopefully more knowledgeable and experienced people can help me out here and there... and keep me from doing fatal mistakes perhaps...


As the title says, it's made by Philips, model number CDC486.  It has a cassette that can hold 6 discs, stacked on top of one another, each in its own little tray/holder. There is a hinge on which the trays pivot.

My 75 year old dad had a go at it himself, downloaded the service manual.. but he failed to fix it. Now asking me if I could rescue the thing... if I fail, he will as usual say I am worthless and a disappointment ! That's how he is... so I really hope I can manage to fix it, to prove him wrong ! ....

The service manual, is over 20MB so unfortunately I can't post it here. He sent it to me on an SD card along with the player...
Maybe if I can find it online I could put a link to it here.

Anyway, here is what he told me as far as symptoms go : " Son, the player fails to spin up the disc, the motor just won't spin. I checked the motor itself, it's not faulty. ".

As for me, I spent only 5 minutes on the thing, to try and witness the symptoms... and turns out I disagree with him from the get go ! From what I can see, sure the disc does not spin, but to me it seems "normal" : the player acts as if it doesn't even detect that there is a disc present ! So logically, it won't even try to spin the disc... CQFD.

Here is what I did exactly :

- Removed the top cover of the player, so I can see the internals working as I am testing it.
- Loaded a CD in the first slot of the changer. 5 remaining slots are empty.
- Powered up the player.

Then just after power up I recorded a close-up video of the internals doing their thing. It's only 20 seconds long don't worry...



I apologize for the background music polluting the video, my computer playing music, forgot to mute it before recording the clip 

From what I can see :

- The cassette gets "cranked" so as to line up the first tray with the read head assembly.
- Extracts the tray from the cassette and loads it.
- The reading head giggles a few times quickly then stops.
- Player remains inactive for a couple seconds, nothing happens.
- Then it puts the disc back into the cassette
- Cranks the cassette to select the next slot (which is empty), opens up the corresponding tray
- Again giggles the head
- Again freezes for a couple seconds
- Again puts the tray back into the cartridge

That cycle gets repeated 6 times until all slots have been checked and the player gives up.

So basically, the player behaves EXACTLY the same whether or not there is a CD present in a given slot. Disc or not, it giggles the head, waits for a couple seconds, then switches to the next slot.

So that's why I am thinking the problem is simply that the player fails to detect the presence of the disc, hence logically does not spin it, and goes on to check the other slots in the cartridge, hoping to find a disc somewhere.

So... I guess I will try to find all I can in the service manual about the detection mechanism... how it's implemented from a mechanical and electrical point of view, where to find it exactly, how to get to it / dismantle the drive without damaging anything, etc....

Any practical advise much appreciated of course !

I meant to post a couple piccies but that failed somehow, the forum greeted me with an error message saying, I quote :

" Your attachment has failed security checks and cannot be uploaded. Please consult the forum administrator. "

Security checks ?! How dangerous can a CD player be ? 
How DARE I want to post pictures of a 30 year old broken CD player, silly me !!! 

[Vince]

Looks like the first of my two pics DID make it ! It's only the second pic that triggers the forum and won't make it no matter what... go figure. 

[shakalnokturn]

Hello Vince.
You must fix this, can't let the old man be right, besides it's a historical swing arm pickup... I am a bit of a fan of the Philips CDM 1-4, 9 stuff.

What you're seeing is failure to read the disk index that can be caused by a number of things, but the basic flow is to load a disc, bring pickup to center of disc, spin disc, turn on laser, try to focus on disc, try to find track, seek TOC.

So any failure in laser output, insufficient optical return, servo loop or electromechanical faults can give that result.

Starting points:
Is disk engaged correctly and camped to the spindle?
Is lens clean? (Beware of smoke particles)
Is there laser output?
Is the spindle motor spinning freely? (Beware of bad brush-collector contacts or 1/3 shorted winding)
Is the arm spinning freely? (This is a common trap, the grease on the pivot balls can go hard, the magnet can also attract small magnetic objects that can jam.)
Is the focus mechanism working? (I've seen some with broken spring hinges.)

Other common problems are bad solders and bad capacitors.
I've also seen a couple of hard to spot broken flex cables on the pickup assembly and bad TEA8808T servo IC's.

[Miti]

To add to the shakalnokturn's list, check if the disk is at the correct distance from the lens. I've seen CD and DVD players that were dropped and the spindle moved on the motor shaft.

[Whales]

Do CD drives bother to check for a disk before spinning up?  I thought they always tried to spin, then perhaps gave up if they didn't detect an inertial mass (ie too little current draw).

