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Electronics => Repair => Topic started by: Vince on March 25, 2021, 09:44:53 pm

Title: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 25, 2021, 09:44:53 pm
Hello world,

Getting carried away fixing old CD players, I am officially addicted. Bought a dozen of them in the past two weeks, progressively being receied... Got half of them by now. Not going to spam the forum with each and everyone of them, as there are many boring ones : have already FOUR of them diagnosed in 15 minutes tops... mechanical failures not electrical. Always... plastic gears here and there, with damaged teeth, causing either troubles with the opening of the tray, or the  radial motion of the pick-up, causing read problems.
So I am thinking about getting a small 3D printer some day, so I can hopefully make my own gears to fix all these players, and all those that will come after them, no doubt. Broken gears seems to be occurring so often that its worth investing some time getting up to speed with basic CAD modeling and 3D printing.

Anyway, today I am posting about this Sony CDP-291 as it looks interesting, first time I encounter this issue, and no quick diagnosis on this one, and for a change it's an electrical issue, so it needs some troubleshooting....

Inside it looks remarkably.... empty ! No mai board to fill the chassis !  The transport is plugged directly to the front panel / CPU board, and then a tiny, bare bone powers supply board, and that's it !  :o

Power board has zero filtering, as simple as it gets, 10 year old style : mains goes straight to the primary of the transformer. Zero protection, zero filtering, not even a fuse, nothing. Secondary is alike : discrete diodes for rectification, filter caps, that's it.


Issues :  power looks fine, CPU board too : display comes up, buttons do things, it reacts, and I can open and close the tray. Problem seems to be in the CD transport part, linked to the front panel via a single wide ribbon cable.

I see a couple obvious problems...

1) When you power it up, the pickup is moved to the center of the disc, as usual. However once it has gotten there, it doesn't stop ! The motor keeps pushing the pickup endlessly, as if it thought i didn't reach the end. So the pickupy is litterally banging its head against the transport, indefinitely ! Only way to stop it is to power off the player.

2) The spindle motor seems out of control : it can stop and start as ti should, when the tray is open or closed. However when it spins, there doesn't appear to be any regulation of rotation speed : it just spins full blast, screams like a jet engine ! .. but in the video clip made below you can't even hear it because the pickup makes such a loud and scary noise !


Work done so far : for the pickup problem, I though it would be easy. I mean there is a microswitch that detects precisely thatthe pickup has reached the center of the disc... so I thought well, switch must be bad. So I checked it and.... it works just fine : closes right when the pickup reaches the center of the disc, well a couple mm before actually. Then as soon as retract the pickup a couple mm, switch opens. Did it 10 times in a row, never fails...  So no easy fix for Vince, hence I am here... more troubleshooting needs to be done....

The fact that there is also problem with the spindle motor, two weird problems at once, means I guess that they must have a common cause, and most likely located on the transport PCB itself, locally, rather than in the CPU/front panel board ?

There are a couple chips on the transport PCB. I guess the bigger one is the logic stuff and the smaller chip might be the driver chip for the servo and motors....

If the logic chip is fried I am cooked... and it's more likely that the driver IC, if indeed that's that, is faulty. So I think I will start my investigation around the servo/motor driver IC...

Vidéo clip :

https://www.youtube.com/watch?v=vlB0-S5bTlE (https://www.youtube.com/watch?v=vlB0-S5bTlE)
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Mike P on March 25, 2021, 10:05:33 pm
I expect there to be a contact switch which tells the player when the laser head has reached the end of its travel. I'd start by checking the function of this switch and if necessary cleaning it.

A turntable motor going crazy speed is usually as sign that the clock signal has been lost.
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 25, 2021, 10:18:10 pm
I expect there to be a contact switch which tells the player when the laser head has reached the end of its travel. I'd start by checking the function of this switch and if necessary cleaning it.

Yep, as I explained, it's the very first thing I checked !  ;)   Switch appears to be working just fine.


Quote
A turntable motor going crazy speed is usually as sign that the clock signal has been lost.

Thanks, noted...

Found the service manual. Nice block diagram and schematic in there, attached below.

Past 23h here, going to bed...
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: tautech on March 26, 2021, 07:02:04 am
About replacement plastic/nylon gears....you might find something that will work for the other units in the repair queue here:
https://nz.rs-online.com/web/c/pneumatics-hydraulics-power-transmission/power-transmission-gears/spur-gears/?sort-by=Material&sort-order=asc&applied-dimensions=4294612520
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Gyro on March 26, 2021, 10:39:10 am
Time to look at pin 10 and 11 input of IC102 (the driver chip for all the coils and motors). That should tell you whether the problem is a damaged driver chip or the problem is further back in the chain. If it is not responding to the limit switch, my bets would be on IC102 though.

It's sad to see how far Sony had sunk by the time of that player. There will be a thermal fuse inside the transformer by the way. They are pushing the strict limits of Class II insulation though - the inner brown and blue cores of the mains cable should have another layer of insulation (heatshrink) on them where they go into the connector for instance, and the mains lead isn't restrained from contact with secondary side parts if it isn't plugged into the rear PCB properly. I can't see anything constraining the spacing between that end of the PCB and the chassis either. Naughty.


Go and find yourself a nice example of a Philips CDM2/4 single disc swing-arm player (preferably with brushless spindle motor) and TDA1541. Tweak it, and enjoy the music.  ;)
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 26, 2021, 06:37:25 pm
@Tautech : thanks,; will have a look see what I can find, you never know your luck I guess !  ;D

Time to look at pin 10 and 11 input of IC102 (the driver chip for all the coils and motors). That should tell you whether the problem is a damaged driver chip or the problem is further back in the chain. If it is not responding to the limit switch, my bets would be on IC102 though.

Yes this driver chip is my main suspect for now for sure ! I will be probing around heavily in this area....
However I am sad because if it turns out to be this chip, which is likely, then the repair will not be economically viable... just looked on Google, this chip is obsolete, not sold by the usual mainstream retailers. So, has to come from ebay, hence a bit risky but mostly... too expensive. 17.5 Euros for one single chip, wow.... 15/20 Euros is precisely what I usually pay for the stack of players I have just bought (still coming in, got 4 more today !! ), including shipping.  So replacing that ship will double my investment.. sure the drive will work and be worth.... maybe 30 Euros if I am very lucky. More like 20 or 25 tops. So I will be losing money... If I just don't fix it and  call quit right now, I will limit the loss to what I have already paid for it.

That being said... I can't help but want to buy that chip anyway, just so I can see if the diagnosis was correct or not, and for the joy of seeing the player singing again...

Can't afford to that with my entire pile of defective players though, or I will go bankrupt !  :-DD

OK so let's probe around that chip to see what's what...

Quote
It's sad to see how far Sony had sunk by the time of that player.]It's sad to see how far Sony had sunk by the time of that player.

What I don't understand is that it's not even that recent ! I mean, I could understand that by the mid to late '90s, cost cutting was starting to take its toll on on al manufacturers... but this player is form 1990 ! CD players were still fairly new by then. Just the year before, were the '80's !

Quote
Go and find yourself a nice example of a Philips CDM2/4 single disc swing-arm player (preferably with brushless spindle motor) and TDA1541. Tweak it, and enjoy the music.  ;)

I thought my CDC 486 swing arm was old, but apparently not old enough..... uses a CDM4 and TDA1543 not 41... so I guess I need to find reallllly old Philips players, from the 80's.. as 1990 doesn't cut it apparently.

Google just found me this site :

https://www.hifi-advice.com/blog/classics/digital-classics/philips-cd-player-dac-chipset-and-transport-list/ (https://www.hifi-advice.com/blog/classics/digital-classics/philips-cd-player-dac-chipset-and-transport-list/)

gives a ton of info about the various Philips mechanisms, and a time line of models.

