Vintage CD player repair : Sony CDP-C305 5 disc carousel

[Vince]

Hello,

After fixing a couple CD players recently for my old man, my first ones, I think I got the virus... I am starting to like fixing these things, can even feel the urge to buy half the old dirt cheap broken CD players I find for sale.... not good...


First one was an old Philips swing arm 6 disc cassette changer. Next was a modern (year 2000) junk all in one compact stereo system. Fixed the built-in 3 disc carousel changer in it. Was a pain, horrible design to work on, brrr...

Old man said he wanted a changer to put with his Cambridge stand alone amp he was given. So, I bought a few, half a dozen old broken CD changers last monday, because there was a discount on shipping up to that day. 2 Euros flat rate for shipping. So I searched for all the decent looking broken dirt cheap vintage CD changers... bought 6 of them.

Then I asked the old man if he preferred a 5 disc carousel of a 6 disc cassette, or a 100 CD juke box.... to which he replied :

- " Changed my mind I don't want a big changer any more, 2 or 3 discs is enough. I also do'nt want an old player, I prefer a sophisticated top quality modern expensive unit ".

Didn't know there was such a thing as modern top quality sophisticated Audio CD player... this sentence seems to contradict itself  eh ?
Or is there really top quality audio Cd players in 2021 ? Did some manufacturers decided to go that route ? Are they really that much better than the old 80's/ early '90's Philips transports and DACs ?  Can a human hear even hear the difference ? Hmmm....


Anyway, OK, thanks dad, so now what do I do with my players ?! Grrr...
"luckily" half of them I won't even get, because the sellers said they refused to bother shipping them given the very low price of the player (I will be refunded eventually)... even though the website stated they would ship. Apparently the "will ship" icon shows up on people's ads regardless of their consent ! Not cool.
So I think I will in the end receive 3 changers in all, if I get the count right.

The first one I already received today ! Seller was extremely quick to send it and transporter unusually lightning quick as well, quite baffled.

So here it is !    Cost only 3 Euros, plus the discounted shipping at 2 Euros, so  5 Euros delivered, I am broke now 

Let's fix it ! My third CD player repair.. let's see if I learned from my first 2 repairs... how long will it take me to diagnose and fix that one...

So, it's a Sony model CDP C305.   It's a 5 disc carousel changer, marketed in 1990 it seems, from what I can find.

Even though it weighs bugger all, it doesn't feel flimsy at all, quite sturdy, and the carousel mechanism sounds "refined", and quiet. Nice VFD display on the right side. Overall I quite like it.

Popped the hood. First thing that got my attention was the transport : it is tilted downward, it's hinged. Usually it would be mounted horizontally and be lifted up, to clamp the disc... but here looks like it's hinged and rotates. Quite original I found ?

Symptoms : sellers said that it won't reads discs.

After a quick test, I found :

- The drawer won't open or close when I press the button on the front panel. I can't hear any motor / mechanical noise either, so presumably it's an electrical problem, either motor is dead, or its driver.

- If  I place a CD on the carousel anyway, the player will do what it usually does : rotate the carousel 5 times, trying to read the discs. It fails to read the disc I put in it, so it just goes to the next slot and so on. Just like my previous CD player repair.  Then of course one it has checked all 5 slots, it displays "No disc" on the VFD.

So that's what I have got !

I don't see it trying to spin the disc at all, not even a little bit. Also, I can't see the laser turning on. I do however see the lens moving up and down once, full span, it's blatant.
It it needs a need pick-up, then luckily it's still available and is cheap as often. 10 dollars shipped from china on Ebay, but of course as always... 1 to 3 months for shipping !    Could not find any ad in Europe for fast shipping sadly. So no choice but wait for months 

The pick-up is easy to identify.. the label on it is readily visible as soon as you open the hood. It's a KSS 240A. Apparently also used on " Denon " Branded players, if I believe the ads on Ebay.


OK so let's try to fix this thing ! 

Luckily there is a nice, well done 23 page service manual for it :

https://elektrotanya.com/sony_cdp-c35_cdp-c201_cdp-c205_cdp-c305.pdf/download.html


So I guess first thing to do is remove the platter / drawer to get access to the transport and electronics underneath, so I can start checking things out...

[Vince]

Oh, just noticed something obvious too : the transport fails to lift up / clamp the disc ! 

Hmmm... fails to lift, fails to spin the spindle motor, fails to turn on the laser... too many thing wrong at once, suspicious !

So with some luck all these things work just fine and it's a higher-level problem, like a power supply issue or a dodgy cable or connector or something....

[mzacharias]

There was a lot of bad flat flex pickup cables on all the Sony models that used the KSS-240/A pickups.

Many perfectly good pickups replaced for no reason. The cable may be available generically somewhere but Sony has discontinued them long ago.

Bastards.

[Vince]

Thanks for the info !  Indeed this cable must be a very well known weak point because there quite a few ads on Ebay selling just that !