If the motor is not spinning then trace back from there.  See if there is a dedicated motor controller, or just a few transistors, etc.

I once had a DVD player that used a resistor between the motor & the motor controller.  It had blown open (possibly due to a jammed/misinserted disc?  or mechanical fatigue, because it was the biggest SMD discrete around?) and replacing it kept the unit running for several more years.

[paschulke2]

First of all: Are you sure you loaded the discs in the correct orientation? A lock at your photo tells me that the orientation has to be "label down", which is unusual. A look at the video in slow motion makes me think that maybe you inserted the CDs with the normal orientation (label up).

The typical sequence after loading a disc is:

(1) Check the position of the loader or tray (with a switch).
(2) If ok, turn on laser and try to focus.
(3) If focus is ok, spin the disc and try to read the TOC.
(4) Either stop and display the TOC or start to play the disc.

In your case (1) is ok (because it moves the laser head and tries to focus). Maybe (2) fails because of the possibly wrong orientation of the discs.

If (2) stills fails with correctly inserted discs, you will have to check whether the laser emits light and if it can focus properly.

[Vince]

Wow, thanks a lot everyone of you for your help, much appreciated ! 
Shakalnokturn I sure vivdly remembered that you had a soft spot for these old Philips CD players, hence was hoping you would offer your help, thanks for doing so then ! 


So, to sum it up :

1) I was wrong then, no simple "CD presence optical switch", so no easy fix, bummer ! 
2) It can be a million different things I have mostly no clue or experience with,  great ! 


As far as smoke/dirt on the lens : non smoking dad, and clean house...
As far as mechanical damage... the player has spent the last 30 years in the same comfy living room, never had "accidents", a peaceful life.

I noted that you don't all agree on one point : is the disc supposed to spin before, or after focusing is attempted ? I guess that means it depends on the particular drive/product...

As far as putting the disc the wrong way around.... OOPS, yes I did !    Indeed I put it label up, but indeed it's supposed to be label down, the head being atop of the disk. With the disc the correct way around, the CD player behaves 100% the same, nothing has changed.

Lens cleanliness ? It facing down, I can't even see it ! 

Disc clamping : can't see much of what's happening in there... once the player has drawn a tray from the cassette, the tray hides the bottom of the mechanism of course, so I can't see if anything underneath the tray is pushing upward to clamp the disc to the motor...

Laser working ? Here again, with the head facing downward, I can't see squat  How easy is the laser spot to distinguish ? Is it a large blurry blob that reflect off of the surface of the disc, and it is absolutely impossible no to see it ? Or is it a tiny 0.1mm spot ? I can't see anything (anything obvious I mean) reflecting on the surface of the disc. I also had a look when it's trying to read an empty tray : the interior is all all black plastic parts, so I turned all the lights of in the room to make it dark, and stuck my nose in there, thinking I would be able to distinguish a tiny laser spot easily on a black plastic part.... but I didn't see anything.


OK. Before I can do any troubleshooting I need to print all the schematics and block diagrams in A3 format at work so they are about readable. Will do that tomorrow. Until then I can only do thought experiments !


One question : this 2 second delay we witness, after the head has finished moving, and before it switches to the next disc... what does it correspond to ? What is the drive (trying to) doing during that time ? At first I thought it might correspond to the time during which the disc is supposed to spin, and during which teh drive is trying to read the disc. It it fails after 2 seconds of trying, then it gives up. However if that were the case then why would it do it even for trays where there is no disc, and therefore where we are sure it can't possibly focus.. if it can't focus why would it wait 2 seconds trying to spin the disc (or whatever), instead of just skipping immediately to the next disc ? Seems odd / inefficient to me...
That would make sens however if the focusing is attempted AFTER the disc is spinning... in which case during these 2 seconds, maybe it is trying to spin the disc but it just doesn't work. Hence investigating the spindle motor might still be useful....

So, questions and more questions ! 

Tomorrow once I get the schematics printed, I could start with :

1) Check all numerous power supply rails, first things first eh ! You never know... mayube the laser is indeed not working since I can't see anything, and maybe it's powered by a dedicated power rail, hence only the laser would stop working but it would not keep the rest of the circuitry from working.

2) Check the circuitry that drives the laser diode. According to the schematic it's quite simple. The decoder IC drives the LED via a humble NPN transistor (a BC338) fed by +10Volts. It also involves a 33uF electrolytic cap.... hum...
Could also test the laser diode itself with a basic diode test...
That 10V rail is not even listed as coming out of the 8 rails that the power supply board produces... so that's one more rail ! Will have to figure out how and where it is generated...