I have bought a dozen or more of random old players now... to gain experience fixing them. Need to calm down or I will lose my shirt... and won't know what to do with all these machines ! I mean I have only one set of ears...

There are countless brands and models, I need to focus on something specific or I will quickly fill my yet to be constructed garage, with dozens of random players...

So yeah, I guess it's time to start focusing, and actively look for old Philips from the '80s with the TDA1541 (there are variants I gather...), swing arm and hopefully a cool looking one that's cast meal, they look so sexy...  8)

Don't know how to figure out what CD player models had brushless motors though ? The site above gives info about DAC and mechanisms / transports... but is there a table somewhere listing all the models that use brushless motors ??

Anyway, I had a quick look at Ebay, and the really old Philips players cost a real fortune, 100/150 up to easily 250 or even 500 Euros !  :o
Not my world... but ebay is for professionnal speculators these days, sellers are trying to surf the audio wave so to speak, and extract as much money as they can from innocent audiophiles... not my cup of tea. I don't like speculators... so I will steer clear from ebay, and rather keep an eye on the local ads, as it's where the average joe goes to flog whatever he has to flog. Most of the time it's filled with prohibitively priced broken untested random pieces of junk, but every now and then you do come across nice stuff at a reasonable price, or even dirt cheap when the guy simply doesn't know what he is looking at, and just wants a quick buck.
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Gyro on March 26, 2021, 07:14:56 pm
Yes, consumer CD players got cheapened quite quickly - some brands quicker than others I guess.

I was going to suggest maybe replacing that section of the chip with an opamp and push-pull transistor follower, but the chip block diagram is simplified so it would take some luck to get the system stable (sled motor keeping track with the voice-coil lens movement) probably too much trouble and also assumes that the other driver outputs are ok. Pins 10 and 11 should give you the answer anyway.

Ha, I was going to point you at that transports / dacs list!

The CDM2/10 and CDM4/11 were the main brushless transports of that era (the CDM4/19 being the much more common brushed motor one). The TDA1543 was originally designed as a low pin count cheaper dac replacement for the TDA1541(A), to be used for portable applications, but they found its quality good enough to put in lower end CD players too. It was the last of the Philips multi-bit dacs before they switched to Bitstream (sigma delta).  CDM4/11 + TDA1541A is a nice combination.

You have to be patient on ebay, bide your time for a decent low bid one rather than buy-now. Leave the cast metal ones (CDM1 Mk2 for instance) to the 'enthusiasts'. There's nothing wrong with the more mass market composite material ones I mentioned above. I think you have enough repair experience now to be a bit more selective.  :)

P.S. The really old expensive ones are really priced as collectors items - too early for reliability and typically only 14 bit (TDA1540) dacs.

P.P.S. Here's another, more comprehensive list (and useful site). Don't ignore Marantz, Rotel etc.  https://www.dutchaudioclassics.nl/the_complete_d_a_dac_converter_list/ (https://www.dutchaudioclassics.nl/the_complete_d_a_dac_converter_list/)
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: shakalnokturn on March 26, 2021, 10:50:37 pm
Once more I have to agree with Gyro.

Have you checked that power is clean?
Considering main power filtering is quite far away from the transport and some highish current variations must be involved I'd definitely check on any electrolytics on the hidden side of the transport PCB.
Next check would be oscillator.

This is not a player to hold on to...

Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: mzacharias on March 27, 2021, 12:48:06 pm
I would still check other power supply stuff first, like for example a -5V source, but I would keep in mind that the decoder IC, (CXD-2500Q on some models for example) controls what the motor driver IC does.

In normal operation there is a certain duty cycle. Once the motor is moving the duty cycle drops to maybe 50% or so. In your case it's possible the IC is railing out with a near 100% (DC) output all the time. That is where I would go next after the power supplies.

Just a thought... but Sony had a lot of bad decoder IC's back then.
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: tooki on March 27, 2021, 01:47:42 pm

It's sad to see how far Sony had sunk by the time of that player. There will be a thermal fuse inside the transformer by the way. They are pushing the strict limits of Class II insulation though - the inner brown and blue cores of the mains cable should have another layer of insulation (heatshrink) on them where they go into the connector for instance, and the mains lead isn't restrained from contact with secondary side parts if it isn't plugged into the rear PCB properly. I can't see anything constraining the spacing between that end of the PCB and the chassis either. Naughty.
It’s an entry level model, you can’t expect luxury construction. Higher end models of the day (and much later) have more robust construction.

Correct me if I’m wrong, but I think the rules on insulation weren’t nearly as strict back then (we are talking 30+ years ago!). In 80s era equipment it wasn’t rare to see completely exposed AC terminals inside a device.

That internal plug won’t really be able to contact anything if not plugged in. It’s a female plug, so the contacts are inside the housing.

And yes, there is something to separate the PSU PCB and chassis: barely visible in the photo, there’s a white nylon standoff below the board, directly under the AC connector.
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Gyro on March 27, 2021, 04:35:59 pm
Correct me if I’m wrong, but I think the rules on insulation weren’t nearly as strict back then (we are talking 30+ years ago!). In 80s era equipment it wasn’t rare to see completely exposed AC terminals inside a device.

That internal plug won’t really be able to contact anything if not plugged in. It’s a female plug, so the contacts are inside the housing.

And yes, there is something to separate the PSU PCB and chassis: barely visible in the photo, there’s a white nylon standoff below the board, directly under the AC connector.

Hmm I'm not sure, that unit is about 8 - 10 years before I got into designing metal cased Class II volume consumer stuff. It wouldn't have passed by then because you have the (albeit remote) possibility of a single insulated conductor coming into contact with a chassis burr or sticking up bit of secondary side stuff. Ironically the connector wouldn't be treated as much of an issue because it's rigid insulation and recessed contacts (and approvals) - although the mains cable should still be short enough to prevent it from accidentally reaching any part of the secondary side), but inner cores without supplementary insulation would have been a fail. I never really never thought too deeply about it at the time, mains leads automatically came from the supplier with heatshrink fitted, we carried on using the same ones as existing products.

Ah, yes - I see the standoff now, I'll let them off that one then.  :)
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 27, 2021, 08:27:31 pm
I was going to suggest maybe replacing that section of the chip with an opamp and push-pull transistor follower, but the chip block diagram is simplified so it would take some luck to get the system stable (sled motor keeping track with the voice-coil lens movement) probably too much trouble

Yep, definitely way too much trouble ! As Shakalnokturn said, it's a super crappy low end unit, just some player bought randomly, no sentimental connection to it or anything so... the aim is not to fix it at all cost (labour or money wise). The aim is merely to diagnose it, to gain a bit more troubleshooting experience. Once it's diagnosed, job done, don't need that player any more...

Quote
and also assumes that the other driver outputs are ok. Pins 10 and 11 should give you the answer anyway.]and also assumes that the other driver outputs are ok. Pins 10 and 11 should give you the answer anyway.

The block diagram is so confusing to me.. not used to this kind of drivers. The datasheet is only 3 pages long and doesn't teach me much more than the schematics in the service manual....
Reminds me though of the Philips driver chip that I found in the 3 disc carousel crappy stereo system I fixed a few months back, my second repair. The datasheet for that chip was very informative. Had two drivers with differential inputs and differential outputs.