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=KSS+240A++cable&_sacat=0&LH_TitleDesc=0&_sop=15&_osacat=0&_odkw=KSS+240A+cable

At least I know I can get it then, if need be.

[Vince]

Started by investigating the mechanical side of things. The tray was stuck shut, would not budge at all, so I tried to fix that first.
Popped the underside plate and the front panel. Removed every screw I could find that seems vaguely related to the tray mechanism.... when I removed some bracket on the right side of the tray, which I later understood was there to guide the that side of the tray.. tray "popped" loose / free ! 

That revealed the stuff underneath... the transport in full glory, and a weird looking huge gear... service manual refers to it as the "loading gear".
Pulled that as well... once I had done that, it appeared it was more than just a big gear driving the tray... it has a dual purpose in life.
It also drives the transport up and down ! Quite clever.

It then all started to make sense... the tray was not in " sync " with the loading gear anymore, causing havoc.

After disassembling and reassembling the loading gear and tray like 30 times, eventually I got a good understanding of how it all went together, and got it operate properly, turning the loading gear by hand from underneath.

Transport would now go up no problem.


Then powered it up, hoping to have made at least some progress. What I did not anticipate was that I did more than doing some progress.... the above actually fixed it for good ! It's worked just fine first time !!!

 

It was only a mechanical problem, nothing more !

What I think happened is that someone must have pulled on the tray, it skipped a tooth or two on the loading gear, whole thing was now out of sync and caused misery. The transport would then try to come back up too soon, and would hit the tray from underneath, hence could not come its full up position, hence the micro switch detected that and of course did not even try to read a disc, which makes sense...

It all works just fine. No need to replace the pick or rubber belts or anything, incredible.
Appears to work fine, it's responsive when loading a disc, 2 or 3 seconds from scratch. Takes a second to skip from track to track. A tad slow compared to my old swing arm Philips, but still fine I guess. Cleaned the lens but no better.
Fast forward and rewind are very responsive. If I press PAUSE then PLAY again, it resumes playback instantly.
Audio never skips.

No it seems perfectly fine to me !

The VFD display looks gorgeous, love it. 30 year old, but still like new, super bright all over.

Midnight here so I will stop there. Tomorrow will check the eye pattern on the scope to check how strong it is. Service manual asks for 1.2Vpp +/- 0.3Vpp.


So, bought for 5 Euros delivered, fixed same day for zero Euro, can hardly get any better than this eh ?! 

[coromonadalix]

never had any flex cable  problems with the kss240 pickups,  the kss240 where at fault 90-95% of the time

The lens suspension gave up with time, the focus okay  could not be performed (disk presence not detected)

changed tons of kss240 and other kss xxx laser pickups, with drive belts

[Vince]

Thanks for the feedback.

I just checked the eye pattern on the scope. Not the most convenient thing in the world since the test points are located on a board that's part of the transport, and is half obfuscated by the bottom of the chassis... and the test points are precisely in the inaccessible part of the board (right by the pickup cable connector), ahem....
So I checked the schematics / followed traces, to see if I could tap the signals somewhere else, on the accessible part of the board.... yes I could. So I soldered a couple wires on the test points, this way I could flip the player to put it on it's feet, and use it normally (did want to risk using the thing while upside down...).  Then I could use scope the eyte pattern hand free, and use the player as much as I wanted to while observing the eye pattern on the scope.

Result below.

Amplitude of the signal, is about 1.05Vpp.   Service manual states that nominal value is 1.2V, +/- 0.3V.     So ranging from 0.9V up to 1.5V.

At 1.05V I am clearly low, though still within spec and players works fine with my 25/30 year old CDs....

So what should I do ? What's the practice in the business ? Should I increase the laser output to get as close to 1.5V as possible ? Should I adjust it for nominal 1.2V rather ?  Or should I just leave it alone since it works fine... me thinking that increasing laser output might be counter productive, as it might wear it out faster, and reduce even more what life is left in the thing ?

So maybe just leave it alone, and if / when it starts skipping/ acting up, check the eye pattern again and increase laser output but only juuust enough to make it work again ?

If you do think I should adjust it to whatever level, do you know which pots I should tweak ? I mean, the tiny PCB mounted on the pickup, holds 3 tiny trim pots. I don't know which one pertains to the laser, nor in which direction to turn it...
Adjusting it looks like it will be a pain since it's mounted on the pickup itself, so I can adjust it in real time, as a CD is playing. Would need to make an adjustment blindly, then play a CD to check the eye pattern, then stop playing, remove disc, to get better access to the pickup, adjust again, etc.. tedious and time consuming... but I see no other way 

Oh, forgot to say.... it happens once in a million time, but the player actually STILL had its remote... usually they are long lost. Plus, it works just fine, the keypad isn't even worn out, all keys are 100% responsive, no bad contacts.  Remote is cool as it allows you to switch randomly to any of the 5 CD slots (dedicated buttons for each of the 5 discs) which you can not do from the front panel.