3) Check the turntable motor drive circuitry... it's made of a couple op-amps, from an NJM 4560 chip, whatever that is... then the final drive is a bi-polar push-pull stage, powered at the top by....oh, guess what... that same 10V rail that powers the Laser LED !
And... I see that the focus motor is also powered by that rail ! Ahhhh.... could it be just a faulty rail then ! That would be great ! 
... oh no, spoke too soon ! On another schematic page I see that the motors that handle the cassette and trays, also use that rail... and those motors work just fine. Oh well... 
Still worth checking all rails of course, and local power supplies. You can't rule out local problems... just because the 10V rail works doesn't mean it gets to each and every place as it should... doggy flat flex, doggy local electrolytic cap, what have you....


I will try to attach the schematic but not easy. Even single sheets are too large to satisfy the requirements of the forum. If I compress a page enough to get below 500KB, then it's a bit hard to read :-/
I think best compromise would be to crop the schematic to retain the most relevant bit. This way picture will be smaller so I would be able to retain a high resolution / legibility without exceeding the 500KB file size limit..... just a bit time consuming that's all ! 

[Vince]

OK here goes the overall block diagram for the player. Cropped it a little bit to removed the margins/blank space all around it, converted it to black and white, and compressed in JPEG as much as necessary to get the file down to 500KB... it's still about readable.  The interesting stuff is at the top left of the diagram : the laser/head and spindle motor related stuff.

[Vince]

Oh... just realized that the file size limit is not 500KB but a huge 4MB ?! 

So I could have just attached the PDF sheet directly instead of trying to convert it to picture and spend time reworking it...

So here is the original PDF sheet, for the schematic page discussed above. 850KB... I normally would not dare attaching such a huge file so I apologize for those on dial-up or dodgy DSL or like me with a defective 4G modem...

[paschulke2]

Tomorrow once I get the schematics printed, I could start with

… the service mode of the CD player and the flow chart in the service manual (page 4-1). If I read the service manual correctly, the service mode is activated by pressing "Time/Track", "Next" and "Previous" while turning on the CD player.

[Gyro]

My 75 year old dad had a go at it himself, downloaded the service manual.. but he failed to fix it. Now asking me if I could rescue the thing... if I fail, he will as usual say I am worthless and a disappointment ! That's how he is... so I really hope I can manage to fix it, to prove him wrong ! ....

That's pretty harsh, particularly if he's had a good go at screwing it up himself!

I too am a fan of the old Philips swing arm mechanisms they're pretty solid with no gears on the tracking mechanism to get gummed up - I don't know about the changer mechanism though, I've never touched one of those.

From the video, the head is trying to find focus on the disc and failing, on a single disc model, it would just stop and display Err but presumably it does something different on a changer. Hopefully your dad hasn't messed with the offset and laser current pots although the lasers are reasonably robust and the adjustment are in the manual. Don't touch them yet though.

One possible thing that could make you look like a genius... that 33uF electrolytic capacitor, 2521 in laser drive circuit is notorious for failing in all of these early players. It's a Philips axial one which either dries out or becomes leaky, leading to current instability. Replacing this with any decent low leakage electrolytic could well just bring it back to life. with no adjustment needed.

I treat that as a go-to replacement before looking any further.


P.S. If all else fails, tell him he should have been a better Father!

[Audiorepair]

I don't have a huge amount of experience fixing CD's but I have repaired quite a few.

First of all, you HAVE to clean the lens.  Non smoking house, doesn't matter.  This is an old machine, it WILL have some kind of coating on the lens reducing effectiveness at best.

Second, the usual case is the CD tries to focus the lens on the CD.  If it detects a disc it will spin the motor and try and read the TOC.
If if doesn't spin the disk, either it doesn't see the disk or (rarely) the spin motor system is not working.

Third, on almost every occasion I have had a CD player for repair, if it doesn't see the disk, then either the laser needs cleaning, or the laser just doesn't work any more, and there is usually a cheap generic replacement you can try/fit.
(Though by the looks of things, the laser assembly in your machine is not generic)

Fourth, you would have to be crazy to try and troubleshoot the electronics without actually cleaning the lens first.

[Vince]

Thanks again for the info, I really need each every bit of advise you have to offer, as I am soooo clueless.