The LA6532M in that Sony player looks like it has 4 drivers, two with diff inputs and outputs for the Sled and Spindle motors, and two single ended drivers for the Tracking and Focus servos on the pickup.
You say pins 10 and 12, so looks like the two diff inputs for the Sled motor... from what I understand, the 2.5V volts indicated on the schematics correspond to the "idle" state, ie the logic chip/ decoded is not asking for any motor movement. So if I get 2.5V on both inputs while the Sled motor is turning, then it means the driver IC is not doing what it is being asked to do, hence defective... OK will check for that !




Quote
The CDM2/10 and CDM4/11 were the main brushless transports of that era (the CDM4/19 being the much more common brushed motor one). The TDA1543 was originally designed as a low pin count cheaper dac replacement for the TDA1541(A), to be used for portable applications, but they found its quality good enough to put in lower end CD players too. It was the last of the Philips multi-bit dacs before they switched to Bitstream (sigma delta).  CDM4/11 + TDA1541A is a nice combination.

P.S. The really old expensive ones are really priced as collectors items - too early for reliability and typically only 14 bit (TDA1540) dacs.

P.P.S. Here's another, more comprehensive list (and useful site). Don't ignore Marantz, Rotel etc.  https://www.dutchaudioclassics.nl/the_complete_d_a_dac_converter_list/]The CDM2/10 and CDM4/11 were the main brushless transports of that era (the CDM4/19 being the much more common brushed motor one). The TDA1543 was originally designed as a low pin count cheaper dac replacement for the TDA1541(A), to be used for portable applications, but they found its quality good enough to put in lower end CD players too. It was the last of the Philips multi-bit dacs before they switched to Bitstream (sigma delta).  CDM4/11 + TDA1541A is a nice combination.

P.S. The really old expensive ones are really priced as collectors items - too early for reliability and typically only 14 bit (TDA1540) dacs.

P.P.S. Here's another, more comprehensive list (and useful site). Don't ignore Marantz, Rotel etc.  [url=https://www.dutchaudioclassics.nl/the_complete_d_a_dac_converter_list/]https://www.dutchaudioclassics.nl/the_complete_d_a_dac_converter_list/ (https://www.dutchaudioclassics.nl/the_complete_d_a_dac_converter_list/)


Thanks for all the good info, concise and practical...
Glad to hear that the mega expensive ones are not the ones I should be seeking ! LOL The one I saw for 400 Euros on Ebay yesterday, a CD880, is now at 631 Euros and still counting !  :o 

https://www.ebay.fr/itm/Philips-CD-880-CD-Player/184720561239?hash=item2b02341457:g:ojIAAOSwqP9gVxlu (https://www.ebay.fr/itm/Philips-CD-880-CD-Player/184720561239?hash=item2b02341457:g:ojIAAOSwqP9gVxlu)

So if I understand... CD was created in 1982, first generation of Philips ridiculously expensive yet not technically the best, using TDA 1540.
Then in 1990 players already started to go downhill, with the TD1 1543 that's good but not  exceptional.
So basically that means that target is quite narrow, 5 years or so : before 1990 but after the early 80's... so the late '80s with TDA 1541, and that's about it, roughly speaking. Simple enough for me to remember, I like that !

Marantz : yeah, I hav gathered by now that basically they often liked to use Philips transports and DAC. So you could get the Philips goodness but in a different "package", different look. Same cake different icing  so to speak ! Something for everyone....

Quote
CDM4/11 + TDA1541A is a nice combination.

You won't believe it ! Certainly won't overlook Marantz, but one shall not overlook lesser models too !
I mean, today I received yet another CD player, a small tiny unit, very compact, low end looking, branded " Radiola"... don't laugh.
I bought it thinking it's a piece of junk but it's not a very common unit, kinda exotic by now, and I just liked the looks of it, somehow I found it cute. 10 Euros only and of course defective, so I could have some fun repairing it. Display doesn't come to life (but player is responsive if you push the buttons), and it fails to reads discs. Does load them just fine and spins them for a couple seconds... but then stops.
Anyway, point is, I took it apart to have a closer look, and to my shock but not horror at all... this shitty looking player comes with a swing arm ?!  :o  ... closer look... a CDM4/11 in white, and TDA 1541A , yes, just what you suggested to me !   In that humble looking player !  :-//
And since it all adds up : it was made in the late '80's indeed : date codes on the various ICs suggest last month of 1987.

So now I just don't find it "cute" anymore, I also find it very valuable ! Will definitely try to fix it and hang on to it !  :-+

Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 27, 2021, 08:47:58 pm
Have you checked that power is clean?

Yep. I mean, checked the outputs of the power board. Has two DC outputs and an AC output (4Vac).

DC outputs are labeled +8V and -40V.   Unloaded (connectors disconnected from the power board), 8V reads 11,36V but once loaded it's pretty much spot on 8V.  Measured 7,96V. Ripple is a bit high I will admit, at 45mV measured with my non-RMS DMM. If I looked with a scope I guess I would find 100mVpp or something, which is way too much yes, even for digital stuff...
From memory, all my old 2000 series Tek scopes from the '80s with TTL chips allowed to 20mV or so for the digital stuff, and less than 10mV for the sensitive analog stuff.

The negative 40V output, I measured unloaded at -53,7Volts and once loaded, at -41,2V + 0,84V ripple (again with my averaging DMM).

I assume the main board, well there are none, I mean the front panel board that is, must have some local voltage regulator. Well ye sit does, just looked... looks like a small 5V switch-mode regulator. Local rails are + and - 5V mostly. Will have a closer look at the schematic and take the front panel board out of the fascia so I can see what's what and probe all the local power rails for accuracy and ripple, this time using the scope. Will check all the electrolytic caps... will buy one of those cheap ESR meters... I will not allow myself to buy any more CD players until I have gotten myself an ESR meter...  :-[


Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 27, 2021, 08:50:25 pm
Just a thought... but Sony had a lot of bad decoder IC's back then.

Oops, good to know, a bit scary... these aren't readily available off the shelf I supposed, and not dirt cheap either... let's hope it's not that : If it is... scrappy it will be !  :-//
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Gyro on March 27, 2021, 09:44:39 pm
Quote
CDM4/11 + TDA1541A is a nice combination.

You won't believe it ! Certainly won't overlook Marantz, but one shall not overlook lesser models too !
I mean, today I received yet another CD player, a small tiny unit, very compact, low end looking, branded " Radiola"... don't laugh.
I bought it thinking it's a piece of junk but it's not a very common unit, kinda exotic by now, and I just liked the looks of it, somehow I found it cute. 10 Euros only and of course defective, so I could have some fun repairing it. Display doesn't come to life (but player is responsive if you push the buttons), and it fails to reads discs. Does load them just fine and spins them for a couple seconds... but then stops.
Anyway, point is, I took it apart to have a closer look, and to my shock but not horror at all... this shitty looking player comes with a swing arm ?!  :o  ... closer look... a CDM4/11 in white, and TDA 1541A , yes, just what you suggested to me !   In that humble looking player !  :-//
And since it all adds up : it was made in the late '80's indeed : date codes on the various ICs suggest last month of 1987.

So now I just don't find it "cute" anymore, I also find it very valuable ! Will definitely try to fix it and hang on to it !  :-+


Yay, you found yourself a genuine Philips CD371 by another name! Check the ebay prices.  :clap:

Now that's the one to concentrate on, forget about the Sony!

The service manual is here... https://elektrotanya.com/philips_cd371_sm.pdf/download.html (https://elektrotanya.com/philips_cd371_sm.pdf/download.html)  It shares the same transport and PCB as the CD372 (CD371+ IR remote), 471 (same as 371 but larger case + VFD Display) and CD472 (CD471 + IR Remote).