I also saw in the schematics that this player uses the same DAC as my swing arm Philips, a TDA1543A... though in this Sony players, the DAC is preceded by chip labeled "Digital Filter ", so I don't know it's meant to alter the  audible spectrum / sound rendering, or if its purpose is of another nature ?§ Haven't checked the SM thoroughly to figure it out...

Anyway, I am starting to like this player...

[Gyro]

I would be tempted not to try to boost the the output of a 30 year old laser by adjusting a 30 year old pot (if you can find the right pot and direction).

If you want to know how much 'headroom' it has left, try playing a CDR. If it plays that ok then I wouldn't touch anything.


P.S. Nice fix.

[Vince]

Thanks Gyro. So that's one vote for " leave it alone" ! 

Just checked the inter web, no shortage of info on that pick-up ! Took only a few seconds to find the image below, indicating  what pot does what on the pickup.  Left pot is EF balance, whatever that is, middle one is Focus bias (which means "don't touch me") and the laser adjustment is the one on the right.

If I were to adjust it, I figured it might not be that bad of a job if... if I remove the carousel. This would leave me with just the bare tray, but the opening in it is very large and gives good access to the pickup pots, as can be seen in my pictures posted earlier.

Now just need to finish it up with a good cleaning of the front panel and remote control...

I have two more players in the pipeline, one is already en route, the other shall soon be. Can't wait... third player repair and I am already addicted, it's so much fun to be able to revive these things ! The feeling when you have it fixed, and nice music coming out of it as the disc is spinning silently and is half hypnotizing me as I can't help but stare at it endlessly as I am listening to the music... it's weird, irrational...but it's addictive... I want more of it ! 

[Vince]

Could not help... I played with the laser trimmer. Very cautiously of course... don't want to burn the thing.

Didn't even remove the carousel in the end. I simply grabbed the loading gear driving gear by feel from underneath the chassis, so I could turn it a bit. This way I could lower or raise the transport at will, to free the CD to access the trim pot on the pickup. Then I just rotate the carousel a little bit by hand to get it to the next slot (I just leave the CD in place in its slot, I don't even even bother removing it, no need), so that the aperture in the carousel lines up with the one in the tray, in the optimum way as far as getting the screw driver on the trim pot is concerned. It's still at a bad angle, 30° or so, but removing the carousel would not make it any better so... why remove it.
Bad angle but no choice, but it's good enough for what we have to do  so...

It doesn't take all that long, a couple minute top for one trial.

Anyway, result :

- Turned it a 1/16 tops, CCW. Made the laser output increase not decrease... kinda counter-intuitive... I guess the Japanese think differently...
That made the eye pattern amplitude jump from the original 1.05V , to 1.2V. Spot on the nominal value. Great I though... no, not so much ! the eye diagram looked funky, unstable, not as clean and "text book like" as it was before....  plus I could hear blatantly, a weird crackling noise on top of the regular audio track. Not good !  So move the trim pot the other direction. That got the signal down to 0.79V ... so 110mV below minimum spec. Still, player was working just fine !  Well....

So if it works fine below spec, at only 0.79V ... sure enough if I put it back at 1.05 where it was at the start, I would have quite a margin.

So that's it, in the end I just set it back to where it was from the beginning, no change... and I buttoned it up.

So, in this case, somehow, increasing the amplitude was detrimental, even though it was at nominal value, go figure.


So that one is done I think !

Now waiting for the two other players to show up.... in the mean time I have just been given an old super mega large flat screen TV.  Super large but weighs bugger all... super old only a guess, based on the fact it's got a VGA  input, and even SCART / Peritel.

[gOlek]

Hi Vince and all
I have bought this very player in a thrift shop for $5, with remote!
When it works it is great.
But
It doesn’t always work, I have to switch on/off several times before making it work.
Not working means:
-tray not opening (but some noise)
-with discs inside, none plays (carrousel turns, display shows playing icon but nothing happens)
Working means all functions work flawlessly.
Obvious solution: keep it on permanently (not always convenient)
Or maybe there is a cause that you may be aware of amd share with me.
I have some experience opening and doing basic repairs on electronics so I’m not afraid of going for it, eventually.
Thanks a lot

[gOlek]

Ohh well
Actually at the end of each disk, carrousel loads next but can’t play. Switch off and back on does make it play. it.

[Vince]

Hi there,

I don't know sorry, but if you do like I did and create a topic for it in the repair section, and post the link here so I know where to look. WIll try to help if I can 

Remove the lid / cover and maybe make a little video clip showing the problem, and upload it to youtube.

I assume of course that you have already downloaded the service manual for that player, if not well go do that immediately...

I am not sure I 100% understand the symptoms (hence video would help) but seems like the player basically "can" work fine, when it wants to... so that means there is nothing seriously wrong with it, from an electronics perspective... the transport works, the laser is not tired etc... the transport itself works, which is the most important.
So it's probably just a mechanical problem like was on mine, or some sensor/micro-switch issue.

Again without a video to really see/understand what's going on, hard to give advice...

So pop the cover and observe in detail what the player is doing.


See you in your thread...