My dad is now thaaat horrible... I ha ve learnt to deal with him... he is the way he is that's all, as we all are. No point in trying to change him...  I know he loves me deep down, so that's alright. He certainly would not have massacred the player. He is very meticulous. Him failing to fix it is just due to not  being an electronic guy that's all. He is an excellent electrician, his core skill set, and learned the basics of electronics for work as he had too, and was interested anyway. However he doesn't have a lab nor tinkers with electronics. So he did what he could with his limited knowledge and tools, ie very little.

Made some progress :

I removed the bottom cover of the player, a pretty thick and heavy sheet of metal.
This gave marvelous access to the bottom side of the mechanism : I can now see the spindle arm, which works just fine and is very strong thanks to a healthy spring forcing it to clamp the disk. So I don't think that's an issue.

I cleaned the lens of the laser. Didn't know how to do it so checked Google a bit, found lots of Youtube videos. Just rubbing a cotton swab flooded with pure alcohol, ie IPA for us electron people. At first I didn't see any contamination on the lens.. with my naked eye, but cleaned it anyway of course, just in case.

Good news : it DID make a difference. No it still won't spin / detect the disc, however now the player reacts DIFFERENTLY with the tray that contains a CD, compared to the empty trays.

Now, instead of moving the head and then stopping for 2 seconds, here is what it does :

For one second, it moves the head but almost... imperceptibly so ! Unless you pay extremely close attention, you won't even notice it... but it does do extremely tiny movements, I am sure of that. Then I can see the focus servo move up and down for a second or two, it's trying, it trying. Then it stops moving and and I hear a single and very faint "bip" sound. Not from any speaker of course, just something somewhere that somehow make a beeping kind of sounds.. no idea what it could be.
Then nothing happens, it stays there sitting for..... MUCH longer than before, like I don't know, didn't yime it.... 10 seconds maybe ? Significantly longer than the 2 seconds it did before.

So.... cleaning the lens definitely made the thing behave differently. As if it works well enough for the player to actually TRY for 10 seconds to read something, before giving up.

I still can't see any hint of the laser spitting out any light. Having access to the underside of the unit does not help since the tray gets in the way. So either it's near invisible, or the laser just doesn't fire up. So it's high on my list of things to check. Thanks for the tip on its 33uF cap, will check that for sure. Maybe it's indeed causing very low light emission, hence I can't see anything with my naked eyes. However I guess it must be spitting out SOME light... otherwise cleaning the lens would not have made the slightest of difference, logically...

So the laser circuitry is high on my suspect list now...

Reading your messages, I finally realized what you all meant with that "swing arm" expression... that refers to the way the head is moved  I think.... obvious for those in the know, not for me the clueless. Yeah that's right, now I come to think of it, most CD players I have ever seen (as a user I mean), moved the head in a straight line using rails and worm screw or something...
Hmm, so these old Philips were the only players to use this mechanism to move the head ? Guess they patented it so nobody else could use that. So that makes my childhood CD player even more special then ?! Hmm... I am loving it a bit more now, definitely want to fix this piece :-)

Hidden Service menu : tried the magic ket combination and it worked ! However the LCD display is supposed to show " US 1 ". If not, flow chart implies it's faulty. In my case I see " US 5 " not "US 1", so not good I guess....
I noticed while playing with the keys on the front panel, that although it is not documented, pressing the "forward" search key shoots the read head all the way to outside of the disc, while pressing "backward" brings it back to the center the disc. Or the other way around can't remember. Also noticed that while those keys are being depressed, for a plit second only then, the display changes for " US 0 ". Whatever that means.

Those flow charts are rather cryptic I find...
From what I understand they tell you to use the remote control to shoot IR light into the 4 photo diodes on the head, to stimulate them and take measurements...
My dad forgot to ship me the remote control... I guess any remote would do, but I do'nt have any, no TV here...

Anyway, thanks to all your advice and some tinkering, I am already much less clueless than I was just 24hours ago..
This drives looks less and less complex and mysterious, as I spend time looking at it up close. Things are starting to make some sense....

Laser subsystem is now definitely my main suspect, will investigate in this direction...

[Miti]

All CD players that I've seen so far use red laser. You should clearly see red light coming out of the lens.

[Vince]

OK thanks... then in this case the laser most definitely is not working as it should... either the LED itself is toast, or the circuitry driving it is kaput, starting with that 33uF electrolytic cap as prime suspect... will work on that tomorrow. Going to bed for now, almost 11PM and alarm clock set to 5AM tomorrow morning...

[Vince]

23:15... last minute update before going to bed... I just could not help but have another go at trying to spot the laser light from underneath the player, repairing stuff is a disease, I need to seek help I think...