I'm running a tweaked CD472 and am very happy with it. Note that the Micro (front right) has CD472 written on it. All models are the same capabilities with H/W mods. I have a CD371 too and find its size rather cute. The only weakness with the CD37x is that the LED display tends to be a bit unreliable (it has a built-in serial interface), not a big deal though because the serial format is very simple and you can get standalone chips.

I suggest starting another thread for this one.


P.S. Watch out for ESD on that transport ribbon when unplugged. A metal paperclip slipped over the end is the standard protection method.
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 28, 2021, 06:19:31 pm
Yay, you found yourself a genuine Philips CD371 by another name! Check the ebay prices.  :clap: 

Wow !!! Found 4 for sale on ebay Europe. Most reasonably priced is about 100 Euros ! Two sell for 130/150 shipped, and the last one is from a guy on crack who wants 400+++  Euros for it !  :o
Paid 10 Euros for mine !  :)

Jeez...

Quote
Now that's the one to concentrate on, forget about the Sony!

Will proved the driver chip a bit as you suggested earlier, then will tell the seller (who was curious to know what was wrong with it) that I need to replace that chip and it's no economically viable, sorry bob...


Quote
  It shares the same transport and PCB as the CD372 (CD371+ IR remote), 471 (same as 371 but larger case + VFD Display) and CD472 (CD471 + IR Remote).

Wow, you sure know your old Philips !  8)

Quote
The only weakness with the CD37x is that the LED display tends to be a bit unreliable (it has a built-in serial interface), not a big deal though because the serial format is very simple and you can get standalone chips.

Oh, thanks, problem already solved then. Just need to bodge the stand alone chip somewhere on the front panel. I hope the chip is not 50 Euros... or I would have to replace it with a tiny 8 bit micro to emulate it. I guess the Philips nerds have already sniffed the protocol and documented it.

Quote
I suggest starting another thread for this one.

Yep sure, of course, it deserve a public repair ! I am already very proud of my little Radiola !  ;D

Quote
P.S. Watch out for ESD on that transport ribbon when unplugged. A metal paperclip slipped over the end is the standard protection method.

Simple and clever.. paper clip, will buy some soon then ! 8)



Some more : along with that Radiola, same day I also received another of these "doesn't look like much but it's different than the rest of the crowd and dirt cheap so will buy it anyway, to diversify my experience" .... I got a Toshiba XR-9128.  When I opened it, guess what ? Same internals as the Radiola ! Same CDM 4/11 cast resin though this time black not white, and same TDA1541A !  The main board looks 99% identical. Only a wee wider maybe, and the routing of the components, CPU and DAC, in the lower right corner of the board, is a bit different. But other than that.... Clearly one board is merely a slight variation of the other. Date codes on the DAC is very early 1989. Cabinet, like the main board, is also a tad wider. Has IR  remote sensor too, and a VFD display not LED. That fits your description of the Philips CD 472 ?

Whatever the model, do you think it might indeed be yet another Philips under the skin ? Or like the Radiola, a plain simple rebadge, and even the front panel is identical to the Philips ?

Paid only 10 Euros for it, and it works just fine, I don't even need to do anything to it ! Detects the CD / TOC  in an eye blink, and switches from a track to the next at the speed of light. It's really in tip top shape !  :)  Only thing that would need doing I think, as preventative maintenance, is the rubber belt that operates the tray. Tray opens and closes just fine right now, but the belt looks like it's on its last leg. Very sloppy and with many deep cracks all over it. It won't last another 30 years for sure...

Since it works, I could use it to swap transport with the Radiola to help me narrow it down.


And, some more... still the same day (I received 4 players that day...), I also got another cheap unknown player that I somehow wanted to buy, because the brand name didn't ring any bell to me : "DIGITAL" is the only marking on it. So I though OK, let's see what is this thing.

When I finally had it on the bench... noticed that "DIGITAL" might not be the brand name after all... in the top left corner of the front panel, where you normally see a brand logon, there was nothing but some indentations in the plastic. Maybe the logo came off, was glued and the glue didn't stand the test time ? Don't know. Anywho, at the back of the cabinet there is an ID plate that says " Technics model SL-PJ25, Made in Japan".  Ah, a Technics then, not a " DIGITAL", silly me ! :-DD

I was eager to see the internals, as I have a couple Technics players that feature a swing arm, somehow. So would this one have one ?
.. NOPE.... is it a boring / conventional transport then ? NOPE either ! This thing surprised the hell out of me : it used something weird I have never seen before !!!  See pics below tell me what you think !

It looks like a mix, conceptually, of a swing arm and a linear tracking. The pickup does move linearly, in a straight line like a conventional transport, however the pick is not moved using a traditional DC motor with gears and such. No. Here the track is a beefy metal bar on which rides a big coil. When the coil is energized it moves along the track. Pickup is tied to the coil of course.
So it's like a swing arm, no gear, fast moving, and perfectly smooth and quiet. And see the pickup : it's in a nice cast metal housing !
This transport is so original and well built, a joy to look at see moving !
I like innovative engineering and build quality ! I am DEFINITELY keeping that one as well !
Doesn't work though, doesn't detect CD's, and it won't try to spin the disc.

Searched a bit, looks like they call this thing a "linear motor". Makes sense... first time I see one.


Pics of the Toshiba / Philips ? then pics of the Linear motor Technics in a separate message, to keep things tidy...

Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 28, 2021, 06:24:35 pm
Now pics of the Technics SL-PJ25 with the linear motor and cast metal pickup assembly.

Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Gyro on March 28, 2021, 07:22:04 pm
Wow, you've certainly developed a lot of luck!

That one isn't a CD472, but I've seen that layout, I'll look through my manuals collection. It's certainly a Philips designed and manufactured PCB. The front panel PCB may be very similar or identical to the CD472 though. Yes it is a VFD - if you compare the mains transformer with the one on the CD371, you can see the additional secondary windings for the VFD filament and supply. I feel a Frankenstein's monster coming on! This isn't that surprising - Philips were the masters of CD technology in those days (even though co-developed with Sony) and sold transports, board kits etc to other manufactures, big and small including some well know HiFi names (Cambridge Audio, Arcam, Quad and others). Rotel for instance, took the transports (brushed) and Phillips reference design and designed their own PCBs. It was quite interesting at the time to see Hi-Fi reviews of different manufacturers models with different externals but the same Phillips internals, often completely unmodified.

That Technics looks interesting too - a few Japanese manufacturers tried linear voice coil transports before everyone settled on the cheap motor and gears approach.


EDIT: Silly me, I though it looked familiar - It's a CD473. The strange placement of the TDA1541A (far from the opamps) is a giveaway. Also very few other players used the brushless CDM4/11 transport. Service manual:  https://elektrotanya.com/philips_cd473-00r-01r-05r-07r_sm.pdf/download.html (https://elektrotanya.com/philips_cd473-00r-01r-05r-07r_sm.pdf/download.html)

... Actually it's a CD473 depopulated - it doesn't have the track selection memory fitted. Unfortunately, the display chip on that on is I2C, not shift register on account of the number of display elements that it has to drive.

EDIT1: The Toshiba is actually closer to the Marantz CD65-DX regarding the display (both based on the CD473 main board but swap favourite track list for simultaneous Track and Time display on the front panel. I have the service manual if you need it.
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: shakalnokturn on March 28, 2021, 09:13:01 pm
Some nice catches indeed.

If you're out to fill your garage with CD players rather than T.E. because it's cheaper and you like the swing arm models you may find variations under Schneider and Grundig names too. (I didn't know about the Toshiba though.)

On the brushless motors I recommend disassembling, cleaning the old grease and re-greasing with the appropriate type.
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Gyro on March 30, 2021, 12:11:53 pm
I find that a single small drop of sewing machine oil is sufficient for the brushless motor bearings. The shaft runs in sintered bronze bearings and it is so large in diameter compared to the brushed ones that the wear must be negligible. The only real force acting on it is the vertical thrust from the disc clamp so having the end of the shaft running in a little pool of oil helps to prevent wear.


Going OT a bit (though I didn't start it  :D) to the Technics SL-PJ25. I found the service manual. In terms of transport and electronics, it's a very complex beast compared to the Philips ones. There are pots for adjusting eye patterns, PLL jitter waveforms etc that you simply don't have to worry about on the Philips. Given that the aim of both is simply to present the right bits to the DAC at the right time, they seem to have gone strangely overboard. Bits are bits after all. It does have the Technics MASH DAC though, which was well regarded at the time - I can't find the datasheets for the ICs though. I suspect that it is going to be something of a major project if it doesn't work!

The service manual is here... https://elektrotanya.com/technics_sl-pj25_cd_player_sm.pdf/download.html
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 30, 2021, 03:02:56 pm
Thanks for all the detailed info, you sure know your stuff ! ;D

So in short, it's technically a Philips, inside, so well worth keeping, but Toshiba made their own front panel and own VFD... so it's not a rebadged Philips like the Radiola was, it's a proper Toshiba finished product, but with Philips internals. So the Philips collectors/speculators will look down on it, so will be worth nothing compared to a CD473.. even though it's pretty much one. TO hell with the speculators, I will keep my 10 Euros Toshiba and enjoy it very much ! :-+

I downloaded the service manual for both the CD471 and the Marantz.  Hopefully I won't need them anytime soon, since the drive currently works perfectly..
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Gyro on March 30, 2021, 03:17:56 pm
Haha, let's say that the subject plays very nicely with my personal research and projects.  ;D

Yes, the Toshiba (and the Marantz CD65-DX) both used the CD473 main board, with favourite track memory and display removed, and their own front panel display board added. The Marantz was made by Philips anyway (it was one of their brand names) so it could be that the Toshiba uses the same front panel and display as the Marantz, therefore also made by Philips - I haven't been able to compare front panel photos well enough to confirm. This would be useful as I have the Marantz service manual, but can't find the Toshiba.

By the way, only 2 Toshiba models (the 9128 and9228 I think) used the CDM4/11, you struck lucky, so don't go buying up the rest of the range!  :scared:

As for the Technics, I wonder if they were trying to work around patents with their player, or just started from a blank paper with their designs, but the resulting implementation seems very different (not meaning bad, just more complex for the same job).


P.S. The IR remote uses standard Philips RC5 format, so any basic Philips CD remote or universal remote should work with it.
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 30, 2021, 03:34:54 pm
Haha, let's say that the subject plays very nicely with my personal research and projects.  ;D

My luck then ! 8)


Quote
Yes, the Toshiba (and the Marantz CD65-DX) both used the CD473 main board, with favourite track memory and display removed,

Just to ve clear... you mean, the "map" of track numbers that I see on some players ? A "grid " populated with track numbers ? There is a special chip, H/W required to implement this functionality, the main CPU can't be bothered ?
Looking at the pic I took of the main board of the Toshiba, I see only one unpopulated chip, a big 24pin DIP chip, at the very bottom right corner of the board, right by the right side of the DAC.. is that it ?


Quote
The Marantz was made by Philips anyway (it was one of their brand names)

Oh ! Didn't know that... was trying to figure out what country Marantz was from !  :-DD
So it's like my little Radiola then ! Old man visisted me last sunday, used to train service for white good for 30 years... he told me that Radiola, like Martanz then, was just one of several Philips brands. Even said that at some point, products even were marketed as a " Philips / Radiola ", with both names figuring on the same product !

Quote
so it could be that the Toshiba uses the same front panel and display as the Marantz, therefore also made by Philips - I haven't been able to compare front panel photos well enough to confirm. This would be useful as I have the Marantz service manual, but can't find the Toshiba.

Yeah that would be good to know indeed ! I can take close up pictures of the VFD if you like, to help figure it out. Google Image would probably be helpful too...


Quote
By the way, only 2 Toshiba models (the 9128 and9228 I think) used the CDM4/11, you struck lucky, so don't go buying up the rest of the range!  :scared:

Good to know indeed !  ;D
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 30, 2021, 03:46:01 pm
If you're out to fill your garage with CD players rather than T.E. because it's cheaper and you like the swing arm models you may find variations under Schneider and Grundig names too. (I didn't know about the Toshiba though.)

Good to know !  :)

HOWEVER, you bad mouth.... NO, buying CD players is NOT a substitute for TE ! GRRRR !!!   :box:

Actually I have just decided it's time to stop buying these things... I got the basics of CD players now... checked my bank account, 200 Euros overdraft... checked my home accounting S/W for CD players.... apparently I bought the first one 3 weeks ago, bough 16 of them so far, for a total amount, shipping included, of a bout 300 Euros !!!  :o  Wow, insane !  Had I not succumbed to these old players, I would be 100 positive not 200 negative, ARRRRGH !!

So..... time to get reasonable I think !

I will keep the 5 or 6 players that are actually interesting to me, will fix them as I go, posting here, and will try to get some of my money back by selling the 10 remaining players. Will try to fix them  so I can either get 5 or 10 Euros more for them, or at the least, stand a chance to sell them at all... because other than me, who would pay for a defective player, ahem...

What I find ironic is that in the end, the one I will keep are the very last one I bought, and players which I bought thinking they were random junk, whereas the first 10 players, from big names, which I thought were nice... are in fact either junk, or mundane at best.

I also now need to resume work on my house, enough time spent in the lab ! Had my fun for sure, but now time to finsh the dry walls in the toilet and bathroom, and hurry up with the construction of the garage !  Need to get the buildling permit for it, already got refused twice, need to modify it ! I can't do that if I spend my time and money fixing CD players !   :scared:

Quote
On the brushless motors I recommend disassembling, cleaning the old grease and re-greasing with the appropriate type.

Never done it. How hard and "risky" are they to take apart ? I would hate to ruin a nice swing arm....   :(
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: andy2000 on March 30, 2021, 04:17:27 pm
I would check that ribbon cable carefully.  I used to see a lot of them fail in Sony changers of that vintage.  It flexes every time the tray is opened or closed, so they can develop open conductors.  Check it for continuity since any breaks can be practically invisible. 
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 30, 2021, 05:16:38 pm
Going OT a bit (though I didn't start it  :D) to the Technics SL-PJ25. I found the service manual. In terms of transport and electronics, it's a very complex beast compared to the Philips ones. There are pots for adjusting eye patterns, PLL jitter waveforms etc that you simply don't have to worry about on the Philips. Given that the aim of both is simply to present the right bits to the DAC at the right time, they seem to have gone strangely overboard. Bits are bits after all. It does have the Technics MASH DAC though, which was well regarded at the time - I can't find the datasheets for the ICs though. I suspect that it is going to be something of a major project if it doesn't work!

The service manual is here... https://elektrotanya.com/technics_sl-pj25_cd_player_sm.pdf/download.html


Yep, there is a full row of orange trimmers right next to the track for the coil. Easy to spot on my pictures.
Yes I am sure it must be a lot of "fun" if one needs to fiddle with all of them to get the thing working to spec !  :o

Will do my best to fix it, we will see how it goes...
That said if I fail to fix it, I would still keep it, as it's sucha uncommon and nice piece of engineering and build quality.