At first glance it looked like even from underneath you could see shit, but looking more closely, there is a tiny spot where you can just about see the lens, if you stick your nose on it and look at tit pretty much dead on.. which is not advisable of course, so I looked at it at a very slight angle. Doing so, and while the player of course is working on an empty tray, I CAN see the laser ! Red indeed. So it's not completely dead as I assumed. However it's so faint that you really to work at it to notice it.
You have to look into the lens and you can just about notice a tinnnnnnny red spot in there, so tiny that the diameter of the lens, in comparison, looks like the milky way galaxy !    Is it supposed to be so incredibly minuscule that you can barely see it ?

Doing that, I can now gather more information : the laser is fired up only during the second where the head giggles. During the 2 second pause that follows, the laser is turned off. So, this 2 second pause definitely is not supposed to see the spindle motor turning... so no idea what the player is doing during that time.

[Audiorepair]

Normally the red laser is easily visible at quite an angle, particularly if you blow some smoke or something down there.

Yours appears to be almost non existant.


The player will be thinking:

Turn on the laser and jiggle the lens up and down and see if you can focus on the disc.
2 seconds later, no focus attained.
OK, so there is not a disc in there.
Next.

[Haenk]

that 33uF electrolytic capacitor, 2521 in laser drive circuit is notorious for failing in all of these early players. It's a Philips axial one which either dries out or becomes leaky, leading to current instability. Replacing this with any decent low leakage electrolytic could well just bring it back to life. with no adjustment needed.

I treat that as a go-to replacement before looking any further.

Confirmed. Any of those blue axial ones from Philips should be considered dead and should be replaced.
(I had a larger number of NOS of these, I checked all of them, and a very low single digit percentage was still in spec, about 90% or so were less than half the capacity. The all went into the bin...)

[Gyro]

Err, just a safety point guys - the Laser in a CD player is INFRARED, not Red. Yes you can usually see a dull Red glow if on axis, but that's the eye's response to the IR energy. The IR energy is much higher and can cause eye damage if you aren't careful - with IR, you don't get the benefit of the blink response to protect your retinas!

The Manual (and usually on the plastic inside too) has specific Laser exposure warnings about minimum viewing distance, not getting on axis etc.


DVD players are the ones that use Red Lasers and Blueray, Blue ones.

[Haenk]

Yes, IR. You can check with the camera of your smartphone. Watch at an angle, don't use your eyes

[Circlotron]

Yes, IR. You can check with the camera of your smartphone.

iPhones have an IR filter on the main lens but not the selfie lens. At least that's the case with older ones. Check first whether is shows the IR LED on a remote.

[Circlotron]

if you stick your nose on it and look at tit pretty much dead on.. which is not advisable of course,

That's true. Depending on who it is you could end up getting your face slapped.

[Miti]

Err, just a safety point guys - the Laser in a CD player is INFRARED, not Red. Yes you can usually see a dull Red glow if on axis, but that's the eye's response to the IR energy. The IR energy is much higher and can cause eye damage if you aren't careful - with IR, you don't get the benefit of the blink response to protect your retinas!

The Manual (and usually on the plastic inside too) has specific Laser exposure warnings about minimum viewing distance, not getting on axis etc.


DVD players are the ones that use Red Lasers and Blueray, Blue ones.

I’ll be honest, I repaired many CD and DVD players long time ago, but I didn’t know that the laser is infrared. The main fix, particularly for DVD players was to replace and adjust the current (IIRC) in the laser module. There was a service procedure to do that. The laser in CD players is divergent enough that, if you don’t stare directly at it from a short distance, and I don’t know how and why you would do that, it is not dangerous. Proof is, my eyes are still fine ... well, for my age.

[Haenk]

Adjusting (raising) the laser current is usually a short-term fix - one might squeeze out a couple of months until they completely burn out. Not recommended as a long-term fix...
One might have to fiddle with tracking and focus, this requires a service manual and the proper service CD is highly suggested.

The smartphone cameras have IR filters installed, but those are nowhere near 100% filter efficiency, so the laser should be clearly visible.

[Gyro]

Definitely replace that 33uF first though, before touching the laser current adjustment - it has a direct influence on the stability of the current control loop.

It's rare to find one of those swing arm Phillips Lasers defective (maybe the odd CDM-0), unless they have been over-currented or suffered static damage - you need to put a short across the end of the flexi-print (paperclip) if you remove it. I don't know if it is being single beam rather than the later 3-beam, or because they were strictly designed around / in tandem with the Red Book spec, but they will generally read CDs that are too degraded for other pickups. They still don't pass the famous jam test though!