Nice to hear the MASH DAC is good... didn't even that "MASH" referred to a DAC !  :-/O
The SL-PJ25 makes no mention of it on the front panel. However I have a couple other Technics players, a SL-PG200A and SL-P277A. Front panel look 90% similar. Both of them feature a huge "MASH3 markng on the tray face plate. Now I know what it refers to !  ;D
I first go the SL-P227A, which is a very sorry state. Very dirty outside, some rust on the chassis bottom plate, and a couple plastic bits broken from the transport... the clamping mechanism was dislodged and moving freely inside the cabinet... put it back together as best I could, and somehow it still reads CD's !  :)  I kept it only because I noticed it had a swing arm, which surprised me. Also, a nice detail... it is the only player in my entire "collection" where the headphone output can actually play loud ! In all my other player, whether they feature a volume control or not, it won't play loud. I use the headphone output to fix all these players, as I have only one CD input on my amplifier, already used for my main player, the one I use to listen to music at the bench... don't know if one can connect another CD player (the device under test I mean) to the other inputs of the amp : Phono, Tuner, Tape1, Tape2... haven't checked the manual for the amp, but I guess each input expect a different signal amplitude and might apply some analog "processing" different on, each type of input. I don't know, maybe some filtering/bandwidth limiting tailored to each type of device... something like that...

Anyway, I intended to "restore" that player, treat the rust, give it a good clean, try to super glue the broken plastic bits back onto the transport... try to at least. Now that you are telling me that this MASH DAC is worthy, that's another reason for me to keep it...

The second player, 99% similar, also a swing arm, sold for part. What the seller did not say, is that the player clearly got dropped from the top of the Eiffel tower !   :scared:  Wow... for parts it is indeed ! Though I could use it to help me fix the first player. Somehow, despite massive mechanical damage, it still powers up and the disc spins.. but it won't read it.



Toshiba : tried a Philips remote, indeed it works, hjust tried ! Good to know...
Luckily the player came with its original Toshiba remote control. First time I see a remote where you can select the "index". Don't even know what that means ! Maybe an audio track can be further divided in sub-tracks, and the "index" lets you navigate from one sub-track to the next.... don't know. Never had a music CD that had indexes ?! Maybe it could be useful for something like an audio book or something ? Lots of content so a track could represent a chapter, and you could further divide a chapter in sub-sections... dunno.

Anyway, "great" news : while trying the remote control(s) on the Toshiba, I eventually witnessed the player misbehaving !  YES, there is something that needs fixing in this player after all !  :box:

Symptoms :

- while the CD was playing, I could hear a weird noise coming from the cabinet, louder that I found acceptable. Thought oh no, the spindle motor is on its last leg, bad day ! But, I pulled the top cover and found that instead, the problem came from the DC motor that operates teh tray ! It was constantly running ! Tray was already closed, CD was being played, yet bloody motor was still trying to close the tray !  :scared:
I stopped the playback, open the tray, closed it... and the motor stopped as expected. Did not misbehave anymore, hmmm.....

- Later, in the middle of playing, suddenly playback stopped, and the VFD displayed the TOC, as it does following the insertion of a disc ! So I had to press the Play button to get it going again.

- Later again, as I was operating the tray a few times to test it, it opened only 80% of the way then instantly moved back and closed ! So didn't have time to insert a CD.

It's all random and weird.. however it all adds up, makes a consistent picture, I think, if we had a dodgy micro-switch, the one that detects that the tray is closed. So might have to replace it. Looks like a bog standard tactile switch though, nothing special, soldered directly to the motherboard. Same kind you find for all the buttons on a front panel.

Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Gyro on March 30, 2021, 05:29:39 pm
Just to ve clear... you mean, the "map" of track numbers that I see on some players ? A "grid " populated with track numbers ? There is a special chip, H/W required to implement this functionality, the main CPU can't be bothered ?
Looking at the pic I took of the main board of the Toshiba, I see only one unpopulated chip, a big 24pin DIP chip, at the very bottom right corner of the board, right by the right side of the DAC.. is that it ?

Yes, that's right. The non-fitted 24pin chip is an EEPROM - I never used the function but it presumably remembered the favourite tracks for a number of discs. The 'map' of track numbers takes up a lot of display segments, so the display driver probably has to sacrifice these in order to display simultaneous track and time.
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 30, 2021, 05:52:42 pm
I would check that ribbon cable carefully.  I used to see a lot of them fail in Sony changers of that vintage.  It flexes every time the tray is opened or closed, so they can develop open conductors.  Check it for continuity since any breaks can be practically invisible.

You mean the long and wide green flat flex that goes from the front panel to the transport ?

It does not flex at all, never moves. It's connected to the "BD" board under the transport.

Well, it tilts a quarter inch up and down when the transport tilts upwards to clamp the CD, it's a ridicule amount of flex given how long the cable is, no ? you mean such a tiny movement is enough to break traces in the cable ?!  :-\

Anyway, not taking any chances, so I checked continuity methodically between both ends of the cable... I get a sold connection on all 22 conductors.

Pulled the front panel to get better access. Now I have it apart, will be easy to do the next step : probe all power rails on that board to see how they are doing, especially ripple wise, in case we have a tired decoupling cap somewhere....

The symptoms though really point toward a failed driver IC. Its output stages must be shorted to full blast mode or something...

Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 30, 2021, 06:07:50 pm
Yes, that's right. The non-fitted 24pin chip is an EEPROM - I never used the function but it presumably remembered the favourite tracks for a number of discs.

Ah OK ! It looks more sophisticated than I first assumed, my bad  !  :-//
So looks like an audio CD can be identified uniquely, there is some ID string or checksum or UUID or something, stored in the TOC, so that the player can identify the disc when it is inserted. EEPROM so that it can remember the list of favorite tracks for the various discs, even if you power it off....hmmm, sounds like a neat feature, like it ! 8)
I guess it needed an external EEPROM since the MCU's 30 years ago didn't have a built-in EEPROM, or at least it was nowhere near widespread/common as it is today...

I have a Philips CD824 (picture below, the one at the very bottom), with an "FTS" feature, think it stands for "Favortite Track System" or something... sounds like a similar feature as what you describe. Would be fun to read the contents of itrs EEPROM (if it's old enough to have an external one, not sure....), to read the discs ID, look it up in some disc database and find out what discs / music the previous owners listened to !  :-DD
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Gyro on March 30, 2021, 06:20:53 pm
Yes, there's all sorts of information buried in the subcode data - including CD Text (Album Title, Artist, track names etc), that few players support. I have a Kenwood one that does and has a scrolling dot matrix ascii display - it's a bit like DAB radio text displays.
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: shakalnokturn on March 30, 2021, 07:01:29 pm
Awww! Seeing those player stacked up reminds me of my collection still in cardboard boxes since the move.
What ever garage you're trying to build be sure it's going to be too small it's going to be hard to stop now...  :-/O ;)
You're right about the drawer position switches they're are a common problem.
You can use any line level input on your amplifier. (Not Phono or Microphone.)
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 30, 2021, 08:29:29 pm
Drawings for the garage attached below ! 

House is 60m2 , garage will be... 60m2 too !

Would make it 150m2 if I could, but yard is too small and so is my salary.. gotta pay property taxes on garages too !  :palm:

I already know it's gonna be too small, because 20% of it will be to make a cellar, a third / central part for a second/week-end car, and the last third+ needs to accommodate my stock of wood and woodworking bench and power tools to go with it... then I need lots of space to store the tons of tools and equipment that my soon to be 76 year old dad will be donating to me. If by some miracle there remains a little space for some shelves... yes, I will be using that to store electronic stuff.... but I already have my collection of old tube Tektronix scopes so... not much space will be left for Cd players or anything else, I anticipate !

Line level ? Sounds like standardized signal amplitude ? That would be cool indeed ! I noticed that every CD players I have always specifies : "line out, 2V output". RMS I guess ?  Peak ? Peak to Peak ?  So "line" level is 2Volts then.. ;good to know.

So I can wire my devices under test on the Tape or Tuner inputs then, cool... that will make working on stuff much easier indeed.

Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: tautech on March 30, 2021, 08:37:35 pm
 :o  :o  :o
 :clap:
You need to introduce yourself with that pic in the TEA thread Vince.

Now we know why those old Teks are in short supply in the EU !  :-DD
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: shakalnokturn on March 30, 2021, 10:48:06 pm
A slight case of boat anchory...
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: tautech on March 30, 2021, 10:50:41 pm
A slight case of boat anchory...
Someone has to save them from the tube pilferers !
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Gyro on March 31, 2021, 09:58:19 am
Someone has to save them from the tube pilferers !

Same with the Philips CD players. TDA1541As go for stupid sums on ebay! Most of them are re-marked fakes from China, either complete fakes that simply cook or 'uprated' by adding single crown or double crown markings.

The only way to guarantee a genuine part these days is to pilfer one from an old player.
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 31, 2021, 02:45:57 pm
:o  :o  :o
 :clap:
You need to introduce yourself with that pic in the TEA thread Vince.

I am not sure I qualify for the TE club ?! ... will say hi anyway, bandwidth being cheap these days.

Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on March 31, 2021, 02:55:32 pm
Someone has to save them from the tube pilferers ! 

Exactly ! Though not my primary intention at all, it's none the less a valuable side effect...

Seeing people harvesting the tubes from these scopes and then dumping the scopes, leaves me speechless. They don't deserve to live...

However, in my somewhat sizeable experience buying these things, I have to be honest the pilferers are a minority. Think I came across maybe 3 of them, really blatant ones. Most other people just want to flog these old things they got in house clearing or in an auction as part of a lot, but don't know squat about the tube "market", they are just the random Joe who wants to ma ke a buck or two from this anchor, rather than dumping it. Then at the other end of the spectrum you  scope that belonged to the old man that just died, son want the scope to go to a good home and is asking fair money. I even have a few who asked me to give them news of the upcoming restoration !
You get the whole spectrum of people, just like on any subject... human kind is diverse...
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Gyro on April 01, 2021, 09:51:05 am
Just reading back through the thread, I noticed I missed a couple of questions ...

Toshiba : tried a Philips remote, indeed it works, hjust tried ! Good to know...
Luckily the player came with its original Toshiba remote control. First time I see a remote where you can select the "index". Don't even know what that means ! Maybe an audio track can be further divided in sub-tracks, and the "index" lets you navigate from one sub-track to the next.... don't know. Never had a music CD that had indexes ?! Maybe it could be useful for something like an audio book or something ? Lots of content so a track could represent a chapter, and you could further divide a chapter in sub-sections... dunno.

Yes, 'Index' is a sub-division of a track, it's defined in the CD 'Red book' spec but hardly ever used. The only CDs I found it used on is the double disk set of Andrew Lloyd Webber's Phantom of the Opera. Each disc is completely Track 1, but with incrementing Index!  You get things like this on the earlier players which were adhering closely to the spec, but on later players, manufacturers no longer bothered supporting them. The same with 'de-emphasis' - similar to RIAA equalisation or vinyl - it was used on some early CDs to improve SNR or high frequency quality (probably mainly on the first 14 bit DACs). If you look at the schematic of the analogue stage after the TDA1541, you can see a couple of JFETs which are used to switch frequency response modifying components. Later players implemented it in the digital filters incorporated in their delta-sigma DACs or stopped supporting it entirely.

Quote
Anyway, "great" news : while trying the remote control(s) on the Toshiba, I eventually witnessed the player misbehaving !  YES, there is something that needs fixing in this player after all !  :box:

Symptoms :

- while the CD was playing, I could hear a weird noise coming from the cabinet, louder that I found acceptable. Thought oh no, the spindle motor is on its last leg, bad day ! But, I pulled the top cover and found that instead, the problem came from the DC motor that operates teh tray ! It was constantly running ! Tray was already closed, CD was being played, yet bloody motor was still trying to close the tray !  :scared:
I stopped the playback, open the tray, closed it... and the motor stopped as expected. Did not misbehave anymore, hmmm.....

- Later, in the middle of playing, suddenly playback stopped, and the VFD displayed the TOC, as it does following the insertion of a disc ! So I had to press the Play button to get it going again.

- Later again, as I was operating the tray a few times to test it, it opened only 80% of the way then instantly moved back and closed ! So didn't have time to insert a CD.

It's all random and weird.. however it all adds up, makes a consistent picture, I think, if we had a dodgy micro-switch, the one that detects that the tray is closed. So might have to replace it. Looks like a bog standard tactile switch though, nothing special, soldered directly to the motherboard. Same kind you find for all the buttons on a front panel.

Yes, that is almost certainly that tactile switch on the PCB gone intermittent. It is the only limit switch on the whole transport and detects when the drawer is fully open or fully closed. A little contact cleaner dripped in might cure it, but replacement is easy. It won't be an alignment issue because the mechanics have a spring mechanism with good travel.
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on April 01, 2021, 09:08:34 pm
Thanks for the info Gyro, I will go to bed in 30 seconds, feeling a bit smarter indeed...

Will go and replace that micro-switch on the Toshiba. Will salvage a switch maybe on that Technics players that fell from the Eiffel tower. If I take one from the almost never used buttons, they should have next to zero wear on them.
Not sure how contact cleaner would manage to seep into that style of switch though ? Looks kinda sealed...
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: shakalnokturn on April 01, 2021, 09:24:27 pm
May I call that a mistake...?

Wear is one thing, not what seems to cause those switches to fail most of the time. If anything it's black layer of oxide (I don't know the chemistry at play here) that causes them to have poor contacts so seldom used switches are actually more prone to this because there's no mechanical action to "clean" them

They're not sealed and a spraying and very thourough clicking can work wonders.
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on April 01, 2021, 09:54:15 pm
Ah...OK.

I said that because every time I had a micro switch like these fail, in whatever piece of equipment, it was always the one that got the most use, that started failing, getting intermittent. Happened on my alarm clock, washing machine... and even my CDC486 Philips : I recently noticed the PLAY button is getting intermittent too now !

OK, will try some contact cleaner first...
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: shakalnokturn on April 01, 2021, 10:04:07 pm
Maybe wear then  ;D
I could be wrong...
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on April 04, 2021, 10:24:08 am
Probably too much trouble and also assumes that the other driver outputs are ok. Pins 10 and 11 should give you the answer anyway.


OK, let's get back on track.... this thread is about a Sony CDP-291 isn't it ? Sorry for the digressions.

So, I worked a bit on it.. took only a few minutes to declare it a write off.  This is the end of this repair...

Pulled the transport out of the loading mechanism, so I can get better access the PCB and things in general...

Checked power supplies, after having first removed one of the gears that drive the pickup, so the sledge motor can still turn yet the pickup is not self destructing anymore, banging/bouncing constantly against its stop.

- There is +5V for the digital decoder chip. That rail is spot on and next to zero ripple, perfect.

- Then there is +7V for the driver IC/motors, or so the schematic says on the connector pinout. But on the power board PCB it's marked as 8V. On the schematic, the test point on the driver IC reads 8.2V... and as for me, I measured 8.6V !  Quite a bit of ripple, 35mV (using non RMS DMM) of ripple, but given that the sledge motor was running, seems fine to me.


As Gyro suggested, I then checked the differential inputs corresponding to the sledge motor, pins 10 and 11. Given that the motor is turning full blast, I should therefore be able to measure a significant differential voltage between those two input pins. I didn't care about the ground referenced voltage on those individual pins, irrelevant, only the diff Voltage is relevant.  I measured.... a dead ZERO !

So yes, that driver IC is indeed faulty, powering the sledge motor full blast even though it's not being asked to do so.

But there is more !!!

I was playing around with the little flat flex cable that connects the pickup to the control board.... glad I did, was worth a look :

- On the control board side of the cable, looks weird : the contacts were clearly visible as if the cable had not been fully pushed in. Contacts look like there is come corrosion, and the contacts toward the center of the cable, look kinda damaged, half lifted from the plastic backing. I don't know, It just all looks very messy...

- On the other side of the cable, where it plugs to the pickup, that's even more entertaining : the cable this time looked fully inserted, no metal visible that I could see.... pulled the cable anyway and.... WHAT ?!  There is NO metal/contacts to be seen ! See pictures ! At first I thought wow, weird, maybe the cable broke and the contacts are still inside the connector or something... but no. There are no bits and pieces left stuck inside the connector, and when you look closely at the cable, you can clearly see that it was intentionally CUT by hand !  Edge was cut clean, it's not broken due to fatigue/stress. The edge is also not straight nor square. The contacts at the end of this cable have clearly been deliberately cut by someone !!   :scared:


So... end of repair. Driver IS is 20 euros shipped, a new cable for that pick-up is 10 euros or so IIRC (though I could maybe put the old one back into shape if I was desperate).... not worth the money nor my time... will keep it for parts.
Think I need to organize my pile of players a bit better. I should have several stacks :

- One for the players that wored out of the box, or that I have successfully repaired
- Another stack for fulty ones with an electrical failure
- Another stak for faulty ones with a mechanical failutre, waiting for a gear to be modeled and 3D printed.
- Another stack for worthless, hopeless POS , for parts only.


Will pull on of the micro switches from its front panel so I can fix the Toshiba....

Now going to report to the seller, he was so eager to kjnow the outcome ! I doubt he was the one who cut that flat flex, or else why would he ask me for news of the repair... unless he is some kind of weirdo, a psychopath of some sort ?! Hmmm....
Maybe his girlfriend tried to get it repaired without telling him, to offer that as a birthday present or something. Repair failed so she just kept silent....

Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Gyro on April 04, 2021, 10:57:39 am
Yuk, messy.

That ribbon is single sided traces (the contacts just wrap around both sides), but the last photo looks like either a previous repair or extreme tin whisker growth (I think the latter). It would be worth clearing the shorts between the traces and trying it again.
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on April 04, 2021, 11:35:57 am
It would be worth clearing the shorts between the traces and trying it again.

Uh ? As I said the other end of the cable has been cut... and the driver IC is kapput.

How will inserting just one end of the cable fix that ?!   :-//
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Gyro on April 04, 2021, 11:45:16 am
Ah ok, I didn't understand that the images were different ends of the same cable, I thought they were opposite sides of the same end.

If you have confirmed the dead driver IC then there's nothing more to be done, economically.
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on April 04, 2021, 03:52:49 pm
Yep, that's the end for him !

That's good... now I can clear the bench and move on to more interesting players like that Radiola / CD371  for example !  8)
Let's fix that one.... new thread coming up !  ;D
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on April 04, 2021, 08:53:38 pm
Seller got back to me. It becomes clearer now.... it was not his personal CD players, so he never used  and doesn't know anything about its history. Said he hates to to see old gear being dumped, so every now and then he buys a palette load, a big lot of old hifi gear, and tries to save them. He gives them a quick ride, sells those that can still work, and sells the defective ones for parts, lie the one I bought from him. So basically he just power it up, heard that horrible noise and that's about it. He knows squat about electronics so he didn't investigate anything, just listed for parts and that's it.

So, he is innocent, he didn't mess with the players, neither did his G/F ! LOL  Just bad luck.

Said he was interested in what the problem was as he would like to learn how to fix more of this stuff... but he doesn't even know the slightest thing about electrical or electronic stuff, so sadly the learning curve would not be economically viable for him !  :-[

Anyway, on to the next CD player...
Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on May 09, 2021, 03:05:26 pm
OK, a month and 4 days later, I am revisiting this POS of a CD player... to give it a second chance.

Nothing this player did to convince me to change my mind about him, but rather a general movement recently where I decied to try harder to get my pile of unrepairable CD players.. repaired after all. Most of my players do'nt work, for one reason or another, kills me. I am trying to sell as many of them as possible to recoup some of the 300 Euros I poured into them, and I can only do that if I can fix as many of them as possible. It's ahrd enough to sell a working old players, so a parts unit is not even worth trying to sell, not worth the bother.

So I am trying hard to see how I could maybe rescue some of them which in my first pass I deemed hopeless.

Have already repaired the Philips CD824 which had a broken gear, because you can actually surprinsgly buy replacement gears these days, for a reasonable amount of money. That player will soon be for sale then.

As for the Sony CDP-291 discussed in this topic... I just had another look for this servo/motor driver IC that's kaput. somehow someone on Ebay is selliing his one much cheaper than the others, only 6,55 Euros shipped... at that price it's worth giving it a shot. Might be a dead chip of course, might be an alarm clock or egg timer chip in disguise (but so are all the other ones for sale...), you never know. But for 6,55 Euros I am willing to give a try, as it's the only hope this player has of resurrecting.

As for the damaged/vandalized pickup flat flex, it might be repairable, will give it a try. If that fails, I could try using another flat flex. It looks like a standard cable and I have salvage a few of these here and there. Of course I won't have the exact one I need, but if I find one that's too long, I think it might still work OK. As for width, looking how they are made, it seems it would be pretty straight forward to take a wider cable and slice it along with a sharp blade to make it the correct width/number of conductors. The appropriate cable Is available brand new, but way too expensive (10+ bucks IIRC) to make the repair economically viable, so it's not an option.

Anyway, will probably take a month or two for that chip to arrive from china, as always, so don't hold your breath.... 

Title: Re: Vintage CD player repair : Sony CDP-291 with transport issues...
Post by: Vince on May 26, 2021, 04:01:39 pm
Back for the final episode. Took "only" 2 weeks to get the replacement motor/servo driver chip from China.

Looks brand new, and still sealed in what looks like a cut reel for a pick and place machine. Inspired confidence. Confidence was high.

Then also had to do something about the mutilated pickup flat flex.   Luckily I had one in stock that was the same pitch, almost the same length but not shorter, rather a little longer, so great. Was wider/more conductors, so I trimmed it to the proper width with a sharp blade, was easy enough. So that bit at least did not cost me anything. I knwe slavaging all these flat flex cables was not a pure waste of time and space, see ! !!  :-DD

So, put the "new" cable in place, soldered the nex chip on the BD board.... no joy.

At leas tnow the pickup stopped banging and bouncing on its stop, so that's good . However it won't move AT ALL now ! When you insert a disc it does not move, when you power up the player normally it should move to the center of the disc, it does not.
Spindle does not spin. Tray opens up when you press the button on the front panel, however when you press it again, this time to close it... it won't react at all, dead as a dodo. However it CAN close.... if you power the player up while the tray is open, it will automatically close it. So it can close it.... when IT wants to, not when III ask it to !

Wasted enough time an money on this thing. Maybe the chip is counterfeit, or defective, I don't care.... I am done with this POS. It's so cheaply built even if I could sell it it would not pay me for the chip I bough and the time I spent on it... so it's time to be reasonable and call it quits.

I have not put it back together hastily, and stacked it on top of my "for parts" pile. A growing pile...

You can't fix them